Posted By Leslie Stoch ,
Saturday, May 01, 1999
Updated: Tuesday, August 28, 2012
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Usually we can assume that the rules of the Canadian Electrical Code are based on some basic principles, which don’t vary a whole lot — to minimize the possibilities of electrical fire and shocks. But are the rules ever in direct conflict with each other or their principles?
Thankfully, we don’t need to consider this question too often. Rules are generally written to be consistent with other rules and some firmly held electrical safety principles. However, Rule 14-l00(d) in the 1998 Canadian Electrical Code seems to have strayed some distance from the fold. Here is the new 1998 code rule:
"Each ungrounded conductor shall be protected by an overcurrent device at the pointwhere it receives its supplyof current and at each pointwhere the size of the conductor isdecreased,except that such protection shall be permitted to be omitted: (d) Where the conductor:
(i) Forms part of the only circuit sup- plied from a power or distribution transformer rated over 750 kV with primary protection in accordance with Rules 26-252(1), (2), and (3) and that supplies only that circuit; and
(ii) Terminates in a single overcurrent device with a rating not exceeding the ampacity of the conductor(s) in the circuit; and
(iii) Is protected from mechanical damage
The basic electrical safety principle provided in the code is pretty clear — we have to provide overcurrent protection for conductors at points of supply or where conductor size is reduced. Rule 14-100 gives us a few exceptions under some very controlled conditions. The reasoning — to ensure that unprotected conductors in buildings don’t create any undue electrical fire or shock hazards. This new sub-rule of Rule 14-100 seems to imply that these principles are now changed when the transformer primary voltage exceeds 750 volts.
What Rule 14-100(d) says — we can now run the secondary conductors from a power or distribution transformer as far as we like without overcurrent protection if the transformer primary voltage exceeds 750 volts. The conductor run must still be protected from damage and terminate in a single circuit-breaker or set of fuses which protect conductors at their current ratings.
It seems odd that sources of power should receive different treatment when they are larger (power and distribution transformers with primary voltages above 750 volts). Thisseems even less reasonable when we consider that Table 50 (for primary voltages above 750 volts) allows primary overcurrent protection up to 600%. This of course allows the same multiple of transformer secondary current at the transformer secondary. Add to that the fact that larger power and distribution transformers can deliver higher phase-to-phase and phase-to-ground fault currents, which are not easily detected or interrupted by the transformer primary side protection.
Other 1998 CEC rules appear to support the general principle that conductors must always be protected by properly sized overcurrent and/or ground fault protection, with some closely controlled exceptions. Some examples:
1) Rule 14-102 was originally written to provide ground fault protection, to prevent damage due to low level arcing ground faults in large services and feeders. Obviously, the effectiveness of ground fault protection is greatly reduced when conductors are allowed to travel a long distance through a building before reaching the point where they are protected.
2) Rule 6-206(e) specifies that that the main service box must be "as close as practicable to the point where the consumer’s service conductors enter the building.” Once again, this rule is designed to limit the length of wiring in a building and thereby limit the possibilities for unprotected arcing faults.
3) For the same reasons, Rule 14-100(b) only allows us to reduce wire sizes when conductor runs are restricted to maximum of 3 m and when installed in a totally enclosed raceway, armoured cable or metal-sheathed cable.
4) The same for Rule 14-100(c), which allows us to reduce wire size down to 1/3, but only up to 7.5m with mechanical protection.
5) Rule 14-100(f), a variation of Rule 14-100(c) allows us to reduce primary conductors to a transformer down to 1/3 as long as both the primary and secondary conductors are protected against damage and their total lengths limited to maximum 7.5 m.
If we can assume that all of these rules are designed to minimize the occurrences of arcing faults for unprotected conductors in buildings, why is Rule 14-100(d) so out of tune with the rest? I would be pleased to find out your answers to this puzzling question.
As in previous articles, you should consult the inspection authority in the province or territory as applicable for a more precise interpretation of any of the above.
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Posted By Underwriters Laboratories ,
Saturday, May 01, 1999
Updated: Tuesday, August 28, 2012
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Does a UL Listed electric sign require further inspection in the field?
Large signs do. Electric signs so large that shipment in one carton or fully assembled is impractical may be divided into sections. Each major subassembly bears an "Electric Sign Section” Listing Mark. Sign faces, trim and mounting hardware are not considered major subassemblies. Each sign has suitable installation instructions describing or illustrating the proper assembly, mounting and connection of sign sections. The acceptability of the assembled sections in the field, interconnections between sections and the connections to a branch circuit rests with the local authority having jurisdiction.
About Underwriters Laboratories: Underwriters Laboratories® (UL) is an independent product safety certification organization that has been testing products and writing Standards for Safety for over a century. UL evaluates more than 19,000 types of products, components, materials and systems annually with 20 billion UL Marks appearing on 66,000 manufacturers products each year. UL's worldwide family of companies and network of service providers includes 68 laboratory, testing and certification facilities serving customers in 102 countries. UL is also the only National Certification Body (NCB) for PV in North America and an OSHA-accredited Nationally Recognized Testing Laboratory (NRTL). For more information, visit www.UL.com/newsroom.
UL Question Corner
Posted By Underwriters Laboratories,
Saturday, May 01, 1999
Updated: Tuesday, August 28, 2012
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How does UL assess water-damaged electrical equipment?
Flooding and other natural disasters prompt many questions about water-damaged electrical equipment. Can the equipment be dried out? Are the circuit breakers and fuses safe to use? Can switchboards be re-energized?
Since flooding usually comes swiftly and unexpectedly, there isn’t always time to shut off electrical equipment. Shut-off switches and electrical control boxes, commonly installed in lower levels of buildings, are often submerged. Besides causing a big mess, water-logged equipment isn’t the only problem facing building owners after a flood. Silt, debris, oil, dissolved chemical substances and other water-borne contaminants can also damage electrical equipment. And, after flood waters recede, rapid mold growth occurs, chemically attacking electrical components.
When approached to investigate flood-damaged electrical equipment, UL investigates equipment on a case-by-case basis. UL considers many factors when providing a review to assess whether to replace or refurbish damaged equipment. These factors include the age of the equipment, the extent of water damage, and corrosion or sediment deposits found in the components.
While the ultimate decision to replace or refurbish equipment is left up to the local code authority and building owner, they can ask UL to visit the flood site to evaluate the equipment that may have been affected, and discuss what can be done to repair, refurbish or replace water-damaged electrical equipment.
After refurbishment and repairs have been made, the owner may ask UL to return to the site to re-evaluate refurbished equipment. Upon completion of this evaluation, UL issues a letter report identifying areas of non-compliance with UL requirements. A copy of this report is also provided to the code or regulatory officials for use in determining the equipment’s suitability for reconnection to the electrical supply. Results of any tests conducted on the refurbished equipment are also provided, if available.
The owner may also request UL to conduct a Field Evaluation or Field Investigation on new replacement equipment that is not UL Listed. A Field Evaluated Product Mark is affixed to equipment found in compliance with UL requirements. Only Field Evaluations result in issuance of a Field Evaluation Product Mark. At the conclusion of a Field Investigation, UL issues a letter report and provides a label to the local acceptance authority for application to the product. It may not always be physically or economically practical to repair or refurbish all equipment damaged during a flood. Consequently, code authorities or UL representatives may advise the building owner to replace damaged electrical equipment with new equipment.
Some cases also require UL to continue inspecting refurbished and repaired equipment over specified time periods to check for any residual degradation caused by flood exposure, or other contaminants not found during the initial inspection. Information gathered from these additional visits are included in separate letter reports and provided to the local code authorities.
UL cannot evaluate flood-damaged equipment for Listing, Classification or Recognition.
For more information about UL’s evaluations of flood-damaged electrical equipment, contact the following Field Evaluation coordinators at the UL office nearest you:
Midwestern United States
Bill Bartunek at (847) 272-8800, ext. 42564
Fax: (847) 509-6219
E-mail address: firstname.lastname@example.org
Eastern United States
Jimmy Wong at (516) 271-6200, ext. 22552
Fax: (516) 439-6045
E-mail address: email@example.com
Southern United States
Bob Eberhardt at (919) 549-1641
Fax: (919) 547-6021
E-mail address: firstname.lastname@example.org
Western United States
Mike Shulman at (408) 985-2400, ext. 32770
Fax: (408) 556-6062
E-mail address: email@example.com
Northwestern United States
Dom Kumandan at (360) 817-5604
Fax: (360) 817-6024
E-mail address: firstname.lastname@example.org
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UL Question Corner
Posted By Philip Cox ,
Saturday, May 01, 1999
Updated: Tuesday, August 28, 2012
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Known as the "keystone of the electrical industry,” the IAEI is a unique organization in which all members of the electrical industry can come together and participate as a group and deal with issues that affect both the industry and the general public. The success of the IAEI is due in part to inspector members going the extra mile and giving much of their own time to better the organization. They have worked hard to provide valuable education and to promote the adoption and enforcement of good electrical safety rules. Unfortunately, some people evidently are under the erroneous impression that because of the IAEI’s name, only electrical inspectors can be members. Not only can those who are not electrical inspectors be members of the organization, but they also can be very active and productive in achieving the goals of the IAEI.
