Camper electrical question

[Jmclain21917]

I have a camper everything was fine until one night a few weeks ago all the power stopped working for no reason at all nothing changed in the camper but the power just stopped working. I had lent out my multi meter and had gotten it back shorted out, I did not know at first that it was shorted out before testing with the meter I unplugged from the shoreline and made sure all wires were tight. I replaced the main breaker and another breaker still no power, so I attempted to test the voltage with my multimeter when I place the red lead on the screw and placed the black lead on the negative bus there was a little spark and the power came on. I purchased a new meter and placed the leads the same way and no power but with my old shorted meter doing it again with the leads power comes on and stays on which to say the least is weird. Anyone of the electricians please help me make sense of this I am attaching photos so you can see what I am referring too.

 

[Lucien Nunes]

Am I correct in understanding that:
a) The V/Ω and COM sockets of your multmeter are shorted together? It's extremely unlikely, I've never seen or heard of this happening, obviously it carries a risk of arc flash injury especially when used with conventional non-fused test leads.
b) Placing the (shorted together) probes of the meter between the outgoing hot wire from one breaker and the ground terminal caused equipment in the camper to receive power?

Obviously these two scenarios are each unlikely, but as a coincidence almost unimaginable. If correct, a logical explanation is that the wiring in the shoreline or outlet feeding it is faulty and crossed. Suppose the hot is connected to the panel neutral and the neutral is broken. There would be a circuit from shoreline hot, via neutral buss to appliance, back to the breaker hot terminal, via meter probes to ground buss, to ground via shoreline. Or to neutral, if that is crossed in the shoreline too. The appliance would be energised with reverse polarity - the black circuit wire is seeing neutral or ground and the white seeing hot - but it would still function.

Given the suspicion this casts on the shoreline connections, it seems to me that there is a risk of the bodywork of the camper becoming live and creating a serious shock risk. I would definitely disconnect the power and start tracing from shoreline to panel using continuity tests only, not energising the panel again with 120V until the correct connection of hot, neutral and ground have been proven all the way from the utility supply to the outgoing circuits from the camper panel.

 

[Jmclain21917]

Am I correct in understanding that:
a) The V/Ω and COM sockets of your multmeter are shorted together? It's extremely unlikely, I've never seen or heard of this happening, obviously it carries a risk of arc flash injury especially when used with conventional non-fused test leads.
b) Placing the (shorted together) probes of the meter between the outgoing hot wire from one breaker and the ground terminal caused equipment in the camper to receive power?

Obviously these two scenarios are each unlikely, but as a coincidence almost unimaginable. If correct, a logical explanation is that the wiring in the shoreline or outlet feeding it is faulty and crossed. Suppose the hot is connected to the panel neutral and the neutral is broken. There would be a circuit from shoreline hot, via neutral buss to appliance, back to the breaker hot terminal, via meter probes to ground buss, to ground via shoreline. Or to neutral, if that is crossed in the shoreline too. The appliance would be energised with reverse polarity - the black circuit wire is seeing neutral or ground and the white seeing hot - but it would still function.

Given the suspicion this casts on the shoreline connections, it seems to me that there is a risk of the bodywork of the camper becoming live and creating a serious shock risk. I would definitely disconnect the power and start tracing from shoreline to panel using continuity tests only, not energising the panel again with 120V until the correct connection of hot, neutral and ground have been proven all the way from the utility supply to the outgoing circuits from the camper panel.

What could cause this to happen all of a sudden with nothing being changed in the camper or the shoreline it been setup for years with no problem how can this happen?

 

[Lucien Nunes]

I can't explain it, other than that perhaps the polarity of the shoreline was always wrong (which would not have stopped it working) but now the neutral connection (to the hot prong) has broken away, so that the circuit is only complete when the missing neutral (on the hot breaker terminal) is linked to ground by your meter probes.

There's no point speculating. A systematic sequence of continuity tests will find the problem very quickly, and then you will be able to see for real what caused it. Test from the male to female ends of the shoreline, each prong to each of the three female contacts. If that's OK, plug the shoreline into the camper but take the plug end of the shoreline inside next to the panel. With all the breakers off, test shoreline hot, neutral and ground prongs to each of hot, neutral and ground busbars. Then check the polarity at the outlet on the wall that you are using to feed the shoreline.

 

[loz2754]

What setting was the multimeter set on?
The reason I ask is, if it was set to read amps instead of volts, the meter itself becomes part of the circuit, and may have overloaded its internal circuitry. (Just thinking out loud, as most meters have internal protection).

 

[mainline]

What setting was the multimeter set on?
The reason I ask is, if it was set to read amps instead of volts, the meter itself becomes part of the circuit, and may have overloaded its internal circuitry. (Just thinking out loud, as most meters have internal protection).

The position of the multimeter switch wouldn't make much difference.
But the position of the leads would if they were put in Amps mode.