Portable or semi-portable generators

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Moderator Post (s) for this thread: > Grounding generators and separately derived systems by Billhart on 01/11/2009 > Grounding Electrodes by Billhart on 01/11/2009 > Not True by homebild on 01/11/2009 > And By the Way by homebild on 01/11/2009 > Required grounding Electrodes by Billhart on 01/11/2009 > I Love it when the big boys go at it!!! by Jasper on 01/13/2009 > Ground wire by Billhart on 01/11/2009

For truly portable generators OSHA requires them to be grounded. And unless there is something specific in the OSHA rules about what can serve as a ground electrode then it follow the NEC.

But the typical small portable generator there is no real practical need to connect it to a ground electrode system. You don't have the conditions that exist on system run from high tension power lines.

However, if you already have "grounded strucutre" such as metal pipe or a framework for a steel building bolted to concrete base then it should be connected to that.

I am talking about 3 to 7 KW generators that might be found on a job site.

But the neutral is bonded to the generator "ground" terminal.

However, more and more "portable" generators are being connected standby power to a house, HOPEFULLY THROUGH A LEGAL TRANSFER SWITCH.

In that case the grounding is down through the house ground electrode system.

The generator neutral is kept isolated from the generate case. And 4 wires are run to the house. 2 Hots, neutral, and ground equipment conductor.