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ADDITIONAL GROUNDING INFORMATION & SAFETY TIPS
POSSIBLE CAUSES OF INJURY OR FATALITY
• Shocks & electrocution to users from improper use – improper connection to structures, such as residences,
of
fi
ces, shops and trailers.
SAFE WORK PRACTICES
• Maintain and operate portable generators in accordance with the manufacturer’s use and safety instructions
• Do not attach a portable generator directly to the electrical system of a structure (home, of
fi
ce or trailer) unless the
generator has a properly installed open-transition transfer switch.
• Always plug electrical appliances and tools directly into the generator using manufacturers supplied cords. Use heavy-
duty extension cords that contain a grounding conductor (3-wire
fl
exible cord and 3-pronged cord connectors).
• Proper grounding and bonding prevent shocks and electrocutions
• Use ground-fault circuit interrupters (GFCIs) as per the manufacturer’s instructions.
• Visually inspect the equipment before use; remove defective equipment from service; mark or tag it as unsafe for use.
GROUNDING REQUIREMENTS (Portable and Vehicle-mounted Generators)
Under the following conditions, OSHA directs that the 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.
• The noncurrent-carrying metal parts of equipment (such as the fuel tank, the internal combustion engine, and
the generator’s housing) are bonded to the generator frame, and the equipment grounding conductor terminals
are bonded to the generator frame.
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, of
fi
ce, 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 manu-
facturer’s installation instructions by a quali
fi
ed electrician.
SAFE WORK PRACTICES FOR PORTABLE TOOLS
• 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.
• Use battery-operated tools where possible.
BONDING VERSUS GROUNDING
Bonding and grounding are separate requirements for generators and other electrical distribution systems.
Grounding means the connection, or the establishment of a connection, of an electric circuit or equipment to
reference ground, which includes the generator’s frame. Bonding is the intentional connection between the
grounded circuit conductor (neutral) and the grounding means for the generator, which includes the genera-
tor’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 con
fi
rmed via testing by a competent electrician with the correct equipment, and the
ohmic resistance should measure near zero and must not be intermittent, which indicates a loose connection.
