Posted By Hugh Hoagland,
Monday, September 16, 2013
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The 90-year-old technology of using rubber
gloves for shock and leather gloves for protection of the rubber soon
could be turned on its head by innovation.
For years, we have
heard the question, "What about gloves in arc flash?” The reason this question
wasn’t answered sooner is complicated, but the standard is now available. ASTM
F2675-13, Test Method For Determining Arc Ratings of Hand Protective
Products Developed and Used for Electrical Arc Flash Protection, is an ASTM
International standard with an approval date of June 1, 2013, that was expected
to be published by ASTM International within the month of July. Testing is
progressing already, with more than 25 types of gloves tested in the past few
years, now having a specific standard to target.
Gloves meeting this standard may not be designed for
shock. Only ASTM D120-compliant gloves are currently approved for use for
protection from shock, but some ASTM D120 gloves, all of which are made of
rubber, have been tested by this method and could begin to be labeled as such
in the near future for the information of the end user. The method, however,
really was designed for protection from arc flash only, thus the title.
ASTM D120 gloves
on the market today are made only of
rubber and are primarily for shock protection, though historically, they have
been covered with an ASTM F696 leather protector glove and provide excellent
arc-flash protection. The rubber gloves, however, can ignite in arc flash, so a
small contingent of the ASTM F18 committee wanted them excluded from the required
testing to avoid a possible legal requirement that could not be met. However,
rubber gloves that have been tested have shown a strong performance in this arc
test method, and certain additives could make them even more flame-resistant in
the future. Research is ongoing, but some suppliers plan to label their D120
gloves with F2675 arc ratings and ignition values. Check to see if your
supplier has data. Different colors will have different results; and the results,
to date, have varied between suppliers even with the same colors because the
colors are formulated with different additives to achieve the color.
Photo 2. Rubber gloves with leather protectors are quite protective from arc flashes. New technologies might make them more flexible and offer a better grip.
Photo 3. A new leather protector has patented "grip strips” developed by a Canadian lineman. It also has a 40 cal/cm² arc rating
Advantages for End Users and Manufacturers
So if this standard is for arc-flash gloves
that might not meet ASTM D120 for shock, what good are they? The gloves are
useful for arc flash as work gloves. If your hazard assessment for an
electrical task includes a shock hazard, ASTM D120 gloves are still your only
option, with or without a leather protector (see OSHA, NFPA 70E, and ASTM F496
requirements for protector gloves).
Uses for arc flash gloves include the following:
1. "Heavy duty leather gloves” for arc-flash
protection (NFPA 70E-2012, Standard for Electrical Safety in the Workplace,
required these for several jobs without shock hazards). But because there was
no arc flash test method for gloves, the committee had to make the gloves of a
certain thickness. Now, the gloves could be made thinner and still meet minimum
protection for the hazard.
2. To replace "heavy duty leather work gloves” when
they are inadequate for other multiple threats. Non-leather gloves are being
worn in more workplaces today. Non-leather specialty gloves that grip when wet
or oily can be engineered to make the gloves more task-specific and
ergonomically designed. Now, these gloves also can be arc-rated so that a
machine operator who is operating a disconnect will have no need to change
gloves when the tables are used for arc-flash hazard assessment but needs a
3. The NFPA 70E Table 130.7(C)(15)(a) Hazard/Risk
Category Classifications and Use of Rubber Insulating Gloves and Insulated and
Insulating Hand Tools-Alternating Current Equipment and 130.7(C)(15)(b) for
DC Equipment require "arc-rated gloves” or D120 gloves with F696 leather
protectors for certain tasks. Now, there will be "arc-rated gloves” for the
non-shock hazard tasks that have arc flash potential.
4. The additional option the ASTM F18 committee is
working on now is to allow OSHA-required (1910.137) "protector gloves” to be
something other than leather. The 90-year-old technology of using rubber gloves
for shock and leather gloves for protection of the rubber soon could be turned
on its head by innovation because the cut standards, puncture standards, and
now arc-flash standards for gloves are in place to specify new options to
protect workers from shock and arc flash while making gloves lighter, thinner,
and giving a better grip.
A new glove on the market from Canada is an ASTM F696
leather glove with a patented added polymer strip on part of the palm, making
the leather protector glove have improved grip when oily or wet. This was
developed by a lineman in Canada and tested for arc flash last year. It is a
potential game changer for protectors. Watch for other innovative designs in
protectors soon, now that a performance based test method is available.
mentions "protector gloves” in the standards but doesn’t call them "leather”
(though F696 is listed in the standard as acceptable), it is possible we could
see knit "protector gloves” being adopted for low voltage within the year. What
other options could we see with test methods to test for real product
performance? Could we have other improvements in safety equipment for arc flash?
Testing has been driving innovation for several years, so expect change for the
Photo 4: Traditional leather protectors provide puncture, cut and arc flash protection but with this new standard the bar may be raised to allow materials other than leather to be protector gloves with better cut, puncture and even better arc protection in a thinner package. The possibility is now there.
Caution: When selecting gloves for arc flash
exposures, two considerations must be followed:
1. Assess the hazard for shock first. If shock
hazards exist, use an ASTM D120 rubber insulating glove under the arc flash
protector glove and properly match the length of the rubber to be the proper
length for the protector gloves. Most companies choose ASTM D696 leather
protectors. Additionally, the protector must be shorter than the rubber glove
by a distance set in ASTM F496.
2. Assess the arc flash hazard from a realistic
distance from the hazard. Most arc flash calculations are for a working
distance of 18–36 inches. The hands may well be closer, and this should be
considered in the hazard assessment.
Could arc flash crossover, multi-threat gloves for cut, chemical, and arc
flash protection be something to consider to update your safety program? Stay
tuned as these glove choices increase in the near future.
Hugh Hoagland is senior managing partner of
e-Hazard.com, a leading provider of arc flash and electrical safety training,
and senior consultant at ArcWear.com, the leading testing company for arc rated
materials and PPE.
Hand Protection -- Occupational Health & Safety,
http://ohsonline.com/articles/list/ht-hand-protection.aspx (accessed August 21,
This article was
published in the August 2013 issue of Occupational Health & Safety magazine.
©1105 Media Inc. Reprinted by permission from 1105 Media.
Posted By Steve Foran,
Monday, September 16, 2013
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Over the last few weeks I have been on the receiving end of unprecedented levels of customer service — at both extremes of the spectrum. The four quick incidents that follow all happened during a weekend away with some old friends.
First, being asked what we wanted for dinner in a restaurant as the waitress was swallowing food herself, and then she was eating pie at the register as we paid our bills. Second, at another meal one of my mates was patted on the back and told, "Finish it off,” instead of asked, "How is your meal?” The fact that he ate less than half of what was on his plate should have been a signal.
On a positive note, for the third incident we had a corner store owner almost do back flips to serve up a bag of ice and two ice cream cones. She was pleasant, talkative, and interested in us. She made us want to come back. And to wrap it up, when we asked the concierge at the resort to point us to our cabins, she explained very politely why she does not point and gestured using four fingers and an open hand. We felt like we learned a universal truth.
In each of these cases, what would prompt someone to act that way?
There are many reasons we could presuppose, all of which are superficial. For the mediocre servers, maybe their boss does not care, or they do not understand the importance of their job, or they do not have the proper training. I do not know.
As for the great servers, perhaps we caught them on a good day, or they are jazzed up about helping others, or they have an incentive to provide great service. Again, I am not sure why.
Regardless, there is one underlying reason that explains the difference between excellent service and mediocre service. The root cause rests in how the server thinks about his or her work.
For people who provide excellent service, they care. They care about the work they do and the customers they serve. For the people who provide mediocre service, quite simply they do not care.
Who knows why these individuals cared or not, but fortunately there is a cure for not caring. There is a feeling, that when elicited, is guaranteed to help people care more. It is the missing link to caring, as well as to excellent service and happy people. It is simple and it will transform someone who does not care into someone who cares.
The missing link is gratitude and you can help someone experience it by asking the question, "What are you grateful for about your work?”
Be patient and listen. Resist the temptation to tell them what they should be grateful for. If they continue having difficulty in finding something to be grateful for, then share what you are grateful for. Be open and honest. Then ask them the question again.
Once someone is genuinely grateful, they cannot help but care. They will seek out solutions to the superficial reasons like lack of training. As a result, they will be happier and the customers they serve will be happier too. Remember, this is not a "bucket list” question. It is a question that must be asked over and over again so that caring and excellent service do not become flavors of the month.
There is one caveat. If you want this technique to work with others, first you must be genuinely grateful and you must care. So make sure you have a good sense of what you are grateful for concerning what you do and those you serve. If someone senses that you are not genuine in how you express your gratitude or your care, the question just might backfire on you.
Read more by Steve Foran
Posted By Jeff Greef,
Monday, September 16, 2013
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Most residential electrical services are not
designed to accept two sources of power, but they are often utilized for the purpose
of connecting PV systems in addition to utility power. NEC Article 705
provides accommodation for such connections, but sometimes these accommodations
cannot be used without replacing the service enclosure, or adding a distribution
panel, or making a supply-side connection, all of which entail additional cost.
Occasionally installers get "creative” by tapping directly into feeder
conductors coming off the service to a subpanel in the house. Article 705 is
silent on this specific method, and controversy exists as to whether it is a
compliant method at all. Jurisdictions must decide for themselves whether this
is compliant; and if they do allow it, examiners and inspectors must be aware
of how such an installation triggers the provisions of Article 705 which are
meant to prevent the overloading of conductors or busbars. This article
explores the specific issues encountered in such an installation.