Associate members of the IAEI have always been vital in the growth of the organization. While associate members are not eligible to hold all offices nor to vote on all matters of the IAEI, they in fact exercise most privileges enjoyed by inspector members. For reasons similar to those held by most professional and trade organizations representing a specialized area of skill or expertise, the IAEI must reflect the inspector’s view on such things as organizational positions on electrical code rules. Organizations representing other professions, trades, or crafts generally are effective in representing their members’ special views on electrical code rules and other matters. Each professional or trade organization representing its members’ perspective on matters helps provide valuable technical information and achieves a reasonable balance on such things as the formation and adoption of good electrical safety rules.
Associate members of the IAEI are also vital to its success. That may seem strange to some because associate members are usually part of other organizations dedicated to their own specialized interest. However, some of the strongest advocates of the basic principles upon which the IAEI stands are associate members. Chapters in certain areas have so few inspectors that it must depend on associate members to keep it strong and productive. Associate members are frequently involved in providing or arranging for educational programs that directly benefit IAEI members in general. Many associate members serve as secretary/treasurers of sections, section districts, chapters, and divisions. As covered in an earlier editorial, the role of secretary/treasurer is probably the most demanding and vital for the smooth operation of the IAEI. This in no way degrades the office of president. IAEI presidents are leaders and chief executive officers of their particular section, section district, chapter, and division However, their jobs are much easier where the secretary/treasurer has held the position for an extended time and can provide the president with support and guidance where necessary.
Some of the most productive sections, chapters, and divisions have reached that level because of hard work by associate members. In some locations, associate members have been primarily responsible for seeing that inspector meetings are planned and run well, for locating sources of needed training and arranging for it to be presented , and for numerous other activities that both stimulate interest and address code related needs of members. Associate members who avidly support the IAEI recognize that it is in their best interest for the IAEI to maintain its unbiased position in the industry. They know that if their work with the IAEI focuses only on their own special interest, the independent and unbiased position that is traditionally associated with the IAEI may very well be compromised and that would be detrimental for all its members. Associate members generally understand the importance of a strong IAEI and the support of qualified electrical inspectors. Inspector members also understand the importance of non-inspector members of the IAEI for several reasons and have a great appreciation for the significant work they do for the organization. Achieving the objectives of the IAEI is a joint effort. The IAEI truly is a "keystone of the electrical industry.”
Read more by Philip Cox
Posted By Robert Milatovich ,
Monday, March 01, 1999
Updated: Monday, August 27, 2012
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First a little history of the National Electrical Code (NEC) dealing with the title of Article 680 and the addition of Part E. Fountains. The title of Article 680 in the 1962 NEC was "Swimming Pools” and remained that until the 1971 NEC when the title was changed to "Swimming and Wading Pools.” Then in the 1975 NEC the title was changed to "Swimming Pools, Fountains and Similar Installations.” Fountains were added to Article 680 as Part D. In the 1981 NEC Article 680, Part D was changed to Part E of Article 680, with the section numbers being changed from Section 680-40’s to 680-50’s.
Photo 1. Permanent Fountain
Photo 2. Permanent Fountain
In the next few pages I will try to dissect Article 680, Part E. Fountains, to explain what it means and how I think it should be interpreted. I hope this will be of some value to you.
My comments are not the official interpretations of the 1999 National Electrical Code (NFPA 70) published by the National Fire Protection Association.
Part E. Fountains
680-50. General.The provisions of Part E shall apply to all permanently installed fountains as defined in Section 680-4. Self-contained, portable fountains no larger than 5 ft (1.52 m) in any dimension are not covered by Part E. Fountains that have water common to a pool shall comply with the pool requirements of this article.
[See photos 1, 2, 3, and 4].
Photo 3. The fountain in this picture is what is referred to as a self-contained, portable fountain no larger than 5 ft. in any dimension
Starting with Section 680-50. General, the provisions of Part E shall apply to all permanently installed fountains as defined in Section 680-4.
In the 1981 NEC the word "include” and the words "fountain, fountain pools, ornamental display pools, and reflection pools” were removed and the words "”shall apply to all fountains as defined in Section 680-1″ were added.
In the 1984 NEC the reference to "Section 680-1″ was changed to "Section 680-4.” The words "permanently installed” were added to the 1999 edition of the NEC.
When we look at 680-4. Definitions, we find the following definition: "Fountain. As used in this article, the term includes fountains, ornamental pools, display pools, and reflection pools. It does not include drinking fountains.” This new definition was added for the 1999 NEC.
Photo 4. Swimming pool with a fountain using the same water
This definition was the second sentence in Section 680-1. Scope. (FPN) of the 1996 NEC®, which read, "The term fountain as used in the balance of this article includes fountains, ornamental pools, display pools, and reflection pools. The term is not intended to include drinking water fountains.” The words "includes fountains, ornamental pools, display pools, and reflection pools” has been in this Section since the 1975 NEC.
The Section continues with "self-contained, portable fountains no larger than 5 ft. (1.52 m) in any dimension are not covered by Part E.” This was an exception to Section 680-1 in the 1978 NEC and remained an exception until the 1999 NEC.
The last sentence informs us that fountains that have water common to a pool shall comply with the pool requirements of this article. This sentence has been inSection 680-1. Scope.from the first time it appeared in the 1975 NEC.
Photo 5. Transformer meeting the requirements of Section 680-51
680-51. Lighting Fixtures, Submersible Pumps, and Other Submersible Equipment.
This Section has not changed since it was introduced in the 1975 NEC. [See photo 5]
(a) Ground-Fault Circuit-Interrupter.A ground-fault circuit-interrupter shall be installed in the branch circuit supplying fountain equipment unless the equipment is listed for operation at 15 volts or less and supplied by a transformer that complies with Section 680-5(a).
Subsection (a) was in the 1975 NEC when fountains were added to the NEC and informs us that a ground-fault circuit-interrupter (GFCI) shall be installed in the branch circuit supplying fountain equipment, (the remainder of this sentence was an exception until the 1999 NEC) unless the equipment is listed for operation at 15 volts or less and supplied by a transformer that complies with Section 680-5(a).
Photo 6. Underwater fixture with a guarded lens
When we look at Section 680-5, Transformers and Ground-Fault Circuit-Interrupter, in subsection (a) we find the requirements for transformers which states, "Transformers used for the supply of underwater fixtures, together with the transformer enclosure, shall be identified for the purpose. The transformer shall be an isolated winding type having a grounded metal barrier between the primary and secondary windings.”
(b) Operating Voltage.No lighting fixtures shall be installed for operation on supply circuits over 150 volts between conductors. Submersible pumps and other submersible equipment shall operate at 300 volts or less between conductors.
Subsection (b) was in the original submission for fountains in the 1975 NEC, and the first word in this paragraph was "No.”
In the 1981 NEC it was changed to "All.”
In the 1999 NEC it was changed back to "No.”
In the 1975 NEC the word "”at”" was placed before the word "over,” the words "circuits supplying” were placed in the second sentence and then were removed in the 1981 NEC. The words "not to exceed” were added before the words "300 volts” and the words "or less” were added after the words "300 volts” and removed in the 1981 NEC.
In the 1981 NEC the words "or less” were placed after the words "150 volts.”
Subsection (b) Operating Voltage,informs us that no lighting fixtures shall be installed for operation on supply circuits over 150 volts between conductors. (This would mean that the voltage between any conductors, be it two hot conductors, or a hot conductor and a grounded
Photo 7. Underwater fixture with a low-water cutoff
conductor, shall not have a voltage of over 150 volts. You can also find this requirement in Part B, Permanently Installed Pools, 680-20(a), General, Subsection 2). Submersible pumps and other submersible equipment shall operate at 300 volts or less between conductors. (This would mean that the voltage between any conductors, be it two hot conductors, or a hot conductor and a grounded conductor, shall not have a voltage of over 300 volts for submersible equipment.)
(c) Lighting Fixture Lenses.Lighting fixtures shall be installed with the top of the fixture lens below the normal water level of the fountain unless approved for above-water locations. A lighting fixture facing upward shall have the lens adequately guarded to prevent contact by any person.
Photo 8. Underwater fixture
Subsection (c) has remained the same since the addition in the 1975 NEC. [See photos 6, 7, and 8]
(d) Overheating Protection.Electric equipment that depends on submersion for safe operation shall be protected against overheating by a low-water cutoff or other approved means when not submerged.
In the 1993 NEC, in Subsection (d) the word "which” after the words "Electrical equipment” was changed to the word "that.”"
(e) Wiring.Equipment shall be equipped with provisions for threaded conduit entries or be provided with a suitable flexible cord. The maximum length of exposed cord in the fountain shall be limited to 10 ft. (3.05 m). Cords extending beyond the fountain perimeter shall be enclosed in approved wiring enclosures. Metal parts of equipment in contact with water shall be of brass or other approved corrosion-resistant metal.
