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Connecting Portable Generator with Bonded Neutral to House Panel

Connecting Portable Generator with Bonded Neutral to House Panel

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  #1  
Old 10-05-15, 09:00 AM
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Connecting Portable Generator with Bonded Neutral to House Panel

What is the correct way to connect a Portable Generator with Bonded Neutral to House Panel? There is some conflicting information on the web about this subject, so I thought I would post to get some clarification.

The generator I am considering for this project states it has a bonded neutral and GFCI outlets and 6800/8500 running/surge watts. I believe most generators manufactured within the last couple of years require GFCI outlets. The owners manual states if the gen is connected to a house service it should use a transfer switch that switches the neutral (3 pole). It does not give instructions on removing the neutral bond in the generator.

I see there are neutral switch kits that add to a standard none neutral switching transfer switch. My municipality allows the use of a backfeed breaker and UL approved interlock, which I prefer, but I don't see a method to switch the neutral. What would be the best type of tranfer switch to do this ?
 
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Old 10-05-15, 09:05 AM
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It's a topic where there is not a clear right or wrong. There are advantages and disadvantages with each approach. First thing I think you should do is check with the local inspector to see if they want you to do anything with the neutral bond in conjunction with the interlock. My guess is they will say to leave it as-is.
 
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Old 10-05-15, 09:12 AM
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Will the GFCI trip if I do not switch the neutral ? If so, is there anything that can be done to prevent the tripping ?
 
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Old 10-05-15, 09:23 AM
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Does the generator have GFCI on the 240/120V receptacle? Likely the 14-30L?
 
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Old 10-05-15, 10:22 AM
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According to the manual the GFCI is on the 120v/20 A receptacles, but not on the 240/30 A 14-30L. I was planning on running a cooling fan off of the 120 V receptacles during operation, if possbile
 
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Old 10-05-15, 11:07 AM
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The neutral bond can stay as long as there is not a GFI breaker on the generator protecting the 240v output. If there was..... it would trip with the neutral and ground bonded.
 
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Old 10-05-15, 12:05 PM
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My opinion is that you're ok using the generator as-is feeding your interlocked breaker from the 14-30L receptacle, using an appropriate cord and inlet. You can still use the 120V receptacle for the cooling fan without a problem.
 
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Old 10-05-15, 12:14 PM
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My understanding is that it is mandatory to switch the neutral. Otherwise the ground and neutral are connected at both the box and the generator; and that isn't safe.
Don't really know, but I can see that tripping a GFCI.
 
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Old 10-05-15, 12:25 PM
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Yes...they are connected at both ends but it is TWO distinct pieces of wire...... not one wire serving both functions. There is nothing dangerous about combining the ground and neutral at the genny. It actually comes that way from the factory.

In this case.... the OP doesn't have GFI protection on the 240v receptacle. If he did.... then the bond would need to be opened.
 
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Old 10-05-15, 12:28 PM
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I thought that created a ground loop that has dangerous possibilities
 
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Old 10-05-15, 12:33 PM
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disregard this post is was an error.
 

Last edited by edge10; 10-05-15 at 12:56 PM.
  #12  
Old 10-05-15, 01:17 PM
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If the 240 volt receptacle on the generator leads to tripping of a ground fault circuit interrupter on the generator and nothing else seems easy then you might unhook the green wire from its terminal in the male receptacle on the wall.

Actually nothing bad will happen if a generator with neutral and ground bonded feeds a panel with neutrals and grounds bonded.
 
  #13  
Old 10-05-15, 01:37 PM
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In a normal circuit yes it would be a problem to have a bonded neutral and ground, but in a temporary generator feed it is much less of a concern. It is more of a theoretical issue, but given that your generator cord is going to have an insulated ground conductor, even that is somewhat implausible. You will have created a parallel neutral feed, but since we're talking a main panel neutral and ground really are the same thing at that point. The generator being bonded is sort of like the service entrance mast or meter socket box in that the neutral and ground are bonded at multiple points through them. The neutral is technically an insulated conductor running through the mast, but it's sometimes bonded at the top of the mast where the ACSR drop lashes, bonded in the meter can to the metal box, sometimes bonded via a bonding bushing, and bonded again in the main panel; the steel framework is electrically indistinguishable from the neutral conductor itself. Adding the generator frame to what bonding already exists in the service entrance really is not a big leap.
 
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