For a broader treatment of NEC 705.12(D)
regarding requirements for making load-side connections for PV systems, see the
papers and articles on the subject written by John Wiles of the Institute for
Energy and the Environment at New Mexico State University. Those articles are
referred to at the end of this one. Mr. Wiles has written extensively on the
fundamental intent of 705.12(D). The focus of this article is how 705.12(D) comes
into play only in the case of a load-side tap. This specific issue brings the
fundamental intent of this code section to bear and so requires a brush up on
the basics of these provisions. See John Wiles’ article in the January-February
issue of IAEI magazine, "Unraveling the Mysterious 705.12(D) Load Side
PV Connections,” which demonstrates the basic intent of these provisions as
they pertain to connections at a load center bus bar with a breaker. Mr. Wiles’
article does not address the issue of tapping into feeders; however, the same
principles that come into play at bus bars with breakers also apply with
feeders and taps.
When a PV system is connected to a load center by a
breaker, the problem that can occur is overloading the busbars (see figure 1).
For example, if the main disconnect and
busbars are rated at 200 amps, and the PV system is capable of producing 40
amps, it is then possible to pull 240 amps off the busbars via feeders and
branch circuits, if the users of the system connect enough equipment simultaneously. Section 705.12(D)(2) requires that the "sum
of the ampere ratings of overcurrent devices in circuits supplying power to a
busbar or conductor shall not exceed 120 percent of the rating of the busbar or
conductor.” So, 240 amps are allowed onto busbars rated at 200 amps. But,
705.12(D)(7) requires that PV breakers be located at the opposite end of the
busbar from the utility feed. Figure 1 shows why. If the PV 40-amp breaker is
located adjacent to the utility feed, the sum of amperage on the busbars
immediately after that breaker can be 240 amps, too high for the metal of the
busbar. But, if the breaker is located at the opposite end, this cannot occur,
since power is fed from two different directions. As we will see, a similar scenario can exist
when tapping into feeders with a PV system.
Figure 1. PV load side connection at breaker complaint and non-compliant breaker locations
Tapping into Feeders
Figure 2 shows conductors from a PV inverter
connected to the system by tapping into feeder conductors coming off a breaker
in the service panel. The figure shows a service that has very few breaker
slots, only enough for feeders to a subpanel and several others for loads such
as AC and range. On such a panel, if all slots are taken, the installer cannot
add a breaker to connect the PV. The connection could be made with a breaker at
the subpanel (if all rules are followed), but routing conduit to a subpanel
inside the house is often difficult. A line side connection could be made at
this service panel, but this entails installation of an additional service
disconnect and could violate the terms of listing of the meter enclosure, which
was designed to handle only utility power. A separate subpanel could be
installed adjacent to the service, but this is expensive. Tapping directly into
the feeders is easy, but is it safe and compliant?
Figure 2. Load side PV tap overloaded feeders and busbars
Is This a Tap?
NEC 240.2 defines a tap conductor as "…a
conductor, other than a service conductor, that has overcurrent protection
ahead of its point of supply that exceeds the value permitted for similar
conductors that are protected as described elsewhere in 240.4.” In figure 2,
the overcurrent protection for the feeders exceeds the value permitted for the
PV conductors spliced onto the feeders, but one could argue that those feeders
are not the point of supply for the PV conductors, so that these conductors are
not "taps” at all. However, in the event of fault current between the splice
and inverter, the feeders will supply fault current to the spliced PV
conductors, and the only overcurrent protection to clear this fault is the
feeder OCPD. For this reason the PV conductors qualify as tap conductors, even
though in normal operation they will put current onto the feeders rather than
pull current off of them. If such an installation is allowed by the AHJ, the
tap rules of 240.21(B) must be followed.
Can a Tap Connect PV?
Section 705.12(D)(1) states that the connection
from an inverter must be made "at a
dedicated circuit breaker or fusible disconnecting means.” Figure 2 shows the
tap conductors originating from a 60-amp fused disconnect. Is the connection of
the PV system to the other system made at the tap splice itself, or is it made
at the 60-amp disconnect? Opinions seem to vary on this point. Some consider
that the tap conductors from the splice to the disconnect are part of the other
system, so that the two systems are connected at the disconnect. Others
consider that the tap conductors are part of the PV system, so that the two
systems are connected at the splice. Taking the latter position, the connection
is not compliant because it is not made at a breaker or fusible disconnect, but
rather at a splice. Taking the former, it is compliant since the connection is
at a fused disconnect. Since the code is silent on this issue, each AHJ must
decide this point for himself. The remainder of this article presumes that the
tap connection is judged compliant if it leads to a breaker or fusible
disconnect as in figure 2.
Overloading the Feeders
Figure 2 shows the PV system spliced into the
feeder conductors somewhere along their length. The feeders are protected by a
100-amp breaker. Let us say for sake of discussion that the feeders themselves
and the busbars on the subpanel are rated at 100 amps each, and that the PV
system is capable of putting 30 amps onto the feeders in sunlight. When few or
no loads are being pulled off the subpanel during daylight, the current from
the PV system will backfeed toward the utility. When more than 30 amps are
pulled from the subpanel in daylight, the 30 amps from the PV will go to the
subpanel and the utility will make up the difference. If the building users
connect enough equipment during daylight, they can conceivably pull a total of
130 amps through the subpanel before the 100-amp feeder breaker trips or the
30-amp PV breaker trips.
Let’s say the
users are pulling 130 amps and no breaker trips. The section of the feeders
from the 100-amp feeder breaker to the splice is carrying 100 amps, its maximum
rating. The PV tap conductors from the 30-amp disconnect to the splice are
carrying 30 amps, for which they are rated. But the section of feeders from the
PV splice to the subpanel busbars is carrying 130 amps. As well, the tops of
the busbars themselves, before any breakers take loads off the busbars, are
carrying 130 amps. In this case, both the feeders from the splice and the busbars
are well beyond their ratings and can overheat, distort, burn insulation, etc.,
with no breaker tripping to protect the circuit.
If the PV system were smaller and its breakers were
at 20 amps, the feeders from the splice and the busbar tops would carry 120
amps, which is 120 percent of their rating, and therefore compliant with
705.12(D)(2), the 120 percent rule. However, this installation still violates
the intent, if not exactly the wording, of 705.12(D)(7) which requires that the
connection in a panelboard be made at the opposite end of the busbars from the primary power source. But in this case, we
are dealing with a connection at feeders as well as at a panelboard. Since the
provision regards only a connection at a panelboard, it is debatable whether it
applies to feeders. But still the intent of the provision is clear — the
connections must be made in a way that avoids overloading any given section of
busbar or conductor. In both the 30-amp and 20-amp PV scenarios described
above, such serious overloading is possible because the tap does not connect at
the opposite end from the primary feed. It is added to the primary feed, so
that the sum of amperages enters the feeders mid-way, and the panel from only
one end, in these cases overloading both feeders and busbars.
Size Down the Feeder Breaker
Let us say
that the installer suggests sizing down the breaker for the feeders from 100
amps to 70 amps (in the 30-amp PV scenario). In this case, it will no longer be
possible to pull more than 100 amps through any section of conductor or busbar.
However, this assumes that 30 amps are always available from the PV system
which, of course, they are not when sunlight is not on the PV array panels. At
night the maximum that can be pulled through the subpanel is the 70 amps. If
load calculations for the building show that 70 amps is enough, this is a quick
fix for an otherwise non-compliant situation. If load calculations are over 70
amps, there is a risk of nuisance tripping at the feeder breaker; but the absence
of a working calculation should prevent the installation at all.
Oversized Feeders and Busbars
consider the situation if both the feeders and the subpanel busbars are
oversized to begin with. In figure 3, the feeders are rated for 140 amps and
the subpanel busbars are rated at 200 amps, but the feeder breaker is 100 amps
and the calculated load is below 100 amps. Now the installer taps into the
feeders with 30 amps, and the users connect enough equipment to pull 130 amps
through the subpanel during daylight. Current in the feeders is below their
rating, and the panel is well below its capacity; but this still seems to
violate the provision in 705.12(D)(7) which tells us to locate the PV
connection at the opposite end. Or does it?
The text reads,
"Unless the panelboard is rated not less than the sum of the ampere ratings of
all overcurrent devices supplying it, a connection in a panelboard shall be
positioned at the opposite (load) end from the input feeder location… .” In
this case, the sum of the ampere ratings of the breakers is less than the
ratings of the subpanel busbars or the feeder conductors, so no possibility of
overload exists. This code provision is written to cover scenarios where
busbars are not oversized to begin with, where the addition of another power
source presents a possible overload problem. But the provision allows for
situations where equipment is oversized to begin with, which avoids the
possibility of overload so long as the total amperage fed into the busbars is
below the capacity of the equipment. The same principle applies to the feeder
conductors. Section 705.12(D)(7) is in place to prevent overheated equipment.
It is not necessary to locate the PV connection at the opposite end of the
busbars in this scenario because connecting it ahead or anywhere else cannot
cause an overload.
