frame of a portable generator need not be
grounded (connected to earth) and that the
frame may serve as the ground (in place of
the earth):
•
The generator supplies only equipment
mounted on the generator and/or cord-
and plug-connected equipment through
receptacles mounted on the generator,
§ 1926.404(f)(3)(i)(A), and
•
The noncurrent-carrying metal parts of
equipment (such as the fuel tank, the inter-
nal combustion engine, and the generator’s
housing) are bonded to the generator
frame, and the equipment grounding con-
ductor terminals (of the power receptacles
that are a part of [mounted on] the genera-
tor) are bonded to the generator frame,
§ 1926.404(f)(3)(i)(B).
Thus, rather than connect to a grounding
electrode system, such as a driven ground
rod, the generator’s frame replaces the
grounding electrode.
If these conditions do not exist, then a
grounding electrode, such as a ground rod,
is required.
If the portable generator is providing electric
power to a structure by connection via a
transfer switch to a structure (home, office,
shop, trailer, or similar) it must be connected
to a grounding electrode system, such as a
driven ground rod. The transfer switch must
be approved for the use and installed in
accordance with the manufacturer’s installa-
tion instructions by a qualified electrician.
Major Causes of Injuries and Fatalities
•
Shocks and electrocution to users from
improper use.
•
Shocks and electrocution to utility workers
from improper connection to structures, such
as residences, offices, shops and trailers.
Safe Work Practices
•
Maintain and operate portable generators
in accordance with the manufacturer’s use
and safety instructions.
•
Never attach a portable generator directly
to the electrical system of a structure
(home, office or trailer) unless the genera-
tor has a properly installed open-transition
transfer switch.
•
Always plug electrical appliances and tools
directly into the generator, using the appli-
ance manufacturer’s supplied cords. Use
heavy-duty extension cords that contain a
grounding conductor (3-wire flexible cord
and 3-pronged cord connectors).
•
Proper grounding and bonding are a means
to prevent shocks and electrocutions.
•
Use ground-fault circuit interrupters (GFCIs)
as per the manufacturer’s instructions.
•
Do not connect a generator to a structure
unless the generator has a properly
installed transfer switch.
•
Visually inspect the equipment before use;
remove defective equipment from service;
mark or tag it as unsafe for use.
Grounding Requirements for Portable
and Vehicle-mounted Generators
Under the following conditions, OSHA
directs (29 CFR 1926.404(f)(3)(i)) that the
Fact
Sheet
Grounding Requirements
for Portable Generators
Portable generators are internal combustion engines used to generate electricity.
They are useful when temporary or remote power is needed, and are commonly
used during cleanup and recovery efforts following disasters.
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