ELECTRICAL SAFETY DESIGN

Wiring Design and Protection - Support, Enclosure, and Equipment Grounding

If metal parts or tools are likely to be used in wet or conductive locations, they do not have to be grounded if their power is supplied through an isolating transformer with an ungrounded secondary winding of not over 50 volts.

Listed or labeled portable tools and appliances protected by an approved system of double insulation, or its equivalent, need not be grounded. The equipment shall be distinctively marked to indicate that the tool or appliance uses an approved system of double insulation.

The metal parts of the following non-electrical equipment shall be grounded:

Frames and tracks of electrically operated cranes

Frames of non-electrically driven elevator cars to which electric conductors are attached

Hand operated metal shifting ropes or cables of electric elevators

Metal partitions, grill work, and similar metal enclosures around equipment of over 750 volts between conductors.

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