Figure 3. Load side PV tap oversized feeders and subpanel busbars
Tapped Feeders in a Gutter
shows an installation where three subpanels are fed off of tap conductors in a
gutter. Two possible locations are shown for tapping a PV system onto the main
feeders along with the taps for the subpanels. The same principles apply here
as in the above scenarios. If the PV system tie in occurs upstream of the taps
for the subpanels (PV tap location 1), the section of feeder between the PV tie
in and the first subpanel tap splice can theoretically have an amperage running
through it that is equal to the sum of the main disconnect breaker and the
amperage supplied by the PV system. If this total amperage is greater than 120
percent of the rating of the feeder, 705.12(D)(2) is violated. If it is within
120 percent, it is still necessary to locate the tap at the opposite (load) end
of the feeder, just as you would do with locating a breaker on a busbar, to
comply with 705.12(D)(7). PV tap location 2 shown in the figure is located
where its amperage cannot be added to the amperage coming from the main
disconnect on any given length of the feeder, avoiding overloading that
section. But if the main feeder is oversized to begin with, locating the PV tap
upstream of the subpanel taps is compliant so long as no section of conductor
(or busbar) is overloaded.
Figure 4. Load side PV tap in a gutter with feeder taps
Most residential service load centers are not
designed to accept secondary sources of power such as PV systems. Connecting to
these load centers can be easily done with a backfed circuit breaker, within
certain parameters. But installers are
faced with connecting to a wide range of load center configurations, where
sometimes such a breaker cannot be installed. Sometimes a load-side tap is the
option of choice. Such a connection raises various code issues which inspectors
and installers must be aware of. The basic principles of installation laid down
in the code for use in connecting with circuit breakers also apply when
installing a load-side tap. Thorough understanding of the principles behind the
provisions is essential to ensure safe, effective installations of PV
connections with load-side taps.
John Wiles articles at New Mexico State University
can be found at:
Solar Ready Residential Service Panel
The photo shows a Siemens "solar
ready” service panel which is produced as a response to the need for easier
connections with PV systems.
This panel design constitutes a
line-side tap. A separate set of busbars, rated at 60 amps, is supplied for
connecting to an inverter with a set of breakers. That set of busbars is
connected directly to the load side of the meter socket before the main
disconnect, bypassing the main busbars altogether. This also bypasses all the difficulties
involved with load-side connections.
Since the line-side tap
connection is integral with the equipment and a part of its listing, it avoids
the problem of violating the listing of a panel by connecting a line-side tap
where the equipment is not approved for such use. But it will be a long time
before significant numbers of such panels are installed; and, meanwhile, the
majority of PV installations will be done on older service panels that were not
designed for the use.
With effective application of
existing code provisions, those panels can be safely utilized with PV while we
make the decades-long transition to equipment designed for the purpose. But 20
years from now, you’ll still see someone trying to do a line-side tap into a
rusty Zinsco 100-amp service at the meter socket, because there is no room for
more breakers and the owners would rather spend their cash on granite
countertops than a nice shiny new service panel.
Jeff Greef is a combination inspector with the City
of Cupertino in Silicon Valley, California.
Posted By Joseph Wages, Jr.,
Monday, September 16, 2013
| Comments (0)
Fountains and reflection pools have been around for generations and make powerful statements and reminders of events that occurred at these locations. Beautifully built and constructed throughout the world, these locations are often works of art.
Photo 1. McKinney, Texas
On April 19, 1995, at 9:03 a.m., a tremendous explosion destroyed the Alfred P. Murrah Federal Building in Oklahoma City and 168 people lost their lives; but as a country, we lost much more. No longer could we take for granted that something like this could never happen again. As a people, we would always wonder when it would again. We looked at our children differently and gave them extra hugs. Things could never be the same again.
Photo 2. Oklahoma City Memorial
This happened in Middle America or what some consider Flyover country, and would leave its mark on the country as one of the worst domestic acts of terrorism to date. Many years later in 2001, the events known as "9/11” and the collapse of the Twin Towers would change this image and result in war.
Today, a reflection pool is part of the Oklahoma City Memorial, a solemn reminder of those events that allows the visitor to see his or her reflection as "someone changed by the events of that day.”
This destructive act took place roughly two hours from my home. Being a father, the loss of children weighed heavily on my heart. As a visitor to the site, I recall, my emotions were all over the place. I had gone as part of a group of men attending a Promise Keepers Rally held in the downtown area. It seemed that thousands stopped at the fountain to reflect on the events, to honor the victims, and to remember that which is important in life. On that day, for me, life took on new meaning in a personal way.
As you can imagine, the National Electrical Codehas requirements that govern electrical installations at these locations. Certain tragedies are, unfortunately, unavoidable due to the ill will of others. We can certainly do our best, however, to minimize or prevent senseless disasters from occurring by enacting strong Code adherence and educating as to its importance.
Photo 3. Fountain, Hot Springs, Arkansas. Millions of people have visited the waters found in Hot Springs National Park. Throughout Hot Springs there are numerous fountains and bath houses. Some people claim the waters from the fountains have therapeutic properties; and many of them use water bottles to "capture” this water for drinking purposes. But be careful at the fountains; you will find out quickly that the water is hot, and on a cold day, one can view the steam as it rises and quickly disappears.
Article 680 Swimming Pools, Fountains, and Similar Installations
I remember seeing my first fountain as a small child. This fountain was located inside the AQ Chicken House in Springdale, Arkansas. My mom would take us there when we would visit her brothers and sisters, and I would always ask for pennies to throw into the water. As I look back, this was an innocent time where wishes could be made with an expectation that they might happen. I can say that I never got any taller or got a chance at the NBA; but the fountain got a little richer from all those pennies from wish-making kids! This article deals with the construction and installation of electrical wiring at these locations.
Article 680 deals with these and other similar areas, such as the locations listed below:
- Swimming, wading, therapeutic and decorative pools
- Hot Tubs
- Hydromassage Bathtubs
We also need to keep in mind that the term body of water, used throughout Part I, applies only to bodies of water detailed in the scope, unless it has been otherwise amended. In this article we are going to look specifically at fountains and reflection pools. To do so, we need to start at the definitions.
Definitions are important to any project. The definitions we are interested in reside in 680.2. It is interesting to see that a reflection pool is located in the definition of a fountain.
Fountain. Fountains, ornamental pools, display pools, and reflection pools. The definition does not include drinking fountains.
Pool. Manufactured or field-constructed equipment designed to contain water on a permanent or semi-permanent basis and used for swimming, wading, immersion, or therapeutic purposes. (2011 NEC)
The term fountainapplies also to: ornamental pools, display pools, and reflection pools. Think about your Koi Pond tucked in the corner of your back yard. Have you ever considered it an ornamental pool? What about a display pool? What exactly is displayed at these pools? Reflection pools are familiar to many people; not only the reflection pool in Oklahoma City but also the reflection pool at the site of the former Twin Towers in New York City.
Interestingly enough, the code-making panelshad to take action on drinking fountains in the 1999 NEC. Language was placed into the definition specifically stating that drinking fountains were not included in the definition of fountains. It also made it clear that Article 680 did not apply to drinking fountains. This leads one to speculate that maybe an AHJ could have been trying to enforce the requirements found in Article 680 towards the drinking fountain.
Photo 4. Fountain luminaire with cord. Overheating protection of the electrical equipment is necessary for electrical equipment that depends on submersion for safe operation. A low-water cut-off or other approved means shall be provided when the equipment is no longer submerged.
Article 680 Part V, Fountains
Part five is where we zoom in on the specific requirements for fountains. The provisions of Part I and Part V of the article shall apply to all permanently installed fountains as defined in 680.2. As one might expect, luminaires, submersible pumps, and other submersible equipment shall be protected by a ground-fault circuit interrupter, unless listed for operation at low voltage contact limit or less and supplied by a transformer or power supply that complies with 680.23(A)(2).
So, what is meant by the low voltage contact limitas discussed above? This definition was new for the 2011 NEC. Let’s review this term.
Low Voltage Contact Limit
A voltage not exceeding the following values:
(1) 15 volts (RMS) for sinusoidal ac
(2) 21.2 volts peak for non-sinusoidal ac
(3) 30 volts for continuous dc
(4) 12.4 volts peak for dc that is interrupted at a rate of 10 to 200 Hz
[Excerpt from 2011 NEC,680.2]
"The low voltage contact limit described in this definition is based on the wet contact limits specified in Tables 11(A) and 11(B) in Chapter 9. In prior editions of the Code, the use of isolated winding type transformers that provided a sinusoidal ac voltage not exceeding 15 volts was used as the low voltage operational threshold for underwater luminaires. Although the 15-volt limit in Article 680 was based on a transformer-type power supply, it applied to all low- voltage systems. Any luminaire operating at more than 15 volts was required to be protected by a ground-fault circuit interrupter.
"In addition to sinusoidal alternating current, this definition also identifies the maximum acceptable safe levels for other voltage systems. Depending on the system, this maximum level is either higher or lower than that considered safe for sinusoidal ac voltage. New technologies for underwater lighting that integrate power supplies other than the traditional isolated winding type transformer have been developed, and this definition and associated requirements in Article 680 ensure that those new power supplies can be safely integrated into the swimming pool environment.” [Excerpt from 2011 NEC Handbook]
Photo 5. Sign in fountain, Fort Worth, Texas
Luminaires, Submersible Pumps and Other Submersible Equipment
The operating voltage for luminaires and submersible pumps and other submersible equipment is different. The operating voltage for supply circuits for luminaires shall not exceed 150 volts between conductors. The operating voltage for submersible pumps and other submersible equipment shall not exceed 300 volts or less between conductors.
