Generator Grounding

[DanS26]

I have recently reviewed a homeowner site with the generator grounded as follows:

1. the main distribution panel is the first disconnect and has the neutral bonded to the ground system with a properly sized GEC connected to a properly sized grounding electrode.

2. the main grounding electrode is bonded underground to a second electrode approximately 50 feet away from the first electrode. I believe this satisfies NEC grounding requirements for a low impedance path.

3. at the second electrode site is a generator that is NOT a separate derived device (ie a floating neutral). The generator has a GEC connected to the second electrode.

My questions:

1. Does the distance of the second electrode (and the inherent resistance) create a problem in the case of a nearby lightning strike? In other words, will that resistance force high voltage into the generator as an alternative path?

2. Does the generator GEC in effect create a ground loop? (ie the loop being created by the generator EGC back to the main panel)

3. Would you recommend to disconnect the generator GEC to the second electrode?

 

[tom baker]

Does the transfer switch transfer the neutral?

 

[ActionDave]

.......
1. Does the distance of the second electrode (and the inherent resistance) create a problem in the case of a nearby lightning strike? In other words, will that resistance force high voltage into the generator as an alternative path?

2. Does the generator GEC in effect create a ground loop? (ie the loop being created by the generator EGC back to the main panel)

3. Would you recommend to disconnect the generator GEC to the second electrode?

I would leave things just as they are. Since the GEC at the generator is connected to the house grounding electrode system there is no issue with ground loops or lightning strikes. That is only a problem when the ground rod and conductor are isolated from the rest of the GES.

 

[DanS26]

Does the transfer switch transfer the neutral?

No. The neutral is not switched and it is also not bonded to ground in the generator. The generator is set up to float the neutral.

 

[Haji]

The generator is set up to float the neutral.

You have an ungrounded generator power system.

 

[jumper]

You have an ungrounded generator power system.

Er, how did you come up with that?

 

[Sahib]

Er, how did you come up with that?

From this?

The generator is set up to float the neutral.

 

[jumper]

From this?

I believe that the OP just has a non SDS set up, as he stated, not a ungrounded system.

3. at the second electrode site is a generator that is NOT a separate derived device (ie a floating neutral). The generator has a GEC connected to the second electrode.

I think this what he has:

http://www.imsasafety.org/journal/ma03/Fig 2.jpg

 

[Sahib]

Well, if there is continuity between generator neutral and EGC, no problem.

 

[augie47]

I see no problem with the arrangement, however IMO, it should be noted that there is still a requirement for an equipment grounding conductor to be installed with the generator conductors.

 

[DanS26]

I see no problem with the arrangement, however IMO, it should be noted that there is still a requirement for an equipment grounding conductor to be installed with the generator conductors.

Yes, the generator has a properly installed equipment grounding conductor which is incorporated into a 4 wire connection to transfer switch and main disconnect panel all properly sized.

 

[DanS26]

Thank you everyone for your help.