Grounding requirements for generators con-
nected via transfer switches are covered by
Article 250 of the National Electrical Code
(NEC).
Safe Work Practices for Portable Tools
include:
•
Do not use underrated cords—replace
them with appropriately rated cords that
use heavier gauge wires.
•
Never use electrical tools or appliances
with frayed cords, missing grounding
prongs, or damaged or cracked housings.
•
Use double-insulated tools and equipment
distinctively marked as such, where possi-
ble.
•
Use battery-operated tools, where possible.
Verification by Testing
The integrity of the connection between the
generator’s frame and the equipment
grounding terminals of power receptacles is
important to the safe use of the equipment.
The connection may be confirmed via testing
by a competent electrician with the correct
This is one in a series of informational fact sheets highlighting OSHA programs, policies or
standards. It does not impose any new compliance requirements. For a comprehensive list of
compliance requirements of OSHA standards or regulations, refer to Title 29 of the Code of Federal
Regulations. This information will be made available to sensory impaired individuals upon request.
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equipment. The ohmic resistance should
measure near zero and must not be intermit-
tent, which indicates a loose connection.
Bonding Versus Grounding
Bonding and grounding are separate require-
ments for generators and other electrical dis-
tribution systems. Grounding means the con-
nection, or the establishment of a connec-
tion, of an electric circuit or equipment to ref-
erence ground, which includes the genera-
tor’s frame. Bonding is the intentional con-
nection between the grounded circuit con-
ductor (neutral) and the grounding means for
the generator, which includes the generator’s
frame. Thus, effective bonding of the neutral
conductor to the generator’s frame is also a
concern for the safe use of the equipment. As
with grounding terminal connections, proper
bonding of the neutral terminal of a power
receptacle may be confirmed via testing by a
competent electrician with the correct equip-
ment, and the ohmic resistance should mea-
sure near zero and must not be intermittent,
which indicates a loose connection.
U.S. Department of Labor
www.osha.gov
(800) 321-OSHA
For more complete information:
DSTM 10/2005
14