Luminaires shall be installed in specific locations within these environments. Unless listed for above-water locations, the top of the lens shall be below the normal water level of the fountain. In the event that the lens is facing upward, it is to be adequately guarded to prevent contact by any person, or it is to be listed for use without a guard.
Nice to Know Info
Maximum Water Level. The highest level that water can reach before it spills out.
Note: Normal water level is different in each and every situation. As you might think, to define such a level would be impractical as each fountain or reflecting pool will be different. Therefore, it is recommended that you discuss the normal water level with the designer of the fountain before the project begins.
There is nothing that requires the installation of a luminaire in a pool of water; it is done by choice. Many luminaires are installed for aesthetic purposes to add to the enjoyment and tranquil feeling one might experience at the locations. Most generally, luminaires accentuate features found at that location.
The equipment located in fountains shall contain provisions for threaded conduit entries or shall be provided with a suitable flexible cord as required by 680.51(E). A maximum limit of 3.0 m (10 ft) has been mandated for the exposed cord within the fountain. Any cord located on the perimeter of the fountain shall be enclosed in an approved wiring method. An approved corrosive-resistant metal shall be used when metal parts are in contact with water. An example of a metal part that meets this requirement is brass.
Photo 6. Fountain in downtown Kansas City, Missouri
Equipment servicing is an important consideration when installing pool equipment. All equipment shall be removable from the fountain. This will allow for relamping of luminaires and for normal maintenance of equipment. Luminaires cannot be permanently embedded into the fountain structure so that water has to be removed or the fountain has to be drained in order to service the luminaires and equipment. All equipment that is to be part of a fountain shall be securely fastened in place or shall be inherently stable.
Nice to Know Info
What does "inherently stable” mean?
Inherent stability is often found throughout the aviation industry. It is the tendency of an aircraft to return to straight and level flight, when the controls are released by the pilot. Most aircraft are designed with this in mind and are said to be "inherently stable.” I guess that when applied to pool equipment, the equipment should return to its previous location and remain stable. Might there be an aviation guru involved with the NFPA process that got this term used here as well?
Receptacle Outlets Adjacent to Fountains
Fountains contain water. Water and electricity typically do not play well together. When we consider receptacles near fountains, we must keep this in mind. Ground-fault protection of these devices is necessary to ensure the safety of the user of the fountain. Any receptacle located within 6.0 m (20 ft) of the edge of the fountain shall be provided with GFCI-protection. This information can be found at 680.58.
Always remember to review the requirements for placement of equipment and other items associated with fountains. Code language dictates that the measurement for this equipment shall be made from inside the pool wall. Other code language from Article 680 for other situations will direct the installer to take the measurement from the outside of the pool wall. This requirment is located in 680.34. A slight oversight in reading and understanding these different requirements could be crucial to your receiving the final inspection results that make you happy.
Some fountains will be designed with signs in mind. Signs can take on many forms and fashions. The NEC deals with electric signs so not all signage will be affected by this language. Electric signs installed within a fountain or within 3.0 m (10 ft) of the fountain’s edge will be discussed next. Section 680.57(C) directs that "a fixed or stationary electric sign installed within a fountain shall be not less than 1.5 m (5 ft) inside the fountain measured from the outside edges of the fountain.”
In the event the sign is portable, we have two restrictions: (1) it shall not be placed within a pool or a fountain; and (2) it cannot be placed within 1.5 m (5 ft), measured horizontally, from the inside wall of a fountain.
A sign shall be grounded and bonded in accordance with 600.7. A disconnecting means conforming with both 600.6 and 680.12 shall be provided for a sign used with fountains.
Boxes and Enclosures
Boxes and enclosures are very important in a wet or damp location. These items will need to conform to 680.24 when used at a fountain. Each will need to be provided with threaded conduit entries or compressed glands and seals for cord entry. If the box or enclosure is to be submersible, it shall be constructed of copper, brass, or another approved corrosion-resistant material.
Section 680.52(B)(2)(a) requires a potting compound to prevent the entry of moisture for an underwater enclosure. The box or enclosure shall be firmly attached, per 680.52(B)(2)(b), to the fountain surface. If the box or enclosure is supported solely by conduits, the conduit shall be of copper, brass, stainless steel or another type of corrosion-resistant metal. Support shall be in accordance with 314.23(E) and (F).
Bonding and Grounding of Fountain
Do not take for granted the importance of grounding and bonding, which cannot be stressed enough in the installation process for the fountain. Bonding requirements are located at 680.53. The Informational Note further directs you to 250.122 for the sizing of these conductors that are attached from the metal piping systems to the equipment grounding conductor of the branch circuit.
Some equipment must be grounded. In 680.54, we find guidance that helps with this process. All electrical equipment — other than listed low-voltage luminaires not requiring grounding — located within the fountain or within 1.5 m (5 ft) of the inside wall of the fountain must be grounded. This also includes electrical equipment associated with the circulating system of the fountain, regardless of its proximity to the fountain.
Methods of grounding are discussed at 680.55(A). There are six code references that have applicable provisions for the fountain or reflection pool. In the event you have equipment supplied by a flexible cord, 680.55(B) needs to be consulted. All exposed non–current-carrying metal parts of electrical equipment that is supplied by a flexible cord shall be grounded by an insulated copper equipment grounding conductor that is an integral part of this cord. It shall be connected to an equipment grounding terminal located at the supply junction box, transformer enclosure, power supply enclosure, or other enclosure.
Cord- and Plug-Connected Equipment
We can’t escape cord- and plug-equipment. For guidance on installation practices, turn to 680.56(A) through (D). Maintenance of electrical equipment dictates that the power supply cords allow for this type of flexibility. Hence, all power supply cords shall be protected by ground-fault circuit interrupters.
There are also requirements that dictate the choice for cord types when used in fountains and reflection pools. If immersed in or exposed to water, a flexible cord shall be of the extra-hard usage type. This is typically designated in Table 400.4. The flexible cord shall also be a listed type with a "W” suffix.
A suitable potting compound is required for the end of the flexible cord jacket and for the flexible cord conductor that are intended to terminate within the equipment. This will prevent the entry of water into the equipment through the cord or its conductors. To prevent deteriorating effects from the water that may enter into the equipment, the ground connection shall be treated as well.
All flexible cord terminations shall be permanent, except for devices that need to be removed for maintenance, repair, or storage. This could include grounding-type attachment plugs and receptacles. Some of this equipment will be removed for storage and protection from the elements. Fountains are located at inside and outside locations throughout the world. In the event of freezing conditions, some of the equipment could be ruined. Removal of these items is essential to protect the equipment from these weather-related effects.
Photo 7. Spiritual Fountain, McKinney, Texas
I did not install the electrical equipment or inspect the fountain where I currently live. I am taking for granted that each person involved with this project has installed it as prescribed by the rules found within the National Electric Code. I think that if we all remembered how it could affect the end user, we would always have code-compliant projects. As stated earlier, water and electricity do not play well together. Enter a human life and things could go horribly wrong. It does not take a misguided individual blowing up a building to affect our daily lives; an unintentional mistake or oversight can have the same effects. Code requirements are important. Electrical installers are important. Electrical inspectors are important. Your loved ones are important to you! Who knows when they might visit or get into that pool!
Read more by Joseph Wages, Jr.
Posted By Steve Douglas,
Monday, September 16, 2013
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What are the criteria for connecting more than one motor on a single branch circuit overcurrent device?
To start to answer this question we need to re-visit the Canadian Electrical Code Part I (CE Code) definition of a branch circuit to recognize that a motor branch circuit is the circuit between the final overcurrent device and the motor including the conductor and the motor controller. In accordance with the CE Code the motor branch circuit conductors, controllers, and motors require short circuit protection in the form of an overcurrent device and motor requires overload protection.
Let’s start with the overload protection which is unique to a motor only.
The overload protection for the motor is designed to protect the motor in the event the motor is overloaded. The overload protection can be in the form of inherent overheating protection such as thermal protection (thermally protected or tp) or impedance protection (impedance protected or zp) as detailed in CSA Standard C22.2 No 77 Motors with Inherent Overheating Protection. A motor recognised as a motor with inherent overheating protection must be marked on the motor. (See photos 1 and 2).
Photo 1. A motor marked with inherent overheating protection
Photo 2. A motor that does not have inherent overheating protection
Other than the limited motors less than 1HP identified in CE Code Rule 28-308, motors not provided with inherent overheating protection will require remote overload protection. The setting of this overload protection is detailed in CE Code Rule 28-306. Motors with a service factor 1.15 and greater require the overload protection set at 125% of the motor full load ampacity and 115% for motors with a service factor less than 1.15. (See photo 3).
Photo 3. A motor nameplate where we can see the service factor (SF) of 1.15.
Remote overload protection can be provided by time delay fusing, overload relays, or other overload devices certified to CSA Standard C22.2 No 14 Industrial Control Equipment. (See photo 4).
Photo 4. Motor overload relay for a motor that does not have inherent overheating protection
With the overload dealt with, we can now focus on the short circuit protection requirements. The traditional method to provide short circuit protection is by the installation of overcurrent devices such as fuses or circuit breakers with an ampacity rating based on CE Code Table 29. As an example, the short circuit protection (overcurrent protection) required for a synchronous motor is limited to 175% of the motor full load ampacity for time delay fuses, 300% for non-time delay fuses and 250% for circuit breakers. Such limitations are intended to allow the motor to start without operating the overcurrent device during normal operation of the motor.