Subsection (e) has remained the same since the 1975 edition of the NEC.
Subsection (e), Wiring, informs us that all electrical equipment shall be equipped with provisions for threaded conduit entries or be provided with a suitable flexible cord. The maximum length of exposed cord in the fountain shall be limited to 10 ft. (3.05 m) and cords extending beyond the fountain perimeter shall be enclosed in approved wiring enclosures. Metal parts of equipment in contact with water shall be of brass or other approved corrosion-resistant metal.
(f) Servicing.All equipment shall be removable from the water for relamping or normal maintenance. Fixtures shall not be permanently imbedded into the fountain structure so that the water level must be reduced or the fountain drained for relamping, maintenance, or inspection.
Subsection (f) has remained the same since the 1975 edition of the NEC.
Subsection (f) Servicing, informs us that all equipment installed in a fountain shall be removable from the water for relamping or normal maintenance. Lighting fixtures shall not be placed into the walls, the bottom, or permanently imbedded into the fountain structure so that the water level must be reduced or the fountain drained for relamping, maintenance, or inspection.
(g) Stability.Equipment shall be inherently stable or be securely fastened in place.
Subsection (g) has remained the same since the 1975 edition of the NEC.
Photo 10. Underwater junction box
Subsection (g) Stability, informs us that equipment shall be inherently stable or be securely fastened in place. Placing a fixture on its side, when it is designed to sit on the bottom of the fountain facing in the up direction would not be inherently stable.
680-52. Junction Boxes and Other Enclosures.
This Section has changed very little since it was introduced in the 1975 NEC. [See photos 9 and 10]
(a) General.Junction boxes and other enclosures used for other than underwater installation shall comply with Sections 680-21(a), (b), (c), (d) and (e).
Subsection (a) is the same as the 1975 edition of the NEC® with the exception of the requirements in Section 680-21(a), which originally told us that only (a) 1, 2 and 3 would apply to fountains which has remained the same until the 1999 NEC.
Subsection (a) informs us that all junction boxes and other enclosures used for other than underwater installation shall comply with the requirements of Sections 680-21(a), (b), (c), (d) and (e) which refers to "Junction Boxes and Enclosures for Transformers or Ground-Fault Circuit-Interrupters.”"
(b) Underwater Junction Boxes and Other Underwater Enclosures.Junction boxes and other underwater enclosures shall be submersible and:
(1) be equipped with provisions for threaded conduit entries or compression glands or seals for cord entry;
(2) be of copper, brass, or other approved corrosion-resistant material;
(3) be filled with an approved potting compound to prevent the entry of moisture; and
(4) be firmly attached to the supports or directly to the fountain surface and bonded as required.
Where the junction box is supported only by the conduit, the conduit shall be of copper, brass, or other approved corrosion-resistant metal. Where the box is fed by nonmetallic conduit, it shall have additional supports and fasteners of copper, brass, or other approved corrosion-resistant material.
Section 680-21(b) in the 1975 NEC stated, "Junction boxes and other underwater enclosures immersed in water or exposed to water spray shall comply with the following…”
In the 1981 NEC this was rewritten and the words, "immersed in water or exposed to water spray shall comply with the following…” were replaced with "shall be watertight…”
Photo 11. Sign in fountain
In the 1987 NEC the word "watertight” was changed to "submersible”"and Section 680-21(b)(3) was changed from "”shall be located below the water level in the fountain wall or floor. An approved potting compound shall be used to fill the box to prevent the entry of moisture; and…” to "be filled with an approved potting compound to prevent the entry of moisture; and…”
In the 1981 NEC Section 680-21(b)(4), the structure of the paragraph was changed by taking the first sentence and making it a paragraph under (b)(4), but not part of (b)(4) and rewording the last sentence by removing the first three words "The box must…”
Section 680-21(b), Underwater Junction Boxes and Other Underwater Enclosures, informs us that all junction boxes and other underwater enclosures shall be listed as submersible and;
(1) be equipped with provisions for threaded conduit entries, such as hubs, or a type of compression gland or seals used for cord entry;
(2) be of copper, brass, or other approved corrosion-resistant material;
(3) be filled with an approved potting compound (See U.L. Standard 746A and 746C) to prevent the entry of moisture into the enclosures; and
(4) be firmly attached to the supports or directly to the fountain surface and bonded as required.
Where the junction box is supported only by the conduit, (we have to look at Section 370-23(e) and (f) which states, an enclosure supported by a raceway shall not exceed 100 cubic inches in size, have threaded entries or hubs, and be supported by two or more conduits secured with 18 inches of the enclosure, the conduit shall be of copper, brass, or other approved corrosion-resistant metal. (This would not include conduits with a galvanized finish such as rigid metal or intermediate metal conduit.) Where the box is fed by nonmetallic conduit, it shall have additional supports and fasteners of copper, brass, or other approved corrosion-resistant material. (This would not include supports and fasteners with a galvanized finish.)
FPN: See Section 370-23 for support of enclosures.
This FPN tells us to look at Article 370, Outlet, Device, Pull and Junction Boxes, Conduit Bodies and Fittings; Section 370-23, Supports, which tells us how the enclosures are to be supported.
Section 680-53, Bonding, all metal piping systems associated with the fountain shall be bonded to the equipment grounding conductor of the branch circuit supplying the fountain.
In the 1975 NEC this Section was worded, "All metallic piping systems associated with the fountain shall be bonded to the electrical system ground as required in Article 250,” and a new FPN appeared as "See Section 250-95 for sizing of these conductors.”
In the 1987 NEC the word "metallic” was changed to "metal” and remains the same in the 1999 NEC.
In the 1999 NEC the words "electrical system ground as required in Article 250,” were replaced with the words "equipment grounding conductor of the branch circuit supplying the fountain,” and FPN was changed to "See Section 250-122 for sizing of these conductors.”
FPN: See Section 250-122 for sizing of these conductors.
In the 1975 NEC a new FPN appeared as "See Section 250-95 for sizing of these conductors.”
In the 1999 NEC the FPN was changed to "See Section 250-122 for sizing of these conductors.”
This FPN tells us to look at Section 250-122, Size of Equipment Grounding Conductors. This section tells us that the size of the equipment grounding conductor is sized for the Rating or Setting of the Overcurrent Device for that circuit.
Section 680-54, Grounding. The following equipment shall be grounded:
(1) all electric equipment located within the fountain or within 5 ft. (1.52 m) of the inside wall of the fountain
(2) all electric equipment associated with the recirculating system of the fountain
(3) panelboards that are not part of the service equipment and that supply any electric equipment associated with the fountain.
In the 1987 NEC®, in subsection (1) the words "located within the fountain or” were added after the words "all electric equipment.”
680-55. Methods of Grounding.
(a) Applied Provisions. The provisions of Section 680-25 shall apply, excluding paragraph (e).
In the 1981 NEC (a) added a heading, "Applied Provisions,” and the words "Paragraph (a) and (d) excluding Exception 3,” after the word "apply” was changed to "Paragraph (a) and (c) excluding Exceptions.”
In the 1984 NEC it was changed again to "excluding paragraph (e).”
In the 1999 NEC the word "following” was deleted before the word "provisions.”
Section 680-55(a) informs us to look at Section 680-25, Methods of Grounding, and we see that it shall apply to all fountains with the exception of (e) Cord-Connected Equipment, which shall not apply to fountains.
Section 680-55(b), Supplied by a Flexible Cord, electric equipment that is supplied by a flexible cord shall have all exposed noncurrent-carrying metal parts grounded by an insulated copper equipment grounding conductor that is an integral part of this cord. This grounding conductor shall be connected to a grounding terminal in the supply junction box, transformer enclosure, or other enclosure.
Subsection (b) has remained the same since the 1975 NEC with the exception of a new heading in the 1981 NEC "(b) Supplied by a Flexible Cord.”
Subsection (b) informs us that all electric equipment that is supplied by a flexible cord shall have all exposed noncurrent-carrying metal parts grounded by an insulated copper equipment grounding conductor and this grounding conductor shall be an integral part of this cord. This equipment grounding conductor shall be connected to a grounding terminal that is required in Section 680-21(d), Grounding Terminals, which requires that a number of grounding terminals shall be at least one more than the number of conduit entries in the supply junction box, transformer enclosure, or other enclosure.
680-56. Cord- and Plug-Connected Equipment.
(a) Ground-Fault Circuit-Interrupter. All electric equipment, including power-supply cords, shall be protected by ground-fault circuit-interrupters.
Subsection (a) has remained the same since the 1975 NEC.
Subsection (a) informs us that all cord- and plug-connected electric equipment, including power-supply cords, shall be protected by ground-fault circuit-interrupters (GFCI).
(b) Cord Type. Flexible cord immersed in or exposed to water shall be of the hard-service type as designated in Table 400-4 and shall be marked water resistant.
