camper wiring

[Jimmie]

Are RVs wired with a grounded neutral or an isolated neutral.

[Jimmie]

OOps, sorry I sent this to the wrong NG, answers still appreciated.

[Greg]

Every one I have seen was isolated neutral. There is a 3 wire plug on 120v 30a and 4 wire plug on 240v 50a. That is the standard. The bonding jumper is in the post or in the service panel that feeds the post if the post is not where the service point resides.

[John Hines]

Trailers are wired with a 4 wire, separate ground and neutral.

There isn't a good ground connection, so if there was a problem with the electrical, and a connected ground/neutral, there exists the probability that it would electrify all the metal in the vehicle.

Tying the ground and neutral together only applies in fixed location buildings, not anything mobile or portable.

[Jimmie]

That is what I thought too. Didnt know what NEC said about it but common sense still applies. I based my opinion on the fact that breaker panel in an RV would be considered a sub panel.

[zxcvbob]

Isolated neutral. The power feed from the RV park already had the ground and neutral broken out seperately -- you don't get to recombine them.

Even moble homes that are set permanently in place have to have the neutral isolated in the odd chance that something goes wrong with the ground connection, so the neutral doesn't energize the trailer's metal framing through the equipment ground.

Bob

[HorneTD]

The real answer is that depends. If the camper has a generator or inverter to supply electric power the answer is not as straight forward as some of these answers would have you believe. The campers transfer switch is unlikely to switch the neutral although some do. If the neutral is not switched by the transfer switch and it is bonded at the on board supply it will remain so even when you are running on park power. One simple way to avoid these problems is to use the cord for the park hook up as the transfer switch. Since the cord cannot be plugged into two places at once that will keep the bonding point of the on board power from getting connected to the park power outlet. With this method the on board AC power supplies are connected only to a receptacle that the on board AC wiring can be connected to when it is not connected to a park outlet.

-- Tom H

[Greg]

Why would they want to bond the neutral for the onboard generator? You would lose a significant degree of safety by doing it. That is why a portable generator doesn't bond the neutral.

[HorneTD]

The neutral has to be bonded or a ground fault current cannot flow back to the source and trip the Over Current Protective Device (OCPD). You bond the neutral of a separately derived system for the same reason that you bond the neutral of a service which is to provide a low impedance path for fault current to return to it's source.

-- Tom H

[HRL]

Ground Fault current is exactly why they can not be bonded. When plugged into campground outlets that are invariably Ground Fault type and of course have the ground and neutral bonded somewhere downsstream, the ground must be isolated in the trailer. If not there the campground GCFI will trip because some of the return current will flow in the ground wire. Once in a while you find an RV that has them connected inside the unit. To get power when plugged into the campground reciprocal they must use a two wire connection.

[HRL]

Forgot to add (you already noted that this is not the planned group) that this question would be best answered on:

alt.rv or rec.outdoors.rv-travel