In the uncommon event these ratings of protection do not allow the motor to start because the motor inrush current is too high, CE Code Rule 28-200(d) allows the overcurrent protection to be further increased to 225% of the motor full load ampacity for time delay fuses, and (400% for motor up to 100 FLA and 300% for greater than 100 FLA) for circuit breakers.
Another method to provide short circuit protection is by using self-protected combination motor controllers also known as Type E or Type F combination motor controllers. CSA Standard C22.2 No 14 defines these controllers as:
A combination motor controller having non-replaceable or integral discriminating overload and short circuit current sensors, and provided with one or more sets of contacts where the contacts cannot be isolated for separate testing, shall be considered a Type E. (See photos 5A and 5B).
Photo 5A. Two Type E self-protected combination motor controllers. Photo 5B. The nameplate for one of the Type E self-protected combination motor controllers shown in Photo 5A. Note the accessories identified on the nameplate marking that must be installed before the controller can be accepted as a Type E self-protected combination motor controller.
A Type F combination motor controller is comprised of a magnetic or solid state motor controller coupled with a Type E controller. (See photos 6A and 6B)
Photo 6A. A Type F combination motor controller. Photo 6B. The nameplate for Type F combination motor controllers is shown in Photo 6A. Note the accessories identified on the nameplate marking that must be installed before the controller can be accepted as a Type F combination motor controller.
Type E and Type F self-protected combination motor controllers provide a disconnection means, short-circuit protective device, motor controller, and overload protection.
Another method to install multiple motors on a single branch circuit is with a controller marked suitable for motor group installation in conjunction with a main branch circuit overcurrent device (fuse of circuit breaker). (See photo 7).
Photo 7. A motor controller marked suitable for motor group installation
Precautions must be considered when grouping motors on a single branch circuit. The first precaution to consider is the markings on the controller for such group installations. CSA Standard C22.2 No 14 requires the maximum overcurrent protection to be marked on the controller. (See photo 8).
Photo 8. The maximum overcurrent protection that can be installed ahead of the group installation controller.
The second precaution to consider is the requirements of CE Code Rule 28-206. This rule directs code users to Rule 28-204 to limit the maximum overcurrent protection that can be installed ahead of the group installation controller.
For a feeder supplying motor branch circuits only, the ratings or settings of the feeder overcurrent device shall not exceed the calculated value of the overcurrent device permitted by Rule 28-200 for the motor that is permitted the highest rated overcurrent devices of any motor supplied by the feeder, plus the sum of the full load current ratings of all other motors that will be in operation at the same time.
As an example let’s look at a motor group installation consisting of five synchronous motors with full load ampacities (FLA) of 21, 2, 4, 7, 7, 7, and 16 A, and a main breaker installed ahead of the controllers marked suitable for group installation. (See table 1).
CE Code Rule 28-206 limits the circuit breaker ahead of the group installation to a maximum of 93 A 21x2.5=52.5 = 50 Amp breaker + (2+4+7+7+7+16). Note: the marking on the controller for Motor 2 limits the main circuit breaker to 80 A. As a result, this example for is not code-compliant. One option is to replace the Motor 2 controller with a group installation controller marked for a maximum 125 A circuit breaker and ensure the main breaker is not larger than 125 A.
The third precaution is the size of the circuit conductors including the tap conductors. The tap conductors are the conductors installed between the group installation controllers and the motors. CE Code Rule 28-106(3) limits the size of the tap conductor to not less than 1/3 that of the larger branch circuit conductor for the group of motors.
The minimum allowed ampacity of the branch circuit conductors for the group of motors in this example is 69.25 A, 21x1.25 + (2+4+7+7+7+16). From the 75⁰C column of CE Code Table 2, a 4 AWG copper conductor with the ampacity of 85 A has been selected. The following table shows the tap conductor sizes and percentages of the larger conductor for our example. (See table 2).
As you see, the Motors 2 to 6 have 14 AWG copper conductors with an allowable ampacity of 20 A that is less than 1/3 of the larger 4 AWG copper conductor allowable ampacity of 85 A. This can be made code-compliant by installing 12 conductor in place of the 14 AWG copper conductors, or separating the largest motor from the group reducing the main circuit breaker and larger conductor size. The following table shows the revised group without Motor 1. This group would now have a maximum main circuit breaker of 70 A, 16x2.5 = 40 Amp breaker + (2+4+7+7+7) and a minimum conductor allowable ampacity of 47 A, 16x1.25 + (2+4+7+7+7). Resulting in a 8 AWG copper conductor as the larger conductor supplying the group installation controllers. (See table 3 ) .
The final precaution to consider is the length of the tap conductors. CE Code Rule 28-106(3) limits the length of the tap conductors to a maximum of 7.5 m. The following table shows our revised example detailing the tap conductor lengths proposed. (See table 4).
As you can see the length of the tap conductor for Motor 4 is not code-compliant. If the conductor cannot be rerouted to limit the length of the tap conductor to 7.5m, individual overcurrent would need to be installed ahead of the tap for Motor 4.
The limitations when grouping motors on a single overcurrent device include the method of motor overload protection, short circuit protection for the motor branch circuit conductors, controllers and motors, size of the tap conductors, and the length of the tap conductors. The overload protection can be in the form of integral protection for the motor or remote overload protection as part of the control equipment. The maximum overcurrent device used to provide the short circuit protection for the motor branch circuit conductors, controllers, and motors must not exceed the limitations of Rule 28-206 and cannot exceed the maximum rating permitted by the rating marked on the group installation motor controller. The motor tap conductors must have an allowable ampacity not less than 125% of the motor full load ampacity. The motor tap conductor allowable ampacity must also be greater than 1/3 that of the larger conductor installed ahead of the group installation motor controller, and the maximum length of the motor tap conductor cannot exceed 7.5m.
Read more by Steve Douglas
Posted By Jesse Abercrombie,
Monday, September 16, 2013
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If you own a business, you may well follow a "do it now” philosophy; which is, of course, necessary to keep things running smoothly. Still, you also need to think about tomorrow, which meansyou’ll want to take action on your own retirement and business succession plans.
Fortunately,you’ve got some attractive options in these areas. For example, you could choose a retirement plan that offers at least two key advantages: potential tax-deferred earnings and a wide array of investment options. Plus, some retirement plans allow you to make tax-deductible contributions.
In selecting a retirement plan,you’ll need to consider several factors, including the size of your business and the number of employees. If your business has no full-time employees other than yourself and your spouse, you may consider a Simplified Employee Pension (SEP) plan or an owner-only 401(k), sometimes known as an individual or solo 401(k). Or, if your goal is to contribute as much as possible, you may want to consider an owner-only defined benefit plan.
If you have employees, you might want to investigate a SIMPLE IRA or even a 401(k) plan. Your financial advisor, working with plan design professionals and your tax advisor can help you analyze the options and choose the plan that fits with your combined personal and business goals.
Now, let’s turn to business succession plans. Ultimately, your choice of a succession plan strategy will depend on many factors, such as the value of your business, your need for the proceeds from the sale of the business for your retirement, your successor, and how well your business can continue without you. If your goal is to keep the business within the family,you’ll need to consider how much control you wish to retain (and for how long), whether you wish to gift or sell, how you balance your estate among your heirs, and who can reasonably succeed you in running the business.
Many succession planning techniques are available, including an outright sale to a third party, a sale to your employees or management (at once or over time), or the transfer of your business within your family through sales or gifts during your life, at your death or any combination thereof.
Many succession plans include a buy-sell agreement. Upon your death, such an agreement could allow a business partner or a key employee to buy the business from your surviving spouse or whoever inherits your business interests. To provide the funds needed for the partner or employee (or even one of your children) to purchase the business, an insurance policy could be purchased.
Your estate plan — including your will and any living trust — should address what happens with the business, in case you still own part or all of it at your death. The best-laid succession plans may go awry if the unexpected occurs.
All these business succession options can be complex, so before choosing any of them, you will need to consult with your legal and financial advisors.
Whether it’s selecting a retirement plan or a succession strategy,you’ll want to take your time and make the choices that are appropriate for your individual situation.
You work extremely hard to run your business, so do whatever it takes to help maximize your benefits from it.
Read more by Jesse Abercrombie
Posted By Christel Hunter,
Monday, July 01, 2013
Updated: Thursday, June 20, 2013
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Electrical systems are typically given a great deal of consideration during the design and installation phase of new construction or major renovation, but very little thought after completion — until something fails. Even though our electrical systems are usually very reliable, it is likely that some components will need maintenance or testing at some point in the life of the building or structure. Therefore, the NEC contains requirements meant to allow for safe and practical access to electrical equipment after the time of installation.
In the NEC, working space requirements are found primarily in Article 110. NEC 110.26 applies to electrical equipment operating at 600 volts or less. The primary requirement is that both access and working space must be provided and maintained for all electrical equipment. (Photo 1). This is to allow for ready and safe operation and maintenance of the equipment.
Photo 1. Code violation of 110.26
The definition of equipment in the NECis "a general term, including fittings, devices, appliances, luminaires, apparatus, machinery, and the like used as a part of, or in connection with, an electrical installation.” This is a very broad definition, and when put in the context of working space requirements, likely includes many items not usually thought of when applying the requirements of 110.26.
