Reverse Polarity showing after electrics tripped urgent help needed

[RustyRuss]

I people, I’m not familiar with the way that our Autotrail Apache 230v electrics are wired and wondered if any of you have experience of this particular problem.
All 230v electrical systems were working fine.
We put the water heater on on 230v only. We put the toaster on and then Kathryn put the microwave on, less than 30 secs later everything has gone off. No trips tripped at the EHU post, no trips tripped at the 230v side of consumer unit.

Symptoms now experienced:-
Reverse polarity now showing if all MCB’s are on, it goes off if the water heater MCB is switched off.
None of the 230v sockets appear to work, the fridge is off, the RCD will not trip when the test button is pressed.
The reverse polarity light stays on if the MCB for the water heater is on but the switch above it is off.
the red warning light on the right hand fuel selector switch is flashing for i guess non ignition of gas, even if only wanting to use electrics to heat water.

Everything is unplugged bar the fridge.

Has the heating element gone in the water heater Causing a short between neutral & earth? It’s a Truma unit. I haven’t got any electrical tools with me so can’t give any further info.

Please give me the benefit of your experience!!

Cheers!

Russ

 

[The Wino]

I'm by no means an expert but think it likely that the water heater MCB is shot. It try removing it and seeing what happens.

 

[Gaston aires]

I would try a process of elimination firstly removing the boiler fuse which sounds like the culprit. At least you will find out what’s causing it. You might have to switch the Ecoblock back on as well.
The fridge is on a separate circuit to all else.
Phil

 

[RustyRuss]

thanks for responses so far, where is the boiler fuse and how will removing it help?

 

[RustyRuss]

Definitely not the MCB, I’ve swapped wiring from one circuit to another and the other MCB is showing reverse polarity now.

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[RustyRuss]

Bump

 

[Speve]

Sounds very much like heating element goosed? have you tried unplugging hook up and lighting boiler on gas?

 

[Brianmor]

You have lost the supply to your motorhome, . You will need to find out where you are plugged in and check the fuses or MCBs there. The reason for my suggestions is that the test button doesn't work on your main RCD controlling your fusebaord, if that doesn't work then come back with what else you have found. Are you at home or on a site?

 

[pappajohn]

Definitely not the MCB, I’ve swapped wiring from one circuit to another and the other MCB is showing reverse polarity now.

If you mean you swapped water heater wiring to a different MCB it's definitely a fault on the water heater or associated wiiring..

 

[stevewagner]

Mains heating element I suspect

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[Brianmor]

All the time that the main RCD test switch doesn't work means you have no supply, it's pointless trying anything else till you have established you have a supply at your fuseboard.
Does the test trip work at the bollard, if it doesn't then you have tripped the supply neare the main source, talk to the site owners

 

[Speve]

All the time that the main RCD test switch doesn't work means you have no supply, it's pointless trying anything else till you have established you have a supply at your fuseboard.
Does the test trip work at the bollard, if it doesn't then you have tripped the supply neare the main source, talk to the site owners

I see your line of thought but he said:

No trips tripped at the EHU post, no trips tripped at the 230v side of consumer unit.

Has he still got mains supply in van??? From sound of it no and you are correct

 

[Dave Scadding]

The RCD probably won’t trip as it isn’t detecting power. Some sites have additional breakers for the post EHU as well as the breakers on the post. Get the warden to check supply. Or plug into a different post.

 

[TheBig1]

It is possible the hook up cable got damaged by overheating if the site bollard is faulty and didn't trip

One one site I visited somebody had jammed the trip switch with a match stick. Presumably because it kept tripping

 

[EML]

I'm not an electrician, but it sounds to me that your boiler has failed, and is shorting line/live and earth, not neutral and earth, as you suggested. Why? Because a reverse polarity tester isn't going to care about a neutral/earth short and, depending on your electrics setup, neutral is probably connected to earth somewhere anyway. But a reverse polarity tester might indicate a line to earth short as reverse polarity, depending on how it works, whether it does a proper test on neutral, and how neutral is wired.

An RCD should have tripped somewhere when this happened. Did you miss one?

Anyway: Stop testing. Disconnect the water heater completely, not just at the MCB. Call a qualified electrician.

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[Speve]

But a reverse polarity tester might indicate a line to earth short as reverse polarity, depending on how it works, whether it does a proper test on neutral, and how neutral is wired.

