very year they are involved in accidents
that kill thirty people and seriously injure seventeen
thousand.1 Before you let
that statistic scare you into using another route, remember
that you are fifty times more likely to get hurt taking the
stairs. Also, half of these deaths involve people who are
working on elevators.2 Falls
or being caught by the moving parts of elevators causes most
of these deaths. Article 620 of the National Electrical
Code has evolved through the years in an effort to prevent
these injuries.
NEC-2005
Changes
Changes to Article 620 were fairly simple. You are now
prohibited from installing the elevator lighting on the load
side of a ground-fault circuit interrupter. Motor overload
protection must conform to Part III of Article 430, in
addition to the requirements of 620. Overload protection using
430.33 is optional now. Definitions of control room, control
space, machine room and machinery space were
added in 620.2 (see
figure 1).
Separate Branch
Circuits
Wiring for elevators includes a requirement that some of the
electrical equipment associated with the elevator have
separate branch circuits. These include a separate branch
circuit for each of the following,
1. Car lighting, receptacles and ventilation
2. Car air-conditioning and heating units
3. Machine room/control space lighting and
receptacles
4. Hoistway pit lighting and receptacles
5. Any other utilization equipment associated
with the elevator
These separate branch circuits provide a
measure of safety to those maintenance persons working on the
elevator. The separate branch circuit allows the isolation of
circuits during the maintenance process. In addition, the
circuit being used for the A/C and heat units used in the
elevator car must be dedicated to that heating and A/C
equipment.
Inspecting
When inspecting power wiring for elevators, start by
identifying the components of an elevator system. The elevator
will have a car and a hoistway, which the car
travels up and down inside. You will also need to locate the machine
room or machine space and the control room or control space. Locate the elevator motor
controller. If it is outside the hoistway and in a space
you can walk into, it is the control room. Otherwise, it is
the control space. Use the same method to determine if the
mechanical equipment is located in the machine room or space.
Wiring Methods
The wiring method used for the elevator, hoistway and these
rooms or spaces must be on this list.
• Rigid Metal Conduit
• Intermediate Metal Conduit
• Electrical Metallic Tubing
• Rigid Nonmetallic Conduit
• Wireways
• Metal-Clad Cable
• Mineral-Insulated Cable
• Armored Cable
Some of the elevator equipment requires a
flexible wiring method. Flexible metal conduit, liquidtight
flexible metal conduit or liquidtight flexible nonmetallic
conduit can be used, as long as the length is limited to 6
feet or 1.8 meters. Liquidtight flexible nonmetallic conduit
can be used in lengths longer than 6 feet, but only on the car
or in the machine and control room/space. Flexible cords and
cables are permitted with some restrictions. They must be
components of listed equipment and they are limited to
circuits operating at 30 volts rms or less, or 42 volts dc or
less. These cords and cables are also limited to lengths of 6
feet or less. Hard-service cords and junior hard-service cords
can be used for flexible connections in the car without
voltage restrictions. Cables used for Class 2 power-limited
circuits can be used as long as they are properly supported
and protected from physical damage.
An important point to note, no matter what
wiring method is used, only wiring associated with the
elevator or required by another code (i.e., fire codes) can be
located in the hoistway, machine room/space or control
room/space. The only exception is wiring that bonds the
elevator rails to a lightning protection system. The down
conductors of the lightning protection system cannot be
installed in the hoistway. The main feeders for the elevator
can be installed inside the hoistway, but only with special
permission or if the driving equipment is located in the
hoistway.
Conductors
As in all parts of the Code, conductors must be large
enough to carry the designed load. Normally, 24 AWG copper is
the minimum size you can see. Smaller sizes are permitted if
they are listed for the purpose. Lighting requires a minimum
size of 14 AWG copper. Although it is compliant to install
parallel conductors as small as 20 AWG copper, as long as the
combined ampacity equals the 14 AWG. Use 620.13 to determine
feeder and branch-circuit conductor sizes.
Working Clearance
Electrical equipment must have working space provided
according to 110.26(A). There are exceptions to the working
clearance requirement in 110.26(A) that apply if it is ensured
that only qualified persons are working on the equipment (I
hope only qualified people work on the elevator I ride). These
exceptions include equipment that can be repositioned and
wired with flexible wiring method, equipment that can be
serviced while guards are in place, and equipment that has
uninsulated parts operating at 30 volts rms, 42 volts peak, or
60 volts dc.