After the first paragraph, Section 110.26 is divided into six subsections identified as (A) through (F). Section 110.26(A) defines the required height, width and depth of working space according to the voltage and type of equipment being considered. These requirements are specific to equipment "likely to require examination, adjustment, servicing, or maintenance while energized.”
Depth of working space is covered in 110.26(A)(1) and the associated table. The question is often asked, "Where do we start the measurement — from the live parts, the dead front, or the cover?” The NEC tells us that the measurement must begin from the exposed live parts, unless the live parts are enclosed. If they are enclosed, the measurement begins from the enclosure or opening.
Table 110.26(A) has three conditions for determining the minimum clear distance. (Figure 1). Condition 1 applies either when there are exposed live parts on one side of the working space and no live or grounded parts on the other side of the working space, or when there are exposed live parts on both sides of the working space that are effectively guarded by insulating materials. For Condition 1 installations with voltages to ground up to 600 volts, the minimum clear distance is 3 feet.
Condition 2 applies when there are exposed live parts on one side of the working space and grounded parts on the other side of the working space. The code explicitly states that concrete, brick or tile walls shall be considered as grounded. For Condition 2 installations with voltages between 0 and 150 volts, the minimum clear distance is 3 feet. For voltages between 151 and 600 volts, the minimum clear distance is 3.5 feet.
Condition 3 applies when there are exposed live parts on both sides of the working space. For this condition and voltages between 0 and 150 volts, the minimum clear distance is again 3 feet; while for voltages between 151 and 600 volts, the required distance is 4 feet.
Certain installations are allowed exceptions from the minimum depth requirements. For assemblies such as dead-front switchboards and motor control centers where all the connections and renewable or adjustable parts are accessible from locations other than the back or sides, there is no working space required for the back or sides of the equipment. If there are nonelectrical parts of such equipment that require rear access to work on them, a minimum horizontal working space of 30 inches is required.
Certain low voltage installations also have less required working space. If all the exposed live parts operate at not greater than 30 volts RMS, 42 volts peak, or 60 volts dc, then the inspector is allowed to grant special permission for a reduced working space. The definition of special permission in the NEC is "the written consent of the authority having jurisdiction,” so be sure to get it in writing! The specific amount of working space for these installations is not indicated, so it is up to the installer and the AHJ to work together to determine the safe amount of working space.
The NEC provides an allowance for existing buildings, as well. Where there are dead-front switchboards, panelboards, or motor control centers across an aisle from each other that are being replaced in an existing building, the Condition 2 distances are allowed instead of Condition 3. This only applies if there is maintenance and supervision of the building to ensure that written procedures have been adopted to: 1) prohibit equipment on both sides of the aisle from being open at the same time and 2) ensure that only authorized qualified persons are allowed to service the installation.
Width of working space is simpler to determine than depth; it is required to be the width of the equipment or 30 inches, whichever is greater. So if you have three 20 inch wide panelboards mounted on the same wall next to each other, what is the required working space? Since there is no prohibition against equipment sharing the width of working space, it could technically be as little as 60 inches. However, this is neither practical (for mounting reasons) nor prudent. It is a better practice to provide spacing between equipment and not to place a piece of equipment right up against a perpendicular wall, since this might make it more difficult to service in the future.
Remember that the requirements in the NEC are minimums; you are always allowed to make an installation safer and better. Note that the working space must also allow at least a 90 degree opening of equipment doors or hinged panels, so that might come into consideration depending on the design of the equipment.
Height of working space is measured from the grade, floor, or platform, and is required to be at least 6.5 feet or the height of the equipment, whichever is greater. If there is electrical equipment that is associated with the electrical system located above or below a piece of equipment, it is allowed to extend no more than 6 inches into the required working space.
There are two exceptions to the base requirement for height of working space. The first is for existing dwelling units, where panelboards, or service equipment, that do not exceed 200 amperes are allowed in working space that is less than 6.5 feet. (Quick fact: individual meter socket enclosures are not considered service equipment per 230.66.) The second exception is new to the 2011 NEC and states that meters that are installed in meter sockets shall be permitted to extend beyond the other equipment, but the meter socket is still required to follow the rules of this section. (Figure 2).
Moving on from the working space requirements, our next requirement is in 110.26(B) for clear spaces about electrical equipment. The required working space is not to be used for storage. No mops, no boxes, no stock, etc. As shown in photo 2, this is a commonly violated code rule. Additionally, if equipment is located in a passageway or general open space, it must be suitably guarded if any normally enclosed live parts are exposed for inspection or servicing.
The next few requirements cover entrance to and egress from the required working space. The minimum requirement is that at least one entrance of sufficient area must be provided. This is both to allow access to the equipment and egress from the working space about electrical equipment. Although "sufficient” is considered to be a "possibly vague or unenforceable” word in the NEC Style Manual, it is hard to think of a better word that would be inclusive of all the potential electrical equipment installations.
Large equipment has special requirements. For the purposes of these requirements, large equipment is defined as equipment rated 1200 amperes or more and over 6 feet wide that contains overcurrent devices, switching devices, or control devices. For this equipment, at least one entrance to and egress from the required working space is required at each end of the working space, and each entrance must be at least 24 inches wide and 6.5 feet high.
Photo 2. Code violation of 110.26(B)
There are two exceptions to the requirement for multiple entrance/egress points. The first is when there is a continuous and unobstructed path of egress; in that case a single entrance is permitted. For example, if the equipment is on the wall directly opposite an entrance door and there is nothing between the two, this may be permitted as the single entrance.
The second exception is when there is extra working space. (Figure 3). If the depth of working space is twice that required by 110.26(A)(1), a single entrance is permitted. The distance to the nearest edge of the entrance from the equipment must be not less than the minimum clear distance as specified in Table 110.26(A)(1), based on the voltage and condition present. The idea behind this exception is to allow enough space for the electrician to get far enough away from the equipment to avoid being trapped if there is a problem in the equipment between the electrician and the exit.
Personnel doors also have special requirements for installations with equipment rated 1200 amperes or more that contains overcurrent devices, switching devices, or control devices. If the door is intended for entrance to and egress from the working space and the door is less than 25 feet from the nearest edge of the working space, then the door has to open in the direction of egress. It must also have panic bars, pressure plates, or other devices that are normally latched but open under simple pressure. (Photo 3).
Photo 3. Example of personnel doors with appropriate opening hardware
Illumination is obviously important for anyone working on electrical equipment. The NEC requires that illumination be provided for all working spaces around service equipment, switchboards, panelboards, or motor control centers installed indoors. New for the 2011 NECis the specific requirement that this required illumination shall not be controlled by automatic means only. (Figure 4). If the working space is illuminated by an adjacent light source or as permitted by 210.70(A)(1), Exception No. 1 for switched receptacles, then additional lighting outlets are not required.
Switchboards, panelboards, and motor control centers must be located in dedicated spaces and protected from damage. The only exception to this rule is for control equipment that for some reason (either because of its use or other code rules) must be adjacent to or within sight of its operating machinery. There are separate code requirements for indoor and outdoor dedicated equipment space.
Indoor installations must comply with four conditions including rules for dedicated electrical space, foreign systems, sprinkler protection, and suspended ceilings. The dedicated space requirement states that an area equal to the width and depth of the equipment and extending from the floor to a height of 6 feet above the equipment or to the structural ceiling (whichever is lower) must be dedicated to the electrical installation. This prohibits piping, ductwork, leak protection apparatus, and any other equipment that is not associated with the electrical equipment from being located in this space.
Some foreign systems are allowed above the dedicated space, but only if protection is provided to prevent damage to the electrical equipment from condensation, leaks, or breaks in the foreign system. (Figure 5). Sprinkler protection is permitted for the dedicated space, as long as the piping does not enter the required dedicated electrical space and is protected against leaking.
Dropped, suspended, or similar ceilings that do not add strength to the building are not considered structural ceilings. Suspended ceilings with removable panels are permitted within the dedicated electrical space.
Electrical equipment installed outdoors must be installed in suitable enclosures and protected from accidental contact by unauthorized personnel, vehicular traffic, and accidental spillage or leakage from piping systems. All of the working space requirements in 110.26(A) still apply, and there is a further requirement that no architectural parts or equipment are allowed to be located in the working space.
The last section of 110.26 deals with locked electrical equipment rooms or enclosures. If an electrical equipment or room is locked, it is considered accessible to qualified persons. The definition of accessible(as applied to equipment) in Article 100 is "admitting close approach; not guarded by locked doors, elevation, or other effective means.” The language in 110.26(F) is a way to reconcile the requirement of 110.26 that access is to be provided to electrical equipment, while also allowing for locked rooms to protect equipment from unqualified persons.
There are additional requirements for equipment above 600 volts, including 110.32, 110.33 and 110.34. Many of the base requirements are very similar to those for equipment operating at 600 volts or less, and I encourage you to read those sections if you design, install or inspect equipment rated at higher than 600 volts.
It can seem difficult to find adequate space for electrical equipment due to construction limitations in new buildings or existing buildings; however, the working space requirements are necessary for the safety of maintenance personnel and service electricians. While it is always recommended to de-energize equipment before working on it, there are certain operations (especially testing) that require accessing live parts. The working space requirements provide adequate space for working safely on the equipment and for egress away from the equipment in the case of an abnormal condition.
Read more by Christel Hunter
Posted By Steve Foran,
Monday, July 01, 2013
Updated: Thursday, June 20, 2013
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Last summer my wife and I moved into a neighborhood close to where we both grew up. The deck railing on our new home was too low and took away from the appearance of the house. We decided to replace it with an updated railing system. We were looking for something a little different but not too extravagant, and within our budget. We found a creative young woodworker who specializes in unique projects.