In the 1975 NEC, after the words "shall be” were the words "a water-resistant Type SO or ST.”
In the 1990 NEC the words "marked water-resistant” were added after the words "Type SO or ST.”
In the 1993 NEC the text was changed to the present wording by adding "of the hard-service type as designated in Table 400-4 and shall be marked water resistant” after the words "shall be.”
Subsection (b) informs us that all flexible cord immersed in or exposed to water in a fountain shall be of the hard-service type as designated in Table 400-4, Flexible Cords and Cables, and shall be marked water resistant.
(c) Sealing. The end of the flexible cord jacket and the flexible cord conductor termination within equipment shall be covered with, or encapsulated in, a suitable potting compound to prevent the entry of water into the equipment through the cord or its conductors. In addition, the ground connection within equipment shall be similarly treated to protect such connections from the deteriorating effect of water that may enter into the equipment.
Subsection (c) has remained the same since the 1975 NEC with the exception that the word "which” after the word "”water”" in the last sentence was changed to "that” in the 1993 NEC.
Subsection (c) informs us that the end of the flexible cord jacket and the flexible cord conductor termination within equipment shall be (sealed) covered with, or encapsulated in, a suitable potting compound to prevent the entry of water into the equipment through the cord or its conductors. In addition, the equipment ground connection within equipment shall be similarly (sealed) covered with, or encapsulated in, a suitable potting compound and treated to protect such connections from the deteriorating effect of water that may enter into the equipment.
(d) Terminations. Connections with flexible cord shall be permanent, except that grounding-type attachment plugs and receptacles shall be permitted to facilitate removal or disconnection for maintenance, repair, or storage of fixed or stationary equipment not located in any water-containing part of a fountain.
Subsection (d) has remained the same since the 1975 NEC, except for the deletion of the words "or pool” in the 1981 NEC.
Subsection (d) informs us that the connections with flexible cord shall be permanent for all cord-connected equipment located in any water-containing part of a fountain.
Fixed or stationary equipment not located in any water-containing part of a fountain which uses grounding-type attachment plugs and receptacles to facilitate removal or disconnection for maintenance, repair, or storage.
In the 1975 NEC there was a "Section 680-47. Equipment Rooms.”
In the 1981 NEC this was moved to "680-11. Equipment Rooms. Electric equipment shall not be installed in rooms which do not have adequate drainage to prevent water accumulation during normal operation or filter maintenance.”"
In the 1984 NEC the words "and Pits” were added to the heading of "Section 680-11″ and after the word "rooms” and remains the same in the 1999 NEC.
Sign in a Fountain
This Section is new for the 1999 NEC because of the increasing use of advertising signs being installed inside of or being part of the fountains. [See photo 11]
(a) General. Includes only fixed, stationary electrically illuminated utilization equipment with words or symbols designed to convey information or attract attention.
Subsection (a) identifies what is covered by Section 680-57. If we look at Article 100, Definitions, you will see: "Electric Sign: A fixed, stationary, or portable self-contained, electrically illuminated utilization equipment with words or symbols designed to convey information or attract attention.” As you can see the definition of an electric sign contains the words "portable self-contained” which are not part of this requirement.
(b) Ground-Fault Circuit-Interrupter Protection for Personnel. All feeders or circuits shall be protected by ground-fault circuit-interrupters protection for personnel.
Subsection (b) informs us that all feeders or circuits supplying a sign installed in a fountain shall be protected by ground-fault circuit-interrupters (GFCI) protection for personnel, which means that the ground-fault circuit-interrupters (GFCI) are to be a Class A type, with a ground fault trip threshold of 6mA maximum.
(c) Location. Any sign installed inside a fountain shall be at least 5 feet inside the fountain measured from the outside edges of the fountain.
Subsection (c) informs us that any sign installed inside of a fountain shall be at least 5 feet inside of the fountain and that this is to be measured from the outside edges of the fountain to any part of the sign or sign structure.
(d) Disconnect. Shall comply with 600-6.
Subsection (d) informs us that the disconnect shall comply with Article 600. Electric Signs and Outline Lighting, Section 600-6 Disconnects, which tells us that the disconnect shall be located in accordance with Section 680-12, Disconnecting Means. (A disconnecting means shall be provided and be accessible, located within sight from all pools, spas, or hot tub equipment, and shall be located at least 5 ft. (1.52 m) horizontally from the inside walls of the pool, spa, or hot tub.)
Section 680-12. Disconnecting Means, refers to pools, spa, or hot tubs, but with this reference to Section 680-12, it now also applies to fountains.
This Section tells us that a disconnecting means shall: be provided (Installed), and be accessible (See Article 100, Definitions, Accessible (as applied to equipment). Admitting close approach; not guarded by locked doors, elevation, or other effective means.) and be located within sight from (See Article 100, Definitions, In Sight From (Within Sight From, Within Sight): Where this Code specifies that one equipment shall be "in sight from,” "within sight from,” or "within sight,” etc., of another equipment, the specified equipment is to be visible and not more than 50 ft (15.24 m) distant from the other.) all pools, spas, or hot tub equipment, and be located at least 5 ft (1.52 m) horizontally from the inside walls of the pool, spa, or hot tub.
(e) Bonding. Shall comply with 600-7.
Subsection (e) informs us that the bonding shall comply with Article 600, Electric Signs and Outline Lighting; Section 600-7, Grounding.
(f) Grounding. Any equipment associated with the sign shall be grounded as per Article 250.
Subsection (f) informs us that any equipment associated with the sign installed in a fountain shall be grounded as per Article 250, Grounding.
Read more by Robert Milatovich
Posted By Craig B. Toepfer,
Monday, March 01, 1999
Updated: Monday, August 27, 2012
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When smog kept suffocating three sprawling cities—Los Angeles, Paris, and Tokyo—in the early 1990s, a standardized infrastructure for charging electric vehicles (Evs) was at last seen as a worthwhile goal. The superiority of clean Evs to dirty gas-powered transportation was borne in on everyone as never before. But Evs stood no chance of success without a refueling infrastructure that matched the corner gas pump for availability and ease of use. The ultimate in convenience would be an infrastructure that let Evs charge up at home.
In France, the government in concert with the national electric utility, Electricite de France, and the domestic auto manufacturers, began an aggressive EV test and development program. In Japan, the Eco-Station demonstration project was established by the Japan Electric Vehicle Association (JEVA). JEVA had been established by the Ministry of International Trade and Industry in 1976 to coordinate EV development among government, universities, research laboratories, and the auto industry. The Eco-Station project offered environmentally friendly vehicles—electric, natural gas, methanol, and others—a familiar gas-station refueling environment. Part of this project resulted in a proposed connector configuration and plans for "fast” charging an EV, that is, charging at least 50 percent of the battery in 15 minutes of less.
Figure 1. The International Electrotechnical Commission (IEC) denotes them by two-letter designations as follows: T-N, T-T, and I-T
In the United States, two events jumpstarted the domestic EV industry—the push in 1990 by the California Air Resources Board for EV mandates to take effect as early as 1998, and the bold declaration by General Motors Corporation, Detroit, at the 1991 North American Auto Show to be the first to market with an EV. In response, the Electric Power Research Institute (EPRI), Palo Alto, California, organized the Infrastructure Working Council (IWC) in 1991 to rally experts from the electric utility, automobile, and electrical equipment industries to address the issues of EV infrastructure for battery charging—charging system architecture, couplers, and technical and societal impacts.
Every major new technology from radio to TV (black and white, color, and high-definition) and VCRs, from computers to Evs relies on basic technical standards to make the transition from invention to commercial success. In the early 1990s, the groundwork for an EV industry was laid by a carefully coordinated international effort to establish a common means of charging EVs and to develop standards to ease their commercialization.
Figure 2. They rely variously on an isolated supply, an isolated charger, or a nonisolated charge
The experts worked in various forums to understand the challenges, set boundary conditions, and negotiate the standards development process. The result has been the timely creation of standards, so that Evs may be produced and sold just as the auto industry is moving from demonstration and development to production.
Starting from Scratch
A standard electrical charging connection is analogous to the familiar gas pump nozzle, but it presented unique challenges to these experts. After all, spilling a few drops of gasoline at the pump is not inherently dangerous to the klutz, but spilling a few coulombs onto the human body is. Unlike duel, which must be vaporized or ignited to create a hazardous condition, electric power flows in an energized state that must be handled carefully.
In fact, connecting an EV to the electrical network for charging presents an unprecedented set of conditions. For the first time in history, consumers, members of the general public of all ages, would be asked to make a high-power electrical connection—typically between 5 and 150kW—perhaps once or twice a day, and outdoors in all types of weather.
Consumer safety was of the essence. Thus, the top priority requirements of a standard EV charging system and associated "”plug”" were that it first and foremost be not only safe, but perceived as safe; that it be intuitive and easy for consumers to use; and that it be cost-effective. Ideally, too, a standard charge coupler between the vehicle and power source would be compatible with electric networks around the world.
