240v hook up tripping RCD

Later this year I'll be getting round to fitting an RCD in the van, but currently use the OG electric hook up which has worked fine up until now...

There are only two outlets from the hook-up, one is to the fridge socket, the other to a single socket in the van. When either is utilised, it trips the house (or campsite) RCD - plugging just the hook up lead in is fine, but as soon as there is any demand on the system she trips.

If I plug the fridge directly into an extension lead, it behaves - so as far as I can tell the fridge itself is OK - so I suspect a wiring issue, but am puzzled as to why both circuits cause the issue. They branch off independently from the hook up.

Next test is the hook up lead itself, I need to locate a spare to try out.

Worked fine when last used - but this was 2 years ago, prior to a substantial resto job involving the van being in the oven - has it baked the insulation off the wiring, or could a bit of mild corrision (greeny copper type, not rust) in the hook up socket cause this?

 

Check there is no Moisture anywhere
The tiniest bit can cause it to trip

 

Could be dodgy earth on the van

 

The trip goes maybe because some of the current is going back down the earth wire instead of the neutral.
Maybe the neutral and earth wires are swapped or shorted in the hookup, bypassing one side of the.balanced live and neutral circuits in the breaker. ..needs some current to flow to make an imbalance, any load will do it.

Disconnect, measure continuity of live neutral and earth then check for resistance between each of the wires.

Then remove the dead slug from the mains input socket.

 

Thanks both - really useful info. I'll run a continuity test on both the van and lead as well as checking for a short between each wire

 

My money would be on water ingress causing an intermittent fault!

 

If you did have an on board rcd in the van that would help to see whether it’s the lead or internal wiring that’s the problem. If the site has RCBO it might be a short circuit fault causing the tripping which wouldn’t trip an rcd!

 

I had a similar fault and I needed to bend out the little metal pieces on the hook up lead so they made better contact with the socket. Not sure if yours the same as mine as mine og German socket on van

 

That would do it!... Correction now ive seen the pic... that wouldnt do it!

 

I also had another issue later when my wife spilt a beer in the fridge vent! Took a while to dry out and forgive her for such extreme beer wastage

 

^this, as a possibilty. If the neutral in your van wiring is shorted to earth, this will reliably trip an RCD when you put a load on it. Get your meter out, unplug everything and check for shorts between pins.

 

That is EXACTLY like mine, I'll check. Its the original Westy Shucko connection, can be plugged in either way round just to confuse matters.

 

"Ex-Wife" after such spillage.....

 

Also give the connections in the van socket a little rough up so gets rid of any corrosion

 

Thanks again all - small update

Checked for shorts and continuity in the hook up lead - all good.

Checked the van and found an Earth to Neutral short, next step is to disconnect each circuit (socket and fridge) to see if I can isolate where it is (or indeed if it is inside the hook up connection itself). If I find the circuit it's on, I have no idea how I'm going to fix it without stripping the interior out as the wires are of course buried away...

 

I would trace back if you can and find out where e.g. a cable has got crushed into the metalwork by refitting a cabinet.. , if it isnt actually some bit of OG kit that has given up the ghost after nearly 50 years.

In the short term as your wiring is so simple, maybe disconnecting the internal wiring completely and wiring in a temporarily fitted two way extension lead to the mains input breaker and putting a mains plug on the fridge mains supply wire, that plugs into the extension socket might be a good idea.
Then you can sort out the issue later.

 

Cheers Mike, its not needed for a bit but I was going to use an extension lead to bypass.

I'm not sure how much of the interior was out when the van was cut up and welded, but my best guess is exactly that - a tapped cable has pinched through the insulation and is arcing out; most likely in the hardest to reach place possible.

Is there any fancy electricians gizmo that can detect how far down a cable a break might be? I have a cable sniffer that pulses a signal down a wire which you can then trace along to find out where it goes, or if there is a full break the signal fades out after this; I expect though that it wont be a full break so I don't think this will aid me at all.

 

If you have a wire with a short between two cores in it - in principle if you feed it with a signal, it will radiate magnetic fields up to the short and nothing beyond.

There are more fancy tools that tell you the distance to the short circuit by feeding in radio signals and measuring the time it takes for the signal to bounce off the short circuit - but they cost more than an afternoon with screwdriver taking out the fridge, looking behind it etc.

 

Thanks Mike - I'll have a go and report back!

 

You should be able to trace the cables easily enough - its a camper van, not the QE2......

Probably worth replacing the cable runs instead of repairing.