Dethleffs RCD Issue

Jul 3, 2020
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Hi guys, just bought a Dethleffs Rally Nomad 2009. We’ve had it plugged in to the mains and been doing all the basic checks for a couple of days. All seemed to be ok (although we think we need a new battery) but suddenly today the caravan is tripping the house electrics and there is nothing plugged in. Also the test button on the caravan RCD is not working. Any ideas please ?
 
Oct 8, 2006
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You have a fault on the EHU cable or its connections. The RCD always trips for something downhill of its circuit location. The RCD in the van would trip if it was a van fault (and so might the house) but if it is only the house tripping then the fault lies before the caravan RCD. Simples.
 
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Nov 6, 2005
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You have a fault on the EHU cable or its connections. The RCD always trips for something downhill of its circuit location. The RCD in the van would trip if it was a van fault (and so might the house) but if it is only the house tripping then the fault lies before the caravan RCD. Simples.
If there's a difference in sensitivity, a fault within the caravan could cause the house RCD to trip before the caravan RCD - there are differences in sensitivity.
 
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Oct 8, 2006
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There will be no difference in sensitivity. In normal domestic use (caravans included) the trip current is 30mA. There may be a small time difference depending on the leakage current - it must trip within 300mS at its rated current, and within 40mS at five times its rated current.

The only reason that the house is tripping and the caravan is not is that there is a fault between the house connection and the input to the caravan power box. I would suggest checking the EHU cable visually for damage, and even more so disassemble the plug and socket on the ends as they can overheat and cause pin displacement.

Another thought - does the house still trip if the RCD is in the off position in the caravan? That should give a pointer in the right direction.
 
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Nov 6, 2005
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There will be no difference in sensitivity. In normal domestic use (caravans included) the trip current is 30mA. There may be a small time difference depending on the leakage current - it must trip within 300mS at its rated current, and within 40mS at five times its rated current.

The only reason that the house is tripping and the caravan is not is that there is a fault between the house connection and the input to the caravan power box. I would suggest checking the EHU cable visually for damage, and even more so disassemble the plug and socket on the ends as they can overheat and cause pin displacement.

Another thought - does the house still trip if the RCD is in the off position in the caravan? That should give a pointer in the right direction.
There can be significant differences in trip time - none can exceed the maximum but some can be much faster.

I fitted mains electrics with an RCD top our first caravan - the trip time was only just inside the maximum - at the suggestion of the electrician who was test certifying it, I replaced the RCD with a quality domestic type which tripped in a quarter of the time.
 
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Oct 8, 2006
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You are still missing the point. The OP said that the test button in the caravan does not work either (OK, I suppose he didn't say if the mains was actually on when he tried it!) but nonetheless switching the RCD off mechanically and then connecting the EHU will show if it is a caravan or cable fault.
 
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Mar 14, 2005
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Basically the house trip is doing what its supposed to do which is to disconnect the supply when a fault condition is detected. An RCD tripping is not a trivial event on an established circuit.

It is always a worry when we get a question like this one, becasue if the fault has so far baffled the questioner, then I have concerns for the capability of the questioner to follow any fault finding advice with safety.

It therefore needs someone with a good knowledge of electrics to a professional level to resolve it and to check it is in fact all working correctly.
 
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Jul 3, 2020
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Basically the house trip is doing what its supposed to do which is to disconnect the supply when a fault condition is detected. An RCD tripping is not a trivial event on an established circuit.

It is always a worry when we get a question like this one, becasue if the fault has so far baffled the questioner, then I have concerns for the capability of the questioner to follow any fault finding advice with safety.

It therefore needs someone with a good knowledge of electrics to a professional level to resolve it and to check it is in fact all working correctly.
Thankyou all, we will do the basic checks as suggested but then get a professional in if required 🙂
 

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