E: Portable Workbenches
This section covers laboratory
and shop workbenches that can be moved by sliding, rolling, etc. It
does not cover built-in workbench assemblies that are permanently attached
to structure surfaces. Such built-in assemblies must use appropriate
fixed-wiring methods to provide power for receptacles, lighting fixtures,
ventilation fans, etc., in accordance with the NEC.
Flexible cord and plug
assemblies may be used to provide ac power to portable workbenches only
- The branch circuit voltage supplying the workbench is 150V or less.
- The overcurrent protection device rating on the branch circuit supplying
the workbench is 20A or less.
- The flexible cord is no longer than 4.5 m (15 ft), is attached to the
workbench with an approved tapered rubber-bushing cord-grip fitting,
is no smaller than #14 AWG, is type-listed under the NEC as “Extra
Hard Usage” (Type SO, G, W, etc.), is protected from physical damage,
is routed to prevent tripping hazards, and is terminated in a listed
attachment plug and mating receptacle interface that has the proper
voltage and current rating for the branch circuit feeding the workbench.
- Each workbench has its own cord, attachment plug, and branch circuit
receptacle. Workbenches must not be parallel fed or daisy chained by
plugging their power cords into a receptacle located on another workbench.
- Each workbench wiring system has equipment-grounding protection that
consists of a correctly sized and identified equipment-grounding conductor.
This grounding conductor must be an integral part of the flexible cord.
Grounding circuit continuity must be provided by the branch circuit
wiring feeding the workbench, and at the interface between attachment
plug and receptacle.
- All metal surfaces of the workbench assembly that are likely to become
energized by an electrical fault are properly bonded to the equipment
grounding conductor in accordance with the NEC.
- The number of workbench receptacle outlets is limited to no more than
10 duplex receptacles or 3 linear meters (10 linear ft) of wire-mold
plug strip on a 15A branch circuit, or 13 duplex receptacles or 4 linear
meters (13 linear ft) of an approved multi-outlet assembly on a 20A
branch circuit. In any case, the continuous load fed by the workbench
outlet receptacles must not exceed 80% of the rating of the branch circuit
that feeds the workbench.
- Each workbench has proper seismic anchoring or other restraint against
unintentional movement so that the cord-and-plug AC input power assembly
is protected from damage resulting from tension, pinching, crushing,
etc. (See PUB 3000, Chapter 23, Seismic
- If the bench is fitted with a metallic or otherwise conductive work
surface, the workbench wiring system is protected by an approved GFCI.
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