3000W Chinese Gensets Info.

Ugly Dwarf wrote:
A quick update...

Last night I fired up the generator and ripped through a thick piece of redwood with no problem.

Your circular saw will pull in excess of 20 amps in locked or near locked rotor condition. You probably got close to that amount of current with the redwood you cut. That rules out a weak circuit breaker in the generator and even a faulty generator itself.

I confirmed that when set to 120, the voltmeter showed ~120. When the switch was set to 240, it showed ~240.

We are OK here - the saw did not go up in a ball of flames so the voltages are what they should be.

I then turned off the breakers on the pannel, unplugged the refridgerator and attempted to power up the trailer. This time it bogged down (as usuaal), but it popped the breakers on the genset.

This is where my understanding gets a little fuzzy.... the breakers you turned off on the pannel are, I assume, in the trailer. Did you turn ALL the breakers off, including the main breaker?

Thinking you turned everything off, the only connection to the generator would be the big black power cord, a junction box just inside the cord door, and a piece of 10-2/WG NMC running under the trailer and possibly up a wall into the pannel box. There should be NO physical connection between any of the wires in these cables following this path.

I have seen some pretty sloppy and scary electrical work in my days. Examples are staples and nails driven into a conductor or even bridging two conductors. Knots getting into the cables while someone is pulling them through drilled holes or raceways - rather than unknot the cable they just pull harder until the insulation is completely ripped off and exposes bare conductors. Steel angle or other conductive materials can be placed against the cable and vibration will abrade the insulation. An example would be wires run between the metal frame or cross members of your trailer and the subfloor or sleepers. None of these situations is suppose to exist - but they sometimes get past inspectors.

Now let's get back to possibilities in this situation.

The black wire inside the NMC sheathed #10 feed cable is connected to the circuit breaker. When the breaker is off, this wire should have no further connection to anything in the camper.

The white wire will be connected to a buss bar in the pannel box. The buss bar should not have any connection to any part of the camper other than the "long" slot on your duplex outlets.

The green or bare copper wire will be connected to a second buss bar. This buss bar will be connected to the metal framework of your camper.

"If" the neutral (white wire) and grounding wire (green or bare) are shorted together in the feed circuit for your camper, the metal frame of your camper will be "HOT" in reference to the opposite pole or winding in your generator. This situation can create a high current "ground loop" in a generator, which is isolated from true ground.

This ground loop would not exist when plugged into campground power since both the neutral and grounding wires ARE connected in the campground power pod. You would have a new situation known as a ground fault that a conventional breaker would not recognize and trip. Your could confirm this by plugging your camper into a 20 amp GFCI protected duplex outlet using your adapter - the GFCI should turn off.

Result of the loop/fault? What you are experiencing........

It sounds like a problem with the trailer wiring, but it seems odd that it works on shore power in a campground and off the plugs at my house

Yes, California, you very possibly have a potentially serious and dangerous problem lurking in your trailer. It is not my intention to try and scare anyone and I certainly hope I am not preceived to be overreacting. I cannot be 100% sure of what is going on since I am not there to run the proper test. Still, I would not take chances on the odds that I am wrong and it is something else.