Motorhome Tripping Main RCD Unit in House (1 Viewer)

[zac]

Well it appears as though my motorhome is intermittently tripping the rcd unit in the house since having the extra wiring installed on the towbar.

I called out an electrician to get everything checked and he has confirmed that the lead coming from the motorhome is reading 0.197ohms which apparently is not correct as should be in the hundreds. Now have to take the thing back to where it was fitted to see where it is shorting, i think what is happening is that when it is charging the leisure batteries it is ok but when it then flips over to the cab battery it is then shorting the rcd in the house.

Absolute pain in the back side as we are going away in 2 weeks so i am just praying he finds the issue tomorrow when i am taking it back else i will have to disconnect what he has done.

 

[Lenny HB]

No way can the tow bar wiring effect it that is all on the 12v side.
First try a different hook up lead , then if it still does it switch off or disconnect everything powered by mains in the van. Then if it doesn't trip turn on or reconnect each item one at a time, hopefully you will find what is tripping it.

 

[pappajohn]

12v Output from the charger is in no way directly linked to 230v from the house.
12v in the van CANNOT trip the 230v breaker in the house.
It would blow a 12v fuse in the van.
More likely your charger is faulty and either overloading the breaker or has an earth fault.

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[zac]

No way can the tow bar wiring effect it that is all on the 12v side.
First try a different hook up lead , then if it still does it switch off or disconnect everything powered by mains in the van. Then if it doesn't trip turn on or reconnect each item one at a time, hopefully you will find what is tripping it.

I can only say what i am experiencing and had testsed, when i got home from having it done and plugged in the mains lead it tripped the rcd in the house. Since then it has tripped every day since getting back, now i have turned it off and no tripping. Electrician tested with the motorhome plugged in and found a fault. Electrician also checked the actual mains lead and this is ok so issue is with motorhome

 

[pappajohn]

How did you check the mains lead ?

 

[zac]

How did you check the mains lead ?

Electrician checked it using large device with lots of buttons on it

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[pappajohn]

Your kitchen SHOULD be on its own breaker so if plugged in there try a different room or upstairs which should also be on its own breaker..
It could be a faulty/weak breaker.

 

[zac]

I was told that the reading from the plug should be in the hundreds or something

 

[zac]

Your kitchen SHOULD be on its own breaker so if plugged in there try a different room or upstairs which should also be on its own breaker..
It could be a faulty breaker.

The rcd that is blowing controls the garage and up/down sockets but the individual breakers are ok, it is the main rcd that is blowing which cuts out the 3 above

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[zac]

forgot to add the electrician checked the breakers first,the kitchn sockets are on the same side as the garage and up/down sockets.

The main reason why i think it is the wiring that has just been done as it started happen when i got back and tripped as soon as i plugged in the motorhome.

 

[pappajohn]

The rcd that is blowing controls the garage and up/down sockets but the individual breakers are ok, it is the main rcd that is blowing which cuts out the 3 above

That's an earth fault...live to earth or neutral.

As it does work at times its an intermittent fault and won't show on any test if the fault isn't there at the time.

The main RCD is rated far higher than all other MCBs combined as far as overload is concerned...probably 63amp.
The RCD is designed to trip if its an earth fault...MCBs trip on overload only.

 

[zac]

That's an earth fault.
The main RCD is rated far higher than all other MCBs combined as far as overload is concerned...probably 63amp.
The RCD is designed to trip if its an earth fault...MCBs trip on overload only.

But it only trips when the motorhome is plugged in and when it trips i can reset it then it wont trip for another day or so.

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[pappajohn]

Turn off your charger then plug in some 230v stuff in the van.....if all ok then your chargers faulty.
Hope it's not Mickey and his family eating your vans 230v wiring.

 

[pappajohn]

But it only trips when the motorhome is plugged in and when it trips i can reset it then it wont trip for another day or so.

Intermittent earth fault...as I said, hope it's not Mickey.

 

[Gizmouk]

I would suggest that whoever has installed the towbar has inadvertently caused a live to earth or neutral to earth fault. Maybe drilled a hole where it ought not to be, or caught / crimped a mains cable somewhere. Any decent electrician / auto electrician should be able to find the fault quickly through stage fault finding - i.e working through the mains wiring (motorhomes are very simple, so won't take long !)

Live - earth or neutral - earth should be in 100s megohms, normally higher than the test meter can read ( > 999.9Mohms)

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[zac]

Turn off your charger then plug in some 230v stuff in the van.....if all ok then your chargers faulty.
Hope it's not Mickey and his family eating your vans 230v wiