Grounding of generators

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Senior Member
It has come to my attention that portable Honda generators are not properly grounded by the manufacturer, and is stated so in their manual. This can potentially become a very hazardous condition, since the generator is a potential source of electrical shock if not grounded properly.

In the Honda manual it states the following on Ground System:
Honda portable generators have a system ground that connects generator frame components to the generator terminals in the AC output receptacles. The system ground is not connected to the AC neutral wire. If the generator is tested by receptacle tester, it will not show the same ground circuit condition as for a home receptacle.

Special Requirements
There may be Federal or State Occupational Safety and Health Administration (OSHA) regulations, local codes, or ordinances that apply to the intended use of the generator. Please consult a qualified electrician, electrical inspector, or the local agency having jurisdiction.

The intent of the NEC is to reference all non-current-carrying metal parts of equipment to the generator frame using the equipment grounding conductor terminals of the receptacles to form an effective ground-fault current path. In order for the ground-fault current to return its source the equipment grounding conductor and grounded (neutral) conductor must be bonded together.

The NEC requires all non-current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, to be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path. (equipment grounding conductor)

Definition: Effective Ground-Fault Current Path. An intentionally constructed, permanent, low-impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source.

The NEC clearly states in Section 250.34(A) that the frame of a portable generator, is not required to be grounded (referenced to earth by using a grounding electrode system), but that the frame is permitted to serve as the grounding electrode for a system supplied by the generator under the following conditions:
(1) The generator supplies only equipment mounted on the generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and
(2) The non-current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.
does anybody have any input?

Ed MacLaren

Senior Member
Re: Grounding of generators

It may be time for a rule, similar to the one in effect in Canada, that requires generator manufacturers to clearly indicate on the exterior of the machine whether the neutral is bonded to, or isolated from, the generator frame.

Then, a competent electrician can take the necessary steps to ensure a safe installation.


[ September 03, 2003, 06:26 PM: Message edited by: Ed MacLaren ]
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