Portable Generator for Back feeding Residential Panel

edward

Senior Member
Location
CA
Occupation
Electronologist
You are not. Somebody has to keep me on my toes.
The only thing that come to mind, if the frame of the generator gets energized with the neutral disconnected from the frame.
I thought about this, I don't know what the voltage to earth ground will be if the frame does get energized. Next time I am out I will check and see.
 

Dsg319

Senior Member
Location
West Virginia
Occupation
Journeyman Electrician
I thought about this, I don't know what the voltage to earth ground will be if the frame does get energized. Next time I am out I will check and see.
Yes, would be interesting to see what the readings are with a low-impedance voltmeter.
 

jap

Senior Member
I don't see why the voltage to ground measurement would matter unless there's something that could keep a person from making contact between the frame and an un bonded neutral of a generator.

Which there isn't.


JAP>
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
So I did remove the Bonded Neutral Jumper Wire inside the generator to use with a Bonded Neutral Service Panel via Backfeed Breaker with Interlock. The Tag I will put on the Generator Will Read:

The Neutral Bonding Jumper has been removed inside this Generator to be used to feed a Bonded Neutral Service Panel with a Back Feed Breaker
This Bonded Neutral Jumper has to be re-installed to use this Generator as a Stand Alone in the Field.


Just wanted to get others input on this wording for the Tag

Thanks
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Engineer
I would just label it Floating Neutral. That should tell an electrician what he needs to know and most people won't know what it means. I'm not so sure that having it grounded is required "in the field". Would depend on size, worksite, and if OSHA rules are involved. There are many many portable generators which are floating neutral that people use standalone outside all the time. I have a 12KW floating neutral generator with a lot of outlets on the front and it that came from the factory that way. Newer ones perhaps not if they are NRTL Listed.
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
It has GFI's on the 120v outlets and i would think that the neutral needs to be bonded for them to work correctly
 

jap

Senior Member
To me the wording confuses the issue and puts all the responsibility on your suggestion.

If I were going to put a sign on a generator I wouldn't tell them what "I" did, or, what " the next person" needs to do.

I also don't see what the wording about the back fed breaker would have to do with anything.

If I were worried about the neutral to ground bond and had to put a sign on it , I'd simply put,

"Verify neutral bonding connection as needed prior to use".

JAP>
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
It has GFI's on the 120v outlets and i would think that the neutral needs to be bonded for them to work correctly
Not really, it would be like the generator sitting on a concrete pad, the pad is not bonded to the generator either. The gfi is looking for current to return from a different path than the neutral. With bond at the house, the ground from the house bonds the generator when connected. This effectively nullifies the gfi protection because any fault will come back through the neutral. Using the generator without connecting to a house isolates the hot and neutral, so current only has a return path between the two. If the hot goes to the frame of the generator or anything else, no shock possible, due to no return path. Just like a bird on a hv line.
 

jap

Senior Member
Not really, it would be like the generator sitting on a concrete pad, the pad is not bonded to the generator either. The gfi is looking for current to return from a different path than the neutral. With bond at the house, the ground from the house bonds the generator when connected. This effectively nullifies the gfi protection because any fault will come back through the neutral. Using the generator without connecting to a house isolates the hot and neutral, so current only has a return path between the two. If the hot goes to the frame of the generator or anything else, no shock possible, due to no return path. Just like a bird on a hv line.


There actually is a potential for shock if you get between the frame of the generator and the unbonded neutral of the generator unit itself.
Which is what I was referring to in post #23

JAP>
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
As long as the Generator is plugged into the Inlet box on house it will have a Grounding Conductor that will ground the frame and the neutral conductor that will be Bonded at the service panel. But when it is not being used for this application, then the Bonding Jumper should be installed on Generator. That's why the Tag must be installed to let others know its been removed.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support


There actually is a potential for shock if you get between the frame of the generator and the unbonded neutral of the generator unit itself.
Which is what I was referring to in post #23

JAP>
Yes, but you would have two failures there, the hot energizing the frame, and the neutral becoming exposed.
 
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