Photo
1. Lighting switch installed by pit access door, required
by 620.24(B)
Hoistway
When inspecting the hoistway, look inside the pit access door
or open the lowest level elevator door. You must see a
lighting switch in a readily accessible location. When you
turn this switch on, you should see at least one 125-volt,
single-phase, GFCI-protected duplex receptacle located in the
pit. Trip the GFCI receptacle. Be sure the light stays on. The
light cannot be installed on the load side of a GFCI. Inspect
the wiring methods used in the hoistway. Make sure it is one
of the permitted methods listed above. Be sure that you see
only wiring associated with the elevator. The traveling cables
should be installed so that moving parts of the equipment will
not likely damage them. Guards may be required to help protect
the traveling cable.
Room or Space
As you inspect the control room/space or the machine
room/space, again you should first see a light switch located
at the point of entry. Turn the light on and you must see at
least one 125-volt, single-phase, GFCI duplex receptacle.
Again the light cannot be installed on the load side of a GFCI.
Somewhere in this space or room you must see at least one or
more disconnects. The disconnect for the car
lighting/receptacle/ventilation circuit must be located in
this area. This disconnect must be an "enclosed,
externally operable fused motor circuit switch or circuit
breaker" capable of being locked in the open position.
You should see another disconnect (with the same requirements)
if the elevator you’re inspecting has a heating or A/C unit.
The heat A/C unit must have a dedicated branch circuit. Any
other utilization equipment associated with the elevator must
have a disconnect in this space, although its only requirement
is to be capable of being locked in the open position.
Installing these disconnects in this location allows the
service person to quickly locate them. Each of the disconnects
requires a sign that identifies the location of the
supply-side overcurrent protective device. If there is more
than one elevator in this location, each disconnect must be
identified with the car they are associated with.
Photo
2. Elevator controller located in control room
Elevator Car
The elevator car must be wired with the same options listed
above. The wiring must be suitably supported and protected
from physical damage. Verify that the car lighting is not
installed on the load side of a ground-fault circuit
interrupter.
Main Power Supply
A person can easily be hurt if the equipment he is working on
starts inadvertently. To prevent this from happening, there
are requirements for one or more disconnects. Look for a
listed, enclosed, externally operable, fused motor circuit
switch or circuit breaker that is installed in the main power
supply conductors. This disconnect must be capable of being
locked in the open position. It must disconnect all ungrounded
conductors and be designed so that no pole can operate
independently. It must be installed in a readily accessible
location within sight of the controller. Turning off this
disconnect must not remove power to any of the required
lighting in the car, hoistway, or controller/machine rooms or
spaces. A person working on a driving machine or motion and
operation controller located out of sight of the first
disconnect, must be able to prevent it from operating. A
manually operated switch installed in the control circuit to
prevent starting will provide this extra measure of safety.
This switch must be located adjacent to the equipment. All
elevators with driving machines located in a remote machine
room or space must have another disconnecting means installed.
This disconnect must also open all ungrounded conductors and
be capable of being locked in the open position. As you can
see, many of these requirements are in place to prevent the
branch circuits and lighting associated with the elevator from
being turned on or off without the maintenance person’s
permission. The Code requires the motor controller and
other equipment associated with the elevator to be located in
a manner that would prevent unauthorized access (such as
behind locked doors or panels).
Photo
3. Externally operable fused motor circuit switch capable
of being locked in the open position
Photo
4. Manually operated switch in control circuit required to
prevent inadvertent starting of equipment
The electrician can help prevent injuries
caused by elevators if he installs the electrical equipment
according to Article 620. The inspector can also contribute by
verifying the installation meets the requirement of this
article. I’ve given you a start and covered many of the
basic requirements of the article. There are other, more
specific, requirements that you may need to enforce for the
installation you are inspecting. Read the Code and take
the book with you so you can refer to it during your
inspection.
1McCann,
Michael, PhD, CIH. "Deaths or Injuries Involving
Elevators or Escalators" The Center to Protect Workers’
Rights (2004)
2 Ibid
Rob Forister is an IAEI-certified
electrical inspector for Sheridan, Wyoming. He
carries a state of Wyoming master electrician
license. He is the secretary/treasurer of the
Wyoming Chapter of the IAEI and represented the IAEI as
an alternate member of CMP-12 for the 2005 cycle.
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