Figure 3. The three available methods are cord with a plug end, cored with a connector end, and cord set
This set of conditions mandated a double-fault safety management system to circumvent or mitigate potential shock hazards from the standard EV charging system. In other words, a consumer would still be protected while connecting the vehicle to the power source despite one or even two failures in the safety system.
Classical electrical safety management techniques, which serve as the basis for electrical safety standards around the world, require the systematic layering of basic (insulation), fault (fuse), and additional (ground-fault circuit interrupters) protective measures. The exact measures used vary with the nature of the product involved (in this case, electric-vehicle chargers); its electrical characteristics (voltage, current, frequency, and network configuration), type of user (general public or qualified persons); and conditions of use. The perception of safety is slightly less well defined, but most would grant that seeing exposed conductive elements could discomfit the casual user, and touching them could be even more upsetting.
Standard household and industrial wiring devices prompted the criterion that the plug be easy for consumers to use. However, the electrical connectors under consideration were not. Instead, they were very large and heavy to accommodate the power levels under consideration, required a certain orientation for proper use, and needed significant insertion force. To compound matters, most standardized wiring devices had not been designed for high-durability applications where the connection must be made as often as daily (possibly more frequently) and in all types of weather.
Figure 4. The system architecture basically consists of a high-frequency converter connected to the power supply off-board the vehicle, a high frequency take-apart transformer at the vehicle interface, and an on-board rectifier and charge controller
The cost impact of the EV charging infrastructure on vehicle, electric utility, consumer, and society had to be carefully considered. In the absence of an installation designed for the purpose, the relative costs could only be evaluated by establishing a basic charging system architecture—location of charging apparatus, inlet, and charging control, and the speed and size of the charger. In turn, this would drive the allocation of cost between the vehicle and the supply network and determine the interface or coupler cost.
In an ideal world, a single coupler design would be developed that was compatible with the different electrical characteristics of networks used in every country. Over and above their well-known differences in voltage and frequency, these networks have three basic configurations. The International Electrotechnical Commission (IEC) denotes them by two-letter designations as follows: T-N, T-T, and I-T [Fig.1}.
The first letter, T or I, describes the relationship of the system to earth. T, for terra or earth, indicates that the system is earthed or grounded and this is by far the most widely used network. The I designation indicates that the system is isolated from earth or in some cases connected to earth by a controlled impedance.
The second letter designation identifies the relationship of exposed conductive parts (the prongs on a plug or the slots on the receptacle—for example, to the installation of earth. In this case, T signifies that the utilization equipment is directly earthed independent of the system earth and N, neutre or neutral, signifies that the protective earth of the utilization equipment is connected to or common with the system earthing conductor.
The T-N system is the most popular and can be found in North Central, and South America, many areas in Europe, most of Asia, Australia, and much of Africa. The T-T system is used primarily in France, Southern Europe, and Northern Africa.
In developing an appropriate EV charging infrastructure, a system-level approach had to consider all aspects—the generation, transmission, and distribution of electricity, the wiring systems in homes, commercial buildings, and industrial facilities, the special equipment for charging, and the EV.
A tremendous advantage of EVs is that they are the ultimate alternative fuel vehicles. They shift reliance from a single fuel—gasoline—to the broad range of primary feedstock used for electric power generation—coal, natural gas, oil, nuclear, hydro, and renewables. Subsequently, an improvement is electric-utilityi generation efficiency can be realized by charging EVs during periods of low (off-peak) demand—overnight. This allows increased use of larger more efficient baseload generating facilities.
The exploitation of off-peak capacity establishes the first boundary condition for EV charging—that the charge process take no longer than 8 to 10 hours. Simple mathematics provides nominal charging requirements. Representative values, such as 4 5-8 km/kWh and a desired customer driving range of 160-240 km. yield battery capacities around the 20-50-kWh range and charge rates of 3-9kW, or 6kW nominal, when charger and battery charge efficiencies are factored in.
Figure 5. The conductive ac/dc-coupled system is based on a standard coupler interface and an open system architecture that supports the use of either on-or off-board charges, all of the three possible connection schemes, and voltage, current, and voltage
In North America, where 240-V single-phase is the most common electrical supply, this yields a 30-A circuit, on a par with an electric clothes dryer. That value is well within reach of the transmission, distribution, and installed-service capabilities in use everywhere. This is particularly true when charging overnight, when electricity usage is lowest and most economical, is considered. In a nutshell, the compatibility of EV charging with the existing network neatly sidesteps the costs of upgrading transmission, distribution, and electrical services.
The next step in establishing standards is to set boundary conditions for the EV charging system architecture. A battery charger in essence performs two basic functions: it converts alternating into direct current, and it regulates the voltage in a manner consistent with he ability of a battery to accept current. There are three recognized methods of connecting a battery to the network through a charger. They rely variously on an isolated supply, an isolated charger, or a nonisolated charger [Fig. 2]. All of these methods have unique merits and should be accommodated in a general architecture scheme.
Plugging in, Turning on
A second key consideration in EV charging is the vehicle’s physical connection to the supply network. The three available methods are cord with a plug end, cored with a connector end, and cord set [Fig. 3]. The most popular and familiar methods of connecting equipment is to attach a cord and plug to the appliance and connect to a receptacle or electrical outlet. (Typically, plugs have prongs that fit into a receptacle; connectors do not.)
This works fine with stationary devices that are connected and generally left alone such as a lamp, range, dryer, stereo, TV, and so on. It works less well for EVs where daily or more frequent connection in all weather conditions and safely managing and storing a large cord on the vehicle, especially for high-power fast charging, becomes technically unreasonable and a potential consumer inconvenience.
Because a dedicated circuit with special equipment will probably have to be installed to charge an EV, the auto manufacturers unanimously agreed that the familiar gasoline pump configuration where the hose (cord) and nozzle (plug or connector) are fixed to the pump (charging equipment) is the preferred method. This solution combines convenience with flexibility in coping with special conditions, such as long distances between charging equipment and the vehicle inlet. The third methods of using a cord set fitted with a plug and connector was considered as acceptable for limited situations such as charging from a common existing receptacle.
Given the above scenario where equipment operating at 200V in Japan, 230V in Europe, and 240V in the United States and 40 A nominal, is the preferred and most popular method of EV charging-—known as Level 2 charging—two other methods that address EV customer concerns were also considered. From the start, customers had been worried about the charge time and access to charging facilities. To reassure them, what have come to be known as Level 3 and Level 1 charging were established.
Level 3 or fast charging replenishes more than half of the battery capacity in approximately 10-15 minutes at a commercial public facility. Note that the IWC set the levels and their basic criteria. Level 3 charging is particularly suited to fleet applications where a 15-minute opportunistic charge during a lunch break can significantly extend a vehicle’s daily range and use.
Level 1 charging allows a vehicle to access the most popular grounded standard outlet. Since most garages in the United States have a 120-V/15-A duplex outlet, and similar receptacles abound in other countries, being able to hook up for EV charging is handled by an adapter cord set (a cord with one plug end and one connector end). However, the limited power capability of this outlet and regulations governing circuit sharing and continuous loads (steady demand for 3 hours or more) restrict Level 1 charging to emergency or limited convenience use in North America.
The long-term vision of EV charging includes a mix of facilities. The highest-priority charging points are points of access at home and workplace. Public access charging at such facilities as malls, airports, and park and ride mass transit stations compliments these primary points. Commercial, public fast-charge stations further encourage EV use by solving range limitations and consumer concerns over long charge times.
A standard connector or plug for charging must support the basic charging system architecture. Whatever the charging system configuration and battery type or size, and regardless of customers’ conviction that it is the auto makers’ job to service the battery, the auto makes concurred that control of the charge process would reside on the vehicle—regardless of where the charger is located—to optimize the performance of the battery. Subsequently, two coupler technologies, inductive and conductive, have been the focus of technical and standards development.
The great debate: inductive…
Shortly after announcing its intention to be the first to market with an EV, General Motors indicated it would be using a unique inductive coupler technology for connecting its vehicle to the network for charging. The core element is based on the concept of a take-apart transformer. The system architecture basically consists of a high-frequency converter connected to the power supply off-board the vehicle, a high frequency take-apart transformer at the vehicle interface, and an on-board rectifier and charge controller [Fig.4].
The system is fundamentally an isolated-charge type with the off-board power electronics serving as a current source as commanded by the on-board charge controller. In regulating charge rate, the charge controller communicates with the frequency converter over a close-cooupled radio-frequency media link using a standard J1850 Class B Data Communications Network Interface and the recently developed J2293 protocol for EV charging, both from the Society of Automotive Engineers (SAE).
Increasing the frequency from the line to the 100-kHz-plus range reduces the size of the plug to allow ease of use for the consumer. Functionality and interoperability are ensured by strict control of both the off- and on-board equipment, yielding a system standard as opposed to just a coupler standard.
The inductive system is presently being used with the GM EV1 and Nissan Altra EV. High-power versions, up to 120kW, have been demonstrated. A second generation of the inductive system is currently being jointly developed by GM and Toyota Motor Corporation, Tokyo.