Autotrails have a reverse polarity light on the control unit built in as long as mains power is off nothing to worry about

 

[Donkster]

Just thought I’d mention it but did you check the polarity after hook up ? Was it already reversed

 

[Speve]

RustyRuss have you got yourself sorted yet? Hope so

 

[Red Sonja]

I would say that you were using too much power and have tripped the supply outside. Check your panel to see if you have power coming into the van. Or alternatively if you can try another bollard.

 

[gus-lopez]

Bump

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[RustyRuss]

Fixed it! Discovered by, going back to first principles, that the neutral wire (N) had come out of it’s terminal at the EHU Inlet socket, total coincidence that everything went off. Wiring looked like it had got quite hot and was close to going on fire! Anyway, taught me a lesson, always have a multimeter with you, (I borrowed one from a fellow camper, THANKS!) even one with missing probes and broken insulation (yes I fixed it for him with some self amalgamating tape) is better than nothing. I found that I only had 230v across live-earth (L-E), nothing across L-N (this should also be 230v) this caused the reverse polarity indication and meant that the RCD wouldn’t work, (it wasn’t detecting a differential across N-E). This is lack of experience with MOHO electrics and EHU’s and TT (technical term for the type of electrical supply system that should utilise an earth rod used on campsite electrical systems that this particular system doesn’t seem to use, illegal?) So I remade the terminals at the EHU inlet, rebuilt the consumer unit, put the water heater back together and put all the various bits of trim I’d removed back into place. What a PINTA! The upshot is that it now works, the hot water is on, the sockets work, the RCD operates, (should have realised that the reason it didn’t work was because it wasn’t detecting the differential between N and E), the fridge is on electric so the beer and wine are cooling again, SHMBO is feeling no guilt at all any longer for making everything irretrievably trip, the dogs have stopped cowering in the corner thinking it’s their fault that I’m being bad tempered, and the sun is in the sky, I have a lovely pale ale from the Llangefni Brewery in my hand and SHMBO is about to serve me some pasta and a beautiful sauce for dinner!

RESULT!

Cheers!

Russ

 

[Speve]

Well done glad you sorted it

 

[Captain Yoghurtpot]

Glad you are SAFE, and sorted and that your pasta was nice.
Quick question though.
Is that the standard of a Factory fitted EHU socket on your van?
If so, personally I think it is very poor.
But definitely glad you are both safe.

 

[EML]

Well done on getting everything running, but this doesn't explain why your polarity reversal indicator was on. If the neutral was disconnected then basically you've just put an on/off switch in the neutral wire, instead of line. The break is just a switch; there's no polarity reversal. 'Correct' polarity is 230V on L-E, ~0V on N-E, and reversal is the other way round. It's possible that the Autotrail indicator lights up to show a fault when it detects that line and neutral are both at 230, but that's not reversal.

You can get cheap Chinese mains testers (I think mine was about £16) that do correctly detect reversal, and show the voltages between all 3 pins on a socket - this would have spotted your problem immediately.

Note that RCDs don't work by "detecting a differential across N-E": they work by measuring 'residual current' using magnetics. If the current on line is different from the current on neutral then it opens. In your case, there was no current at all, because neutral wasn't connected, so no difference in current, so no reason to activate.

I would complain to Autotrail about your socket. It looks like there was a high-resistance connection on neutral before it disconnected completely, and the resistance caused the heating, with potential fire risk. The wire stripping is very amateurish. If you zoom in in you'll see that the live wire is exposed where the insulation has been stripped.

 

[RustyRuss]

I have to say I was a little shocked and stunned at the poor quality of the terminations in the EHU socket, however I have no idea who has been there before me, but I tend to to make bloody sure my terminations are nice and tight and that the conductors are properly secured in their terminals. HEY HO! Lesson learnt….

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[eddie]

We put the water heater on on 230v only. We put the toaster on and then Kathryn put the microwave on, less than 30 secs later everything has gone off. No trips tripped at the EHU post, no trips tripped at the 230v side of consumer unit.

Please give me the benefit of your experience!!

Cheers!

Russ

Try to remember your powering all this from an extension lead which is all a hook cable is

 

[autorouter]

the RCD operates, (should have realised that the reason it didn’t work was because it wasn’t detecting the differential between N and E),

The test button of the RCD tests the trip mechanism, not the earth. It feeds a small leakage current from the outgoing live to the incoming neutral. This current bypasses the outgoing neutral, so it is detected as missing by the trip mechanism. This test will work regardless of the state of the earth connection.