Generator Grounding Safety

[jeff43222]

I've been assigned to review and update the corporate electrical safety manual at the office, probably since I'm the new guy, and because I actually have field experience.

One item that is puzzling me is this statement about portable generators I came across:

Note that grounding a generator using a grounding rod can actually increase the severity of a shock...

I asked one of our CADD guys who is a former master electrician, as well as a very experienced PE, and they both disagreed with the statement. I'm also having a hard time understanding how this could be true.

Anyone have any insight on this?

 

[don_resqcapt19]

I tend to agree with the statement. If the generator is floated and has no connection to earth, that possibility of getting a shock between either of the circuit conductor and earth small. Most portable generators are too small of a sytem to build up enough capacitance between the generator system and the earth to result in a shock hazard. I have watched some experiments with this idea that showed with an isolated generator, that is no connductor bonded to the frame, you cannot flow enough current to trip the a GFCI when you directly connect any of the generator system conductors to a grounding electrode. As soon as you make a bonding connection to the frame, in many cases with the generator frame sitting on the ground, you can get the GFCI to trip when connecting a system conductor to the earth. Remember current is only trying to get back to its source. If you are part of the path back, then there is a shock hazard. If there is no path back, as in the isolated small generator, there is no shock hazard. Note that we are only talking about a shock hazard to ground, there is always a shock hazard between the system conductors.
Don

 

[Fubar411]

So I have a small gas powered generator (it has a grounding pole). If I mount the generator so that it is isolated from earth, it is safer than if I ground it per manufacturer specs?

 

[iwire]

So I have a small gas powered generator (it has a grounding pole). If I mount the generator so that it is isolated from earth, it is safer than if I ground it per manufacturer specs?

Most likely yes.

If the generator is isolated you can not become part of the circuit.

Unless you grab both line conductors which grounded or not will always toast you.

 

[boboelectric]

Then the $60 G.F.C.I. adapter is just to make the O.S.H.A. man go away?

Bob O.84,Pa.15330