Other auto manufacturers opted to develop a more traditional approach based on simple contact technology. The conductive ac/dc-coupled system is based on a standard coupler interface and an open system architecture that supports the use of either on-or off-board charges, all of the three possible connection schemes, and voltage, current, and voltage/current source chargers [Fig. 5].
For primary Level 2 charging, most OEMs prefer an on-board charger where ac power is supplied to the vehicle over an intelligent switch, and the network protective earth is connected to the vehicle chassis during charging. In these circumstance, the charger design can be optimized for the vehicle and the infrastructure costs can be minimized to include only the contactor, enclosure, and supervisory electronics to ensure safe operation.
For Level 3 fast charging, the size and weight of the charger mandated that it be an off-board device, with dc power being transferred to the vehicle. But the system also accepts lower-rate off-board chargers. In this case, hardwire communication media is used by the vehicle controller to regulate charging using the same SAE J1850 and J2293 standards as the inductive system.
The interface to support an ac/dc conductive coupled system [Fig. 5 again] is a nine-pin configuration for North America consisting of:
- Two single-phase ac contacts rated 240V ac 60 A, and 14.4 kVA.
- Two dc contacts rated 600 V dc, 400A, and 240 kW.
- One equipment ground, sized for fault clearing.
- One control pilot signal contact for the control, interlock, ground monitoring, and ampacity marking functions.
- Three signal contacts for the hardwire communication media.
The mated coupler components, connector, and vehicle inlet can be populated with whatever power and communication contacts are required by the supply equipment or vehicle. The equipment ground and control pilot contacts are always required.
The coupler design uses a butt-type contact and is derived from the product developed for the EV test and demonstration program in France. This design was selected by SAE after extensive durability testing of the basic contacts and the prototype components. With this design, the contacts are shielded on the connector and inlet when disconnected. During the insertion and rotation involved in connection, the shields are automatically retracted. This method of connection and type of contact produced a design that was easy to use, even when configured for high-power dc transfer, and provided an additional safety measure.
Setting the standard
The recommendations of the EPRI-IWC Connector and Connecting Station Committee were published in December 1993, and codes and standards development for charging equipment proceeded apace through the next few years. In the United States, under the auspices of the EPRI-IWC Health and Safety Committee, a panel of experts was convened to develop an article (standard) on EV charging equipment for the 1996 National Electrical Code® (NEC). The proposed revisions were to include Article 625, Electric Vehicle Charging System Equipment. The result was approved for publication in the 1996 NEC and has been updated for the 1999 NEC. Also during this period, the SAE EV Charging Systems Committee developed and approved SAE Recommended Practices for conductive (J1772) and inductive (J1772) charging systems.
Development of a consensus on product standards was initiated by Underwriters Laboratories Inc., in step with activities of the SAE and NEC. Presently, outlines of investigations are under way to establish three EV-related product standards. They are UL 2202, UL 2231, and UL 2251. UL 2202 is the proposed standard for EV charging equipment and covers all nonvehicle electrical equipment for EV charging. UL 2231 is the proposed standard for personnel protection systems for EV supply circuits and covers the requirements for a layered system of double-fault protection for both grounded and isolated charging system. UL 2251 is the proposed product standard for plugs, receptacles, and couplers for EVs.
Incidentally, UL 2231 came out of a comprehensive UL study funded by EPRI, Ford, GM, and Chrysler on personnel protection. Although it presently applies to EV charging systems, it is suitable for general electrical equipment and may be more broadly applied in the future.
With the selection of two charging technologies, conductive and inductive, and their means of coupling, codes and standards are in place or in development in the United States to support EV commercialization. Similar efforts are ongoing in Canada and Japan, and within the IEC.
Canada has revised Part I of its electrical code by adopting Section 86 for EV charging systems and is starting on Part 2, product standards, this year. These standards are or will be closely harmonized with their U.S. equivalents.
The Japan Electric Vehicle Association has published four standards governing conductive EV charging equipment, which from a system architecture standpoint, are closely akin to the U.S. and Canadian standards. An exception is the connecting means, which presently uses the product developed for the Eco-Station project described earlier.
As for the IEC’s Technical Committee 69 for Electric Road Vehicles, its Working Group 4 for charging infrastructure is close to circulating a committee draft for voting. This document has received active input from representatives of the automotive industry around the world and is also harmonized to the extent possible with North American and Japanese activities. If approved, this document will set the requirements for the European community and other IEC member countries.
As the year 2000 approaches, EVs are rapidly moving from demonstration to volume production, thanks in large part to the technical community. In cooperation with standards development bodies, it has delivered a strong foundation for a safe, efficient, and high-value EV charging infrastructure that addresses the complexities of the supply network and vehicle interface with a harmonized solution. Only one question remains: will conductive or inductive charge-couplers prevail in the long-term marketplace?
Copyright © 1998 by November IEEE. Reprinted, with permission fromIEEE Spectrum Magazine, pgs. 41-47. Reprinted with permission.
Read more by Craig B. Toepfer
Posted By NEMA ,
Monday, March 01, 1999
Updated: Monday, August 27, 2012
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The National Electrical Manufacturers Association has just what you need to answer your circuitbreaker application and preventive maintenance questions. NEMA publishes two standards that provide a wealth of information to help users and specifiers select and maintain circuit breakers.
NEMA Standards Publications AB 3-1996 and AB 4-1996 can answer application questions and preventive maintenance questions for molded case circuit breakers. Proper use of these standards can help prevent fire and shock hazards, down-time due to systems failures, and other operations mishaps.
The two NEMA standards serve a different purpose than the standards used to certify circuit breakers. Molded case circuit breaker manufacturers in the US certify their products to the safety and performance requirements defined in the Underwriters Laboratories Inc. UL 489 standard. When circuit breakers meet or exceed these requirements UL permits their listing Mark to be placed on the circuit breaker. Electrical inspectors that enforce electrical codes look for this listing Mark when approving electrical installations.
While knowledge of the construction and performance requirements is important to manufacturers, information regarding the application, field testing, and maintenance of circuit breakers is more important to specifying engineers, installers, and maintenance personnel. That information is found in these two NEMA standards.
If you specify molded case breakers:
The NEMA AB3-1996 standards publication, Molded Case Circuit Breakers and Their Application, describes the types of circuit breakers available and many of their specific applications. It also lists circuit breaker accessories and ratings, and provides guidance on the selection of circuit breakers. Finally it defines much of the terminology associated with circuit breaker products. In addition to molded case circuit breakers, NEMA AB3 covers molded case switches and their accessories.
Section 5 of NEMA AB3 is especially useful for those who select circuit breakers. This section covers the following topics:
- electrical system parameters environmental conditions (extreme temperatures, humidity, corrosive atmospheres)
- feeder and branch circuit breakers
- load considerations
- temperature ratings of conductors and conductor ampacity
Section 5 also includes a detailed explanation on the following:
- time-current curves
- series-combination ratings
- capacitor switching considerations
- motor loads
- ground-fault protection
- circuit breakers used in DC voltage systems
Finally, Section 5 provides a basic overview of the UL standards requirements for the Listing of circuit breakers.
If you inspect or maintain molded case breakers:
The NEMA AB4 standards publication, Guidelines for Inspection and Preventive Maintenance of Molded Case Circuit Breakers used in Commercial and Industrial Applications, provides guidance for maintenance and field testing of circuit breakers and explains how to evaluate the condition of a circuit breaker. NEMA AB4 provides basic procedures that may be used to inspect and maintain molded case circuit breakers rated up to and including 1000 volts, 50/60 Hz ac or ac/dc. The test methods described in NEMA AB4 may be used to verify certain characteristics of circuit breakers originally built and tested to the requirements of the UL 489 and NEMA AB1 standards. However, it is not intended, nor is it adequate, to verify proper electrical performance of a molded case circuit breaker which has been disassembled, modified, rebuilt, refurbished, or handled in any manner not intended or authorized by the original manufacturer.
These test methods are intended for field use only and are non-destructive. They cannot be used to verify all performance capabilities of a molded case circuit breaker, since verification of certain capabilities requires destructive testing.
Some industrial users have indicated that they are required to conduct periodic operational tests of their circuit breakers. The non-destructive tests outlined in Section 5 of NEMA AB4 may be used to verify certain operational characteristics of molded case circuit breakers including:
- mechanical operation
- insulation resistance
- individual-pole resistance
- inverse-time overcurrent tripping
- instantaneous overcurrent tripping
- rated hold-in current
Section 6 describes tests for the proper use of devices such as shunt trip and undervoltage trip releases, electrical operators that allow opening and closing the circuit breaker from a remote location, auxiliary switches that operate when the circuit breaker opens or closes, and alarm switches that operate when the circuit breaker trips automatically.
