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Full Version: Trailer electrical question: can I separate the common from the ground
F-Body Road Racing and Autocross Forums > Community > General Discussion
tonycook
I sometimes plug my trailer into a GFI outlet. As soon as it is plugged in, the GFI outlet is tripped. I figure the GFI is sensing that the common and ground are connected somewhere in the trailer. My thoughts are that the common and ground are connected in the breaker box in the trailer. (I can't check that now because I'm at work and won't get home until the morning.) Is there any danger in disconnecting the common from the ground? I would leave the common and ground circuits complete to the power inlet that connects to the power pole or generator.

Thanks,
Tony
Machine
GFIs are designed with a balance-checking circuit to sense whether there is any differential in the current going out on the hot lead versus the return path of the neutral (e.g. 'other' path).

I don't know AC trailer wiring - why would the ground and neutral be connected in the trailer? I know that in household electricity, you want only one main grounding point between the neutral and ground. Seems that if your trailer has that connection also that there would be a ground loop, which is 'usually' bad.
tonycook
It appears to be wired just like a house. Aren't the common and ground connected at the breaker box in a house?
Machine
Yes, the neutral and ground are connected in the house. The idea is that if there is a short in the system, the current (juice) has another path to ground instead of going through your body and also will allow the circuit breaker to trip. In normal operation, there is no current on the ground wire. If you introduce another connection, you will have the potential hazard of current flow in the ground conductor because now the hot wire has 2 paths to come back to the main panel. I would guess that you could measure current on your ground wire and THAT IS BAD for sure. If you have any loose ground connections like conduit, you are creating a potential arcing fire hazard.
sgarnett
It sure sounds like there is a short that needs to be tracked down.
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