After we hired him, the engineer came out in me. The craftsman and I had many conversations about various layouts, designs and the intricate details of making it all come together.
In one of the early discussions we identified a challenge in how the two rails would meet together in the corner. He hadn’t run up against this particular situation before and obviously, as an armchair deck builder, neither had I. We agreed to think about it and meet again the next day to make the final decision.
You know how your mind focuses when something captures your attention. Well, I was consumed by this problem. To me, it was an engineering challenge. On and off for the next 10 hours or so, I tried to visualize how to make it work. Then out of the blue, the solution came to me.
I sketched the design on a piece of paper. Yup, I figured it out! I was excited about having the answer and proud of unlocking the puzzle.
The next day at our progress meeting I began abruptly, "I figured out the corner thing.” I then went on to explain all the details of how to build the corners. I even told him how I came to the solution and how much time I spent thinking about it.
When I was done speaking, I looked at him and thought, "Oh my goodness, what have I done?” He had a polite, forced smile on his face. It was like I had taken the wind out of his sails.
I had not asked how he was doing or if he had any thoughts on how to tackle the problem. I was so focused on myself; I just dove headlong into my idea.
I realized that in my excitement I broke one of the cardinal rules in dealing with people. I acted in a way that did not appreciate his skills and abilities and in doing so slighted his dignity. My solution was right, but the way I was right was wrong. After I realized what happened, I apologized. He appreciated that and explained that he had not taken offense. Again, he was very generous.
My actions were not deliberate but that does not matter. If we expect people to give the best of themselves, we must acknowledge and honor the best in them. This begins by allowing people to use their gifts and talents and then by resisting the temptation to rescue someone at the first sign of a challenge, unless of course the risk of inaction demands you act. As difficult as it can be, you must recognize that "standing by” is sometimes necessary even when you have the answer or think you do.
Read more by Steve Foran
Posted By Randy Hunter,
Monday, July 01, 2013
Updated: Thursday, June 20, 2013
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Well we’ve made it to chapter three of the National Electrical Code. I like to refer to this area of the code as the "nuts and bolts” of an electrical installation. Chapter 3 is entitled Wiring Methods and Materials, and it covers much of the mechanical portion of the code. This includes what materials we use, how to install them and where. For those preparing for a certification test, this is usually one of the key portions of the test for both open and closed book questions. In Article 300, almost every section is one you need to know to do both good quality installations or to perform thorough inspections of basic electrical systems. This article starts with some very basic items, but it is important that we cover these; so we are going to take our time and thoroughly go through several of the requirements in detail. In 300.1, we find General Requirements which include practices used throughout the code (unless specifically modified elsewhere) along with a short explanation that this article doesn’t apply to the integral parts of equipment, such as motor controllers or similar items. The last general item is Metric Designators and Trade Sizes, which includes a table of the sizes recognized in the NEC. Limitations are covered in 300.2, which includes voltage and temperature. Wiring methods in Chapter 3 shall be 600 volts unless specifically indicated otherwise. Temperature limitations of conductors will be covered in Article 310 where we get specific regarding conductors.
Continuing into 300.3 Conductors, in part (B) we find one of the basic rules regarding conductor arrangements. Basically, all the conductors of the same circuit and the equipment grounding conductor, if used, must be contained within the same raceway, gutter, cable tray or other items listed there. I know to some this will be a basic rule and you may ask why it even has to be mentioned in the code; however, it is a critical installation requirement. If installations don’t comply with this, some of the resulting problems may include poor power quality, harmonics and induction heating, which may lead to overheating of the conductors. Worse yet, if you are in a non-metallic raceway and damage occurs to one of the conductors and the equipment grounding conductor isn’t present, there may be no low impedance ground path allowing overcurrent protection devices to operate before further damage occurs to the system. This article continues into four subsections, which details some specific variations. The most common one to be familiar with is the paragraph that talks about Parallel Installations. These requirements are violated all too often, as you can see by some of the attached photos.
Photo 2. As mentioned in 300.3(B), conductors of the same circuit shall be in the same raceway. As simple as that sounds, you can see from these two photos that it is not always done. Two good code violations are shown here.
Conductors of Different Systems are covered in 300.3(C). This is a code section that is often missed by inspectors, especially ones who have not had a lot of commercial experience. In (C)(1) we find the conditions that must be followed for systems 600 volts or less; this is the one that causes most of the enforcement issues, as anything over 600 volts we generally have an eye out for since those systems are less common. When we deal with some of the new technologies that are out there for lighting control systems, we often find the controls are utilizing low-voltage signal wire or CAT 5 or 6 cable systems. The code requires that all the conductors within a cable, enclosure or raceway have a minimum rating of the maximum voltage applied to any one conductor within. So if we have a facility that is using a 480/277-volt system that is feeding the lighting system at 277 volts, then all conductors at the same location must be rated for a minimum of 277 volts.
Protection Against Physical Damage (300.4) is broken down into eight specific types of installations, and we will explore some of these in detail. So what are we worried about that could damage our systems? Nails, screws, and various other materials that may penetrate the finished wall after the building is occupied, or during a remodel or renovation. During any electrical inspection, this is the most time-consuming portion of the inspection process, as you must visually look at almost every foot of an installation, no matter what method is being used. So starting with part (A) Cables and Raceways through Wood Members, first we have Bored Holes. The rule here is that any bored holes must be 1¼″ from the nearest edge of the wood member. Why do we pick 1¼″ ? Well, most of the wall finish components, both interior and exterior, have attachment requirements which require about a ⅞″ penetration. So you can see we have a ⅜″ safety margin in an ideal world. Normal 2″ x 4″ wood framing members actually have only a 3 ½″ width for the electricians to work with, so let’s do a little math. If you take the required clearance from each side, which adds up to 2 ½″, that leaves an electrician 1″ for a bored hole. The bits commonly used range in diameter from ½″ to 1 ¼″. I used to have my employees use ¾″ bits to give a bit of a fudge factor in location.
Photo 3. Here is an example of very poor stud boring locations, resulting in several conditions where we don’t have our 1-1/4" clearance requirement.
The other issue with the boring bits is the length they come in; many electricians like to use bits that are 18″ in length, as it allows them to extend their reach. However, when you put an 18″ bit into a drill and add the length of the drill which is 6″ if using a right angle drill, you now have an assembly that is 2' long. This won’t fit nicely between framing members, which are normally spaced 16″ or 24″ on center. This often results in angled holes being bored, many times creating a violation of the 1¼″ code requirement. So what do we do? The code goes on to say that if the 1¼″ requirement isn’t met, then you are to provide some other form of protection. This protection is accomplished by installing a steel plate that is a minimum of 1/16″ thick, which has to be the appropriate width and length to cover the area of wiring. There are two exceptions here, one that excludes rigid metal conduit, intermediate conduit, rigid non-metallic conduit and electric metallic tubing. It is felt that these methods are robust enough on their own to afford the needed protection; however, I have seen nail guns shoot nails right through rigid non-metallic conduit (PVC). The second exception is that you are allowed to use a listed and marked steel plate that is less than the required 1/16″ as long as it provides equal or better protection.
Photo 4. On the left, we have a case of angle drilling which has created an exposed area for the cable as outlined in the photo. On the right, we have the inspector checking a similar installation which has been properly protected.
One item I must mention here is that the framers often have a procedure they call "shim and shave.” This is their attempt to build nice straight walls. The issue here is that what may have been a bored hole that made the code requirements when made, may not be after they have shaved a ½″ off the face of a stud to straighten the wall. As a result of this, we would ask the builders not to call in for a rough inspection until after the shim and shave was done. Also, during this process, they often damage boxes, remove boxes or damage cable assemblies. So as you can see, it is best to do the inspection after all the trades are done and just before the wall coverings are installed. Personally, I used to use a 6″ long ¾″ bit and always paid careful attention to the location of my bored holes when I was in the field for two reasons: first, the finished job looked better; and second, the cost of the nail plates added up fast if you made a habit of missing.
The next paragraph deals with notches in wood and the protection needed if using notches. First, verify with the engineer that it is ok to notch the wood member, since notching can lead to a lack of structural strength. If notching is allowed, again we must protect the installation with a1/16″ plate as described above and with the same exceptions.
Continuing with protection in (B), we find Non-metallic Sheathed Cables and Electric Nonmetallic Tubing through Metal Framing Members. Here we must provide protection for these two types of wiring methods through steel studs. The first requirement is for nonmetallic-sheathed cable installations in steel studs. Steel studs come with factory punched holes through which we can pass this cable; however, at times these are not in the exact location we need, so we can also punch or cut our own holes. Either way, we must protect these wiring methods from the sharp edges of the steel studs. This is done by using listed grommets or bushings that cover all the metal edges through which we are passing; and, of course, they must be installed before the cable is pulled.
Photo 5. As mentioned in the article, you have to look at every foot of the installation to watch for areas where damage may occur or has occurred, as can be seen above. The cable installed over the gang nail has scraped the outer sheath off down to the actual conductors.