The NEMA AB3 and NEMA AB4 standards publications are valuable tools for the safe and efficient operation of molded case circuit breakers. They are indispensable to contractors, specifiers, plant engineers, and maintenance personnel. Keep these NEMA standards in mind the next time you have an application or maintenance question concerning molded case circuit breakers. For a copy of AB3 or AB4 call NEMA at 703/841-3201 or IHS at 800/854-7179.
About NEMA: NEMA is the trade association of choice for the electrical manufacturing industry. Founded in 1926 and headquartered near Washington, D.C., its approximately 450 member companies manufacture products used in the generation, transmission and distribution, control, and end-use of electricity.
Posted By Arthur "Bud" Botham,
Monday, March 01, 1999
Updated: Monday, August 27, 2012
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Imagine yourself with the responsibility to provide more than 50,000 amps of safe electrical power over 140 miles of distribution cable powering 5,000 lighting units, day and night, for over seven months.
Now add the following: 3,000 "practical” units will be repeatedly submerged in sea water, and, if that’s not enough, hundreds of swimmers will be in close proximity to these submerged sources while fully energized.
This was the reality set before the production crew as they embarked upon the creation of the most complex motion picture in history—Titanic.
Photo 1. The components that make up the advanced ground-fault current interrupter (GFCI) include a 40-amp single phase, 400-amp GFCI-RCMA service, and the panel mount GFCI. On the left is the panel mount 40/60-amp single or 3-phase, center is the 400-amp
Here is the story about a safety problem as old as harnessed electrical power itself … and about a new solution which was found and successfully executed (without executing anybody).
Back in 1986, camera operator Bill Masten and electrician Rick Prey formed a company, SMS Inc., with the slogan, "The Quiet Mobile Generator Company.” Primarily known for their award-winning NiteSun products—portable generator trucks which boomed 12k HMIs to heights of 120 ft—these two had provided necessary equipment to the production world for over a decade.
When Prey, a Navy trained electrician, worked on The Abyss, they used the electrical equipment that was available at the time, .and it scared us to death,. says Prey. He had worked on several shows involving water, and found that the equipment they needed wasn’t available. They could buy the appliances, but found that .we had protection, but not personnel protection.”
On his next assignment, Crimson Tide, Prey and gaffer Dwight Campbell realized that the equipment was still insufficient. Prey and Masten had been tinkering with ideas, and had come closer with modular devices from the Bender Corporation, when Campbell started working on Hard Rain. But the problem wasn’t solved. .It still wouldn’t pass UL standards. No standards even existed for three-phase GFCIs,” says Masten.
Prey and Masten decided to tinker away at a prototype. With sketches in hand, they went to Bender Engineering with their ideas.
Photo 2. The components that make up the advanced ground-fault current interrupter (GFCI) include a 40-amp single phase, 400-amp GFCI-RCMA service, and the panel mount. (Left to right): 3-phase GFCI for chainmotors; 200-amp GFCI single or 3-phase; 100-amp
PowerGuard is the most advanced single and three-phase Ground Fault Circuit Interrupter (GFCI) personnel protection device in the world and the only three-phase GFCI currently UL listed for personnel protection. Before Titanic it didn’t exist. Here’s how it happened.
For Masten and Prey, "Titanic was a call we had been waiting for. Cinematographer Russ Carpenter, gaffer John Buckley and rigging gaffer Mike Amorelli had less than two weeks to find a 1200-amp GFCI that would work and wouldn’t cause false tripping … nothing was available,” says Masten.
Amorelli emphasizes that, "safety was the most significant aspect of our planning for the picture. The scope of the production alone made this a fact of life. In addition to safety, director Jim Cameron wanted the highest level of reality. That meant literally hundreds of people in, around and under the water, with hundreds of lighting units. Knowing all of this, we made safety the number one concern for all of us.”
"John and Mike had to thread the eye of the needle on Titanic in regard to electrical safety,” explains Carpenter. "Because of the complexity of many of the sets, John’s crews were rigging some stages weeks before the first unit got to them. John and his team had to ascertain how to route power into sets that moved, submerged, or in some cases, literally broke apart. He had to consult with the production designer, mechanical effects supervisor, the director and those persons in charge of water distribution in order to determine what would, in even the wildest scenario, become wet or immersed. Amorelli explains that, "To meet Russ and John’s lighting requirements, we needed a combination of HMIs, incandescents, dimmers and ‘specialized’ lighting units. John and I knew that DC power would not accommodate all of our needs. Traditional methods for handling AC around water were insufficient for a project on the scale of Titanic (50,000 amps were needed for the ship alone). We needed a 1200-amp GFI.”
Photo 3. Captains of their ship: Bill Masten (left) and Rick Prey (right) in front of their NiteSun truck
Masten and Prey figured that with Bender Corporation’s efforts on the Magnetic Levitation Train, "we had a lead,” says Prey. They thought that some of the technology could be applied to their prototype. Marcel Tremblay of Bender agreed to study their schematic. Joe Boardman, then Chris Bender in Germany, and their German lab became involved. Gary Glick at Siemens provided lab time and prototypes.
Buckley recalls that "safety was paramount throughout Titanic. Cameron insisted, and we all agreed, we couldn’t do this film without absolute safety. Approximately 350 people would be in the water. AC power was the only real choice to accomplish the task, and, of course, that had never been done on the scale with which we were dealing. Remember, the greatest amount of lighting equipment ever assembled was also subjected to the elements for over seven months. Right from the beginning, I knew that we needed fault protection devices capable of protecting circuits of twelve hundred amps. Just over two weeks before we started, nothing of that kind existed. We had to have them … period! Some people said, ‘You’re crazy to even try it.’ We turned to SMS because I knew Rick Prey and Bill Masten had built a lot of equipment. Rick listened to our .problem. and agreed to ‘try it.’”
Adds Carpenter, "On the one hand, they had to create a device which avoided serious injury to people in the water and yet wouldn’t be false tripping all the time, costing expensive down time while we waited for the systems to be reset. That dictum translated into serious research, development and testing of the new GFI systems by our team and the folks at SMS.”
Explains Joe Boardman, Bender Engineering, "Rick Prey called and told us about Titanic. We listened to the rather amazing set of problems the film would confront. The magnitude of power needed was beyond the scope of the ‘standards’ for any existing GFCIs and the harsh environment was another factor. We learned that the movie industry in general offers a singular mode of operation. It uses a wide range of voltages which often change. It combines all the facets of a large industrial site, yet it’s a highly mobile endeavor. As one crew member put it … ‘It’s like the circus without the elephants…’”
"After days of calls to countless electrical engineers,” explains Amorelli, "we concluded that while the theory was sound, no one had ever built a GFI of that size.” After we contacted SMS, "Rick and Bill tackled the problem.”
In short order, the prototype arrived in Mexico. Amorelli recalls that "after changes were made, testing was completed and we had the first ever 1200-amp GFI in the business. All totaled, SMS built twenty-eight 1200-amp GFIs, a number of 100-amp 120-volt and 100-amp 240-volt models. The PowerGuards allowed us to safely operate the most complex lighting scheme I’ve ever encountered and on the grandest scale ever attempted.”
Buckley explains that without ever "losing sight of all those cast and crew members we would have in the water when thousands of lights were sunk with the ship, we began to test. This was an anxious period for us. But it worked! I knew we could safely light Titanic in spite of the wet environment. Once, a high wind dragged a piece of heavy duty lighting equipment into the water. The PowerGuard system shut down instantly. We used over twenty of the 1200-amp units on the show. I know that they saved lives.”
Bender Corporation’s Marcel Tremblay explains their involvement. "We felt that here was a unique opportunity to work together with SMS on solutions. However, there was a limited time frame. With a sketch of the electrical distribution layout from Rick and a lot of cooperative effort between us, we developed a prototype. But it had to comply with existing and developing standards. If its sensitivity were too great, it would be tripping all the time. The goal was to have a device that could sense minute currents at the ‘let-go’ level and that would incorporate features such as an inverse time curve to prevent false tripping when used in circuits rated as high as 400 amperes. This meant literally expanding the technology envelope. The standards didn’t even mention three-phase power for personnel protection.”
The founders of SMS were just 80% "there” when the call came from Titanic. Masten explains, "Mike told us we would have 50,000 amps in water with people, in two weeks. We said, ‘We’ll try.’ The race was on for a working prototype. We had amazing help from Bender, Siemens and the Titanic crew to close the gap.”
Pressure? The prototype took eighteen months. As Titanic shoved off, PowerGuard was, at last, a reality.
Not long after the field test results were in, Bender Corporation’s staff worked out some changes until they had a unit that would provide the highest level of "people protection” ever. The system worked. Recently it has received the UL listing for personnel protection.
Adds Tremblay, "We look to the future now with the knowledge that this breakthrough will improve safety throughout the industry. New products already at hand allow the crew to check the condition of the entire electrical setup even before it is even energized.”
Necessity is most often credited for new inventions. It is ironic that RMS Titanic was credited with bring many life-saving inventions to sea travel and the world, following her tragic end. Luckily, nobody had to die on a film shoot in order to necessitate the invention of the PowerGuard.
