Using RV Generator To Feed House

[Gino’s Garage]

So I have been going around and around trying to figure out if it’s possible and the best way to possibly do this without creating an unsafe situation. Basically what I am talking about is what the title says, using a vehicle mounted generator to feed your house as back up power.
So here are the issues as I see it:
The vehicle mounted generator has an internal neutral and ground bond as it only serves the vehicle that it’s connected to.
The house already has a neutral and ground bond at the main service. You would need to get rid of one of these connections, so that you have the correct fault current path back to the generator main breaker. So the RV has a transfer switch that disconnects the hots and the neutral, so when the RV is plugged into shore power then it’s not connected to the neutral ground bond in the generator any longer and it’s more like a sub panel. Seems to me that there is not really any easy way to feed your house with this generator and still keep it safe. Anyone have any thoughts on this?

 

[ActionDave]

You didn't mention a transfer switch on the house. If you have a transfer switch that switches the neutral then you are good to go. Or you could just not worry about the bond at the generator because I doubt there are going to be any metallic paths between the generator and the house.

 

[retirede]

Or you could just not worry about the bond at the generator……

Many in-vehicle generators are GFCI-equipped. If so, the bond in the house will cause it to trip.

 

[LarryFine]

If I'm not mistaken, the issue is neutral current on the cord's EGC because of both ends being bonded.

Would there be a compliant way to use a three-conductor cord, so there is no parallel EGC pathway?

 

[Little Bill]

Many in-vehicle generators are GFCI-equipped. If so, the bond in the house will cause it to trip.

Wouldn't that only trip the GFCI for the 120V outlets on the generator? If connecting to the house, you wouldn't need those receptacles anyway.

 

[retirede]

Wouldn't that only trip the GFCI for the 120V outlets on the generator? If connecting to the house, you wouldn't need those receptacles anyway.

Some have GFCI protection on the 240V connection.

 

[ActionDave]

If I'm not mistaken, the issue is neutral current on the cord's EGC because of both ends being bonded.

Would there be a compliant way to use a three-conductor cord, so there is no parallel EGC pathway?

I thought about that but didn't put it in my post because it was making me think too hard. You would lose your grounding electrode. That's the only problem I can think of right now.

 

[LarryFine]

I thought about that but didn't put it in my post because it was making me think too hard. You would lose your grounding electrode. That's the only problem I can think of right now.

The house end has one, and you could add one at the RV if really necessary.

 

[synchro]

If I'm not mistaken, the issue is neutral current on the cord's EGC because of both ends being bonded.

Would there be a compliant way to use a three-conductor cord, so there is no parallel EGC pathway?

With a 3-conductor cord (or even with a parallel EGC) there will be some voltage drop on the neutral conductor under load, and this voltage difference will appear between the body of the RV and the EGC/GEC of the house. So if someone stood on the ground in bare feet and touched the RV they could possibly get some current through their body. The worst case would be if there was an open on the neutral through the cord connection, and then the voltage on the RV body relative to earth ground could get elevated significantly. However, if a 3-wire cord (i.e., no EGC) to the house was fed by a GFCI in the RV, then more than ~5mA of leakage from the RV body to earth ground would trip the GFCI. There could be a possibility of the GFCI tripping if the RV body had a path to ground through metal stairs, etc. But if it was on a concrete pad or driveway that would be less likely. Whether unwanted tripping could happen would depend on the particular situation.

But without a GFCI being used, I think a parallel current path though an EGC would be a better alternative than no EGC. If there is an open on the neutral, then depending on the loads in the house the RV body could get a large voltage on it relative to ground. Of course the EGC could be open too, but it's less likely that both N and EGC would be open.

 

[Gino’s Garage]

Just saw these responses, sorry for my delay. I believe the main issue to be the parallel paths created by the two bonding points. As was pointed out a transfer switch that switches the neutral on the house is a good idea, only concern is the distance from the generator bond point to the grounding electrode connection could be quite far away and generally I thought that connection was to be as close as possible to the main bond connection. This is probably the closest you are going to get to something being complaint and safe where all objectionable current would be returning to the source in order to trip the generator main breaker.

 

[qcroanoke]

Where in the RV are you going to hook your cord so it can feed your house?

 

[tom baker]

Wouldn't that only trip the GFCI for the 120V outlets on the generator? If connecting to the house, you wouldn't need those receptacles anyway.

Correct. The genny does not have GFCI, only the 120 receptacles

 

[Gino’s Garage]

Where in the RV are you going to hook your cord so it can feed your house?

I have a 50amp receptacle that feeds out of the main panel via a 50a breaker in the RV. The RV does not have GFIs other than the bathroom and outdoor receptacles, it’s a vintage RV, a 1984 Bluebird Wanderlodge. The generator is wired into a manual transfer switch, this is a 12kw Powertech Diesel generator.