A personal story here: while I was inspecting tract homes being built by one of the largest builders in the country during the 1990s, they decided to change from wood framing to steel framing due to the rise in lumber cost. The electrical contractor had only done residential work and had never done steel framing. The result was a learning process which resulted in a slowdown of the project until they were able to improve their practices. In addition to just passing through the punched holes, the cable was also being damaged where it was pulled around corners of framing members where it didn’t actually pass through a stud, but got pulled tight against a perpendicular metal framing with very sharp edges. Since this increased inspection times to carefully inspect the installation, the contractor soon found ways of installing protective guards on the edges and then secured it with cable ties, keeping the cable in place to provide a good installation.
In 300.4(B)(2), we find similar language to that covered above regarding the penetration of nails or screws; again, we have to provide steel plates for protection.
Now we are going to skip to 300.4(D), which deals with installations parallel to framing members or furring strips. Furring strips are building materials that are not the usual dimensions of framing members. For example, if you are finishing off a concrete basement and want to add drywall to convert it into living space, it is common to install 2″ x 2″ furring strips to attach the drywall. In order to make a code-compliant electrical installation, we have to add receptacle and switches, so we notch the furring strips to pass through the cable. We must provide protection for the cable if it is within 1¼″ to the face of the furring strips. Often we will find the cable run in a piece of electric metallic tubing (EMT) to provide the protection required.
Photo 6. The above is an excellent installation providing proper protection of the cables, while not making numerous holes in the structural top plate of the wall. Also, please note the cable installed on the left where we have protection plates at the top plate and cable retention devices keeping the cables positioned the required distance from the face of the studs.
Moving on to 300.4(E), which was new to the 2008 and again modified in the 2011 code, we have requirements for Cables, Raceways or Boxes installed in or under corrugated roof decking. You will notice the unique language used here, "installed in or under,” leaving you no doubt that you aren’t allowed to have it within the upper channel of the decking. In fact, the wiring methods shall be at least 1½″ below the bottom corrugation. The main reason for this is that when the roofing underlayment is being installed, oftentimes the roofers use different thicknesses of material. In order to fasten the material in place, they have fasteners much like nails of different lengths. So as they work their way across a roof, they don’t always adjust the length of the fasteners, which means we get over-penetrations which could lead to damage to our electrical systems. If the electrical components are in the upper corrugation, you are almost certain to get damage.
In 300.4(G), I must mention a minor modification to Insulated Fittings: they must be identified for the use. These are the bushings and smooth rounded-edge fittings that provide protection for the conductors against damage to the insulation. Also in paragraph two, we have a simple note that an insulating material shall not be used to secure the fitting or raceway, meaning it is not to be used in place of a lock nut. I wouldn’t think that would need to be mentioned, but from time to time we would see this violation. Also, the temperature rating of the insulator shall match the temperature rating of the conductors.
The last portion of 300.4 we are going to cover is (H), which is Structural Joints. Structural joints are basically seams within building structures where we have a small separation or gap. As these two different parts are allowed to move separately for expansion and contraction, a rigid raceway system would pull apart or crush itself where it crosses the gap. Therefore, we need some form of flexible fitting that can absorb this movement. The code gives us two ways to do this, either by a listed expansion/deflection fitting or by an approved means, meaning something that is acceptable to the AHJ. Usually this is done by a piece of flexible raceway installed at the expansion joint with a little excessive length to allow for movement. If using a listed fitting, make sure it is listed for the raceway system you are using; don’t use a unit listed for rigid galvanized conduit only when you are using electrical metallic tubing.
Next we move to 300.5, Underground Installations.Our major concern with underground installations is the depth required to install the method we have chosen to use. These depths are listed in Table 300.5, but first we need to cover some basics. One is that all underground installations are considered to be wet locations. So make sure that the conductors are listed for wet locations, and recognize that this may limit you on the ampacity of some conductors. The reason for this is that no matter what part of the country we are in, at the very least we will have condensation within the raceways. Underground conduits commonly collect water — yes, even in the desert! Cables installed under buildings are to be in conduit unless they are MI cable or PVC jacketed MC cable.
In 300.5(D) and (E), Protection from Damage and Underground Splices are covered; please read these as they are well detailed. We will skip to (F), Backfill, as this is an item that frequently must be watched carefully. Often those doing the backfill are not the electricians, and they don’t show the proper respect to the systems we have installed. This is very hard for the inspector, as we inspect the system to make sure they have the required depth and the proper installation for the system used, but we don’t have time to stand by and watch the backfill process. You will have to work out a system that works for you. When gas lines for swimming pools were installed in the Las Vegas area, we made the contractor have sand on site in order for us to sign off the inspection. I’m not suggesting this for you, it is just an example and the system we used. If you are dealing with direct burial conductors or cables, the back fill is very important, as any sharp or abrasive material could damage the insulation or jacketing.
The last item before we review the table will be (J), Earth Movement. This is for those installations where we have direct burial systems that may be subject to movement due to settlement or frost. We must allow for this movement so that we don’t pull the conductors out of the termination points or pull the equipment off the wall. The movement is often compensated for by the installation of a slip-fit riser and a loop in the conductors to permit movement without damage to the equipment or conductors.
Photo 7. Here we have an example of a basement being finished out with 1-1/2" deep furring members. Notice the protection of the cables through the wood members, but what about the protection of the vertical runs, which aren’t 1-1/4" from the face of the framing members?
We will end this article with a review of Table 300.5. In all honesty, I have never tried to memorize this table, as there are too many details that apply to each installation. In the left column, we find the location of the wiring method. The one we use most often is under a building, under streets, etc., and one- and two-family dwelling locations. Across the top we have wiring methods and, in some applications, voltages applied to the wiring method. Using this matrix we can find the minimum depth required by code.
The first one I will mention is under a building in the left column; as you read across, you will notice that the depths are zero. Does that mean you can just lay the conduit on top of the sub-grade before concrete placement? In my opinion the answer is no, since the concrete slab to me was part of the building and the code says under the building, not in the building. Also, structural engineers get a little fussy when electricians start to put conduits in their structural elements. Basically, if you have a conduit within a slab, you have created a thin spot in the slab and a location for a crack or fracture of that slab. So we would ask to have these raceways installed such that the top of the raceway was level with the top of the sub-grade.
Next, if you are doing work under a street, road, alley, driveway or parking lot, no matter what, you need 24″. Typically, any installation around a dwelling unit is 18″ unless you have a 120-volt GFCI-protected circuit, then you only need 12″.
If you have followed along with the table for the examples I just gave, you get the gist of how to use the table properly. Please note there are five notes to this table which may allow for modifications to the table. Unlike information notes, these notes are enforceable. I will mention only one and that is Note 5, which talks about solid rock and getting a depth reduction due to this. In the desert, we often have a cementitious soil called caliche, which is basically as hard as concrete or solid rock. Fortunately, the trenching people have developed equipment which cuts through even this and we haven’t had to use this allowance very often in the last decade.
This brings us to a good stopping point for now. As you can see, Article 300 has very important information that we must have a good working knowledge of as both inspectors and electricians. Please remember to read the sections covered, as we have just skimmed the top of these in the interests of time and space. In the next article, we will continue with Article 300.
Read more by Randy Hunter
Posted By Jesse Abercrombie,
Monday, July 01, 2013
Updated: Thursday, June 20, 2013
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Life is full of ups and downs; and the financial markets are no different. As an investor, you’re no doubt happy to see the "ups” — but the "downs” can seem like a real downer. Isn’t there any way to help smooth out the volatility in your investment portfolio?
First of all, to cope with volatility, it’s helpful to know what causes it; and there can be many causes. Computers that make trades in milliseconds, based on mathematical models, are sometimes blamed for intraday volatility, but large price swings can also occur following the release of government economic reports, such as those dealing with unemployment and housing starts. Global events, such as the European economic malaise, can also send the financial markets into a tizzy.
By being aware of the impact of these events, you can see that the workings of the markets — especially their volatility — may not be as mysterious as you thought. Still, while knowing the causes of volatility can help you prepare for market swings, it won’t blunt their impact on your portfolio. To do that, you need to create a diversified mix of investments because your portfolio can be more susceptible to negative price movements if you only own one type of asset.
To illustrate: If you owned mostly bonds, and interest rates rose sharply, the value of your bonds would likely drop, and your portfolio could take a big hit. But if you owned stocks, bonds, government securities, certificates of deposit (CDs) and other investment vehicles, the rise in interest rates would probably affect your portfolio less significantly.
Unfortunately, many investors think that if they own a few stocks and a bond, they’re diversified. But you can actually extend your diversification through many levels — and you should. For the equity portion of your portfolio, try to own stocks representing many market sectors and industries. Also, consider international stocks. And rather than just owning U.S. Treasury bonds, consider corporate bonds and municipal bonds, and diversify your fixed-income holdings further by purchasing short-term, intermediate-term and long-term bonds. Work with your financial advisor to determine the mix of asset classes and investments that are appropriate for your financial goals and objectives.
How you ultimately diversify your portfolio depends on your risk tolerance, time horizon and long-term goals — there’s no one "correct” asset mix for everyone. And over time, your diversification needs may change. To cite one example, as you enter your retirement years, you may need to increase your percentage of income-producing investments while possibly reducing the amount of growth investments you own. These growth-oriented investments tend to be more volatile, and you may want less volatility during your retirement. However, even during retirement, you will need to own a certain percentage of growth investments to provide you with the growth potential you’ll need to stay ahead of inflation.
Keep in mind that diversification can’t guarantee a profit or protect against loss. Nonetheless, building a diversified portfolio may help take some of the volatility out of investing — so look for diversification opportunities whenever possible.
Read more by Jesse Abercrombie