It has been said, "Most things we will use in our daily lives, just ten years from now, have not yet been invented.” The film Titanic gave birth to a life-saving device, the PowerGuard.
Amorelli notes, "Technical breakthroughs made on this film will give directors new avenues to achieve the heightened sense of reality and greater production values demanded by today’s sophisticated audiences. I am proud to have been a part of a project where technological advances, such as the development of the 1200-amp GFI, were conceived and realized.”
What’s next for Rick Prey and Bill Masten? Currently, they are refining the equipment, and have also branched out into insulation detection for leaking equipment. This insulation detection device was recently used in the Bellagio Hotel in Las Vegas. As for the GFCI, having generated such success on Titanic, it has moved on to other features. Its list of credits reads like a seasoned veteran: Godzilla, Sphere, The Negotiator, Virus, Mafia, and EDtv.
As the Bender Engineering team said, "We are proud that PowerGuard gave those who made this wonderful film (Titanic) a safer workplace.”
For Bill Masten and Rick Prey, they agree that "Titanic has made history and made all of us who were part of its creation a part of that history … who can ask for more than that?”
Read more by Arthur "Bud" Botham
Posted By Robert Duncan,
Monday, March 01, 1999
Updated: Monday, August 27, 2012
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Article 695 first appeared in the 1996 National Electrical Code, it covers the electrical construction and installation portion for Fire Pumps. The performance, maintenance and testing requirements are in NFPA 20.
The committee received 23 proposals during the proposal stage and received 34 public comments during the comment period.
In Article 695 portions are marked with a superscript "”x”" which means it is extracted material from NFPA 20, Standard for the Installation of Centrifugal Fire Pumps. This reflects the work of both CMP 15 and NFPA 20 which has been supported by a joint task group of members of both committees which has been very helpful in providing a good working arrangement with both groups.
The following are some of the significant changes that appear in Article 695 of the 1999 NEC.
Section 695-3 has probably had the most significant changes. The power sources for Electric Motor-Driver Fire Pumps must be reliable and capable of carrying the sum of the locked-rotor current of the hre pump motor (s) and the pressure monitor pump motor(s) and the full-load current of any hre pump accessory equipment when connected to this power sources. Power sources may be one of three types.
- A separate utility service.
- On-site power production facility.3. Multiple Sources, which are a combination of a generator, Separate service or feeder source, when approved by the authority having iurisdiction.
Section 695-3(b)(2) was added to the 1999 NEC to cover independent feeders serving multiple buildings. This section requires the supply conductors to comply with Section 695-4(b).
Section 695-6 was revised to eliminate some exceptions and to clarify the requirements. 695-6~ address the conductor sizing is based on 125 percent of the fire pump motor and 100 percent of any associated fire pump accessory equipment and not based on the locked rotor current of the fire pump.
Section 695-6(e) now permits the use of Flexible nonmetallic conduct Type LFNC-B as a wiring method for pumps.
Section 695-6(fl reflects that the UL listing requires that no other loads, other than the fire pump motor are to be connected to the fire pump power transfer switch.
Section 695-7 was added to clarify that voltage drop is from the power source and not the power wiring.
Section 695-10 requires the Fire Pump Controller, Transfer Switches and Motors are required to be listed for fire pump service. This requirement has been in NFPA 20 and is not included in Article 695. UL currently has companies that have their equipment listed.
About Robert Duncan: Robert C. (Bob) Duncan, IAEI Representative CMP-15, has been a member of CMP-15 since 1987. Member NFPA 20, Fire Pumps Member NFPA 96, Ventilation Control and Fire Protection of Commercial Cooking Operations. Member ASME A17.1 Safety Code for Elevators and Escalators, Electrical Committee Member NFPA, Past IAEI Chairman Southern Section, Florida Chapter and Central Florida Division.
Posted By Leslie Stoch,
Monday, March 01, 1999
Updated: Monday, August 27, 2012
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Sections 18 and 20 of the Canadian Electrical Code define hazardous locations and specify the types of electrical equipment and wiring methods acceptable in areas where flammable or explosive materials are handled, stored or produced. In such areas, the risk of a fire or explosion may exist due to the presence of flammable gases or vapours. The electrical code provides requirements for protection in hazardous locations, from electrical ignition sources, due to the effects of electrical arcing or heating.
Sections 18 and 20 have always seemed rather complicated to the average person. Now they may seem even more so, since we have just inherited two different methods for classifying Class I hazardous locations and methods of protection for each. As you begin to peruse the 1998 Canadian Electrical Code, Sections 18 and 20, you will notice some major changes. Class I locations are now defined as "explosive gas atmospheres,” which contain "a mixture with air, under atmospheric conditions, of flammable substances in the form of gas, vapour or mist–”. In other words, if a flammable or explosive gas, vapour or mist can occur, the area must be classified.
You will also discover that the two-division system has been replaced by three zones. At the beginning, I should point out that both systems result in a safe installation when equipment and wiring are correctly installed. In this article, let’s review the differences and similarities between the old system of classification and the new.
In the 1994 CEC version, Class I hazardous locations had two divisions:
Division 1– where flammable gases or vapours exist:
- Continuously, intermittently or periodically
- Due to repair, maintenance or leakage
- Due to breakdown or faulty operation
Division 2– where flammable gases or vapours:
- Are in closed systems or containers
- Where prevented by positive mechanical ventilation
- Next to a Division 1 location, with positive air pressure
In the 1998 CEC, the 1994 requirements have been moved to Appendix J, and the earlier requirements have been replaced by the new IEC system in Sections 18 and 20.
In the new 1998 CEC, Class I hazardous locations are divided into three zones in accordance with the European IEC classification system, which recognizes a higher hazard level than we are accustomed to in North America:
Zone 0– where an explosive gas atmosphere exists continually or for long periods. It is estimated that such locations are found in only 1% of hazardous location installations. Under our Division system, Zone 0 would have fallen within Division 1, but with no special recognition of a higher hazard level.
Zone 1- where an explosive gas atmosphere:
- Is likely to occur in normal operation
- May exist due to repair, maintenance or leakage
- Is next to a Zone 1 location
Zone 2– where an explosive gas atmosphere:
- Is unlikely, but may occur for a short time
- Flammable materials may be handled, stored, used or contained in a closed system
- Next to a Zone 1 location with positive air pressure
You may have noticed that the definitions for Zones 1 and 2 are almost identical to our old Divisions 1 and 2. The big change is Zone 0, which is intended to contain the most hazardous conditions.
In the 1998 CEC, the Scope paragraph of Section 18 prescribes application of the new zone classification system as follows:
- The Division system of classification may still be used for additions, modifications and renovations to existing facilities
- Appendix J requirements are to be followed when classifications are made in accordance with the Division system
- Class I, Zone 2 electrical equipment may also be installed in a Class I, Division 2 hazardous location
Eventually, you may find that the provincial and territorial electrical code authorities may still decide to amend the application of the new system of classification.
Where the old system required the use of explosion-proof electrical equipment, the new system permits a wider assortment of equipment types, all of which can satisfy code requirements when correctly applied.
Zone ILocations – may have equipment of the following types:
- Class I, Division 1
- Intrinsically safe – creates insufficient energy to ignite a fire or explosion
- Flameproof – similar to explosion-proof
- Increased safety – a method of ensuring connections don’t come loose, causing sparking or overheating
- Pressurized – using a protective gas
- Encapsulated – arcing contacts are enclosed within a com pound
Zone 2locations – may have equipment of the following types:
- Class I, Division 1 or 2
- Intrinsically safe
- Equipment permitted in Zone 1
- Nonincendive – a form of intrinsic safety, but only incapable of causing an ignition under normal conditions
- No-arcing, sparking or heat- producing
In some cases, electrical equipment may use more than one of the above protection methods.
You may also have noted that wiring methods for Zones 1 and 2 are quite similar to Divisions 1 and 2, except that:
- Non-tapered threads are acceptable, but in some atmospheric groups, must have at least eight engaged threads
- Adaptors must be used where wiring systems and equipment have different threadforms
- Some equipment has factory- made seals and does not require field-installed seals
Only intrinsically safe electrical equipment marked ExI or Exia is permitted in Zone 0. Intrinsically safe circuits are usually instrument wiring to sensors in the Zone 0 hazardous locations. An example of a Zone 0 location is within the nozzle boot of a gasoline dispenser.
Intrinsically safe electrical equipment does not require a flame-proof enclosure, field-installed sealing or any other protection method. However, field-installed seals are required at:
- The point where conduit leaves a Zone 0 location
- The first termination after a cable enters the Zone 0 location.
All flammable gases and vapours are grouped according to their common explosive characteristics. Under the North American system, four levels are used – A, B, C and D. The IEC system uses three levels – IIA, IIB and IIC. Both designation systems are found in the 1998 CEC. In the IEC system, electrical equipment temperature codes are reduced from fourteen to six.
As in past articles, your local inspection authority should be consulted for a precise interpretation of any of the above in each province or territory as applicable.
Read more by Leslie Stoch