Mysterious electrical fault

[Robert Clark]

Hi Guys

We had been living in our van full time from April to November whilst we had building works carried out at home.

These works included a new consumer unit and partial re wire.

Since the new consumer unit was fitted in November the RCD has been tripping regularly and it appears that the culprit is our vans inverter / charger.

As we never had any problems prior to the new consumer unit being fitted at the end of November, it seems a strange coincidence that the charger has suddenly developed a fault.

Looking at the offending RCD in the consumer unit (there are two) the rated trip current of 30mA is the same as on the old unit.

Any thoughts would be appreciated

Thanks

 

[sonar]

The company that fitted all the electrics should be ask to come back and have another test.
and see if all is ok .

if it is then start to look at other items ie your inverter.

 

[RowleyBirkinQC]

Is the charger/inverter a single unit? Are you able to turn off the inverter whilst the charger is active?

Stupid question, is it worth testing with a different EHU cable and power point to see if the same behaviour persists at the Consumer Unit end?

 

[Trevor Wbm]

Wild Guess ..... the newer consumer units are more sensitive than the older ones. If it passes all the tests but the MoHo is what's tripping it, I would look carefully at the earthing in the 240v set up on the van. It should be within the scope of yer average DIY'er to isolate or disconnect the equipment to see if a specific piece of kit is what's doing it. You might start with items on automatic switches like 'fridges and heater thermostats. ** Edit ... ah, you've done that, if you're happy it's the inverter see below but ask a proffessional**

Getting into areas where you definitely need a sparky and shouldn't take my word for it, breakers come in different flavours, referred to as B-curve, C and D-curve, apparently about the amount of surge current they will tolerate. (I had to change some out on circuits supporting 2Kw heaters on the bar patio). B-Curve is the standard for domestic installs.

 

[Robert Clark]

Is the charger/inverter a single unit? Are you able to turn off the inverter whilst the charger is active?

Stupid question, is it worth testing with a different EHU cable and power point to see if the same behaviour persists at the Consumer Unit end?

It’s a combined charger inverter.
I already swapped the EHU cable and plugged into a different socket

Now running the heating on electric to rule that out

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[andy63]

I'm not sure how these inverter chargers are set up but you have that plugged in to the house mains I presume to run the charger side..not the inverter..
Can you isolate the unit anf have an insulation test done on that side of the unit.. to see what fault is on it..
Andy

 

[Minxy]

We had a VERY sensitive consumer unit when we first moved into our place, it drove us nuts, sometimes a bulb blowing would cause it to shut all the electrics off, sometimes the fridge coming on ... in the end we got it replaced with a different model and all has been well ever since so it could be the unit itself.

 

[Rob Turner]

You say that you have plugged the EHU into a different socket.
Was that socket on the same ring main?
As you have had a new board fitted you’d have been better off with RCBOs than the two RCDs you have. Easier for fault finding and not as inconvenient when one trips as it only takes that circuit and not the bank that is protected by the RCD, your sparky should have consulted you regarding that.

 

[funflair]

Hi Robert Clark

We had a strange one with a friends Concorde but that is Mastervolt, it kept tripping the site and again we eventuallu nailed that down to the inverter charger, turned it off and back on and all was OK, I wondered about some residual current/charge in the inverter but dont even know if that is possible.

 

[Robert Clark]

You say that you have plugged the EHU into a different socket.
Was that socket on the same ring main?
As you have had a new board fitted you’d have been better off with RCBOs than the two RCDs you have. Easier for fault finding and not as inconvenient when one trips as it only takes that circuit and not the bank that is protected by the RCD, your sparky should have consulted you regarding that.

I agree about the RCBO’s being a better option, especially as most of the original wiring in the house was remaining and might have potentially more faults compared with a totally new installation.

I’m wondering if we could convert our new consumer unit to RCBO’s or would we need a whole new consumer unit ?

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[eurajohn]

You mention that it is the RCD that trips not the MCB are you aware there are different types of RCD, most common in houses are type A and type AC, so is your van plugged into a socket from an AC RCD? Could be your problem.

 

[Robert Clark]

Hi Robert Clark

We had a strange one with a friends Concorde but that is Mastervolt, it kept tripping the site and again we eventuallu nailed that down to the inverter charger, turned it off and back on and all was OK, I wondered about some residual current/charge in the inverter but dont even know if that is possible.

It’s off at the moment Martin and all appears to be ok with the RCD. The heating is on for frost protection which is my main concern.

Will try turning it back on tomorrow and see what happens.

 

[ctc]

RCD's are far more unreliable than many realise and get it tested by a different company. Don't believe the installer.

 

[Rob Turner]

RCBOs can replace MCBs, the only difference is they are a bit longer so take up more room in the CU, obviously cable ratings etc would need to be checked but your spark can sort that.

 

[Robert Clark]

You mention that it is the RCD that trips not the MCB are you aware there are different types of RCD, most common in houses are type A and type AC, so is your van plugged into a socket from an AC RCD? Could be your problem.

Here is a pic of the RCD can you see what type it is?

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[Robert Clark]

RCD's are far more unreliable than many realise and get it tested by a different company. Don't believe the installer.

RCBOs can replace MCBs, the only difference is they are a bit longer so take up more room in the CU, obviously cable ratings etc would need to be checked but your spark can sort that.

I think I’ll end up getting a different electrician to take a look and advise on replacing / upgrading the consumer unit.

We’ve had a few other funny issues with the wiring and I’m not confident in this guys competence

 

[eurajohn]

The picture shows a type A, which is what I would have thought you need, think the second opinion approach might be best.

 

[Robert Clark]

Update

A few days ago I turned off most of the vans circuit breakers. Then turned the inverter charger back on.

Broken Link Removed

Since then the house RCD hasn’t tripped, which suggests any minor current leakage is not a fault on the inverter itself.

Over the coming days I’ll start turning the circuit breakers back on and see what happens.

I’ve also asked our builders electrician to pop in to look at potential solutions.

 

[berni109]

Robert Clark you just need to start from a known position with everything switched off at the breakers in the van and the house then gradually switch each mcb back on . House first which should be good (to have passed the installation tests) then with hook up cable connected but not to van in case it has a fault.
Assuming both sides of the consumer unit are ok with the hookup connect it to van and then progressively switch the Van's mcbs and power up the devices they protect. You could do this 1 van circuit at a time to prove there is no interaction/connection between van circuits .
If anything trips the house consumer unit go back a step and connect hookup to other side of cu. Most unlikely that both rcd s are faulty.
(Not trying to teach granny to such eggs just suggesting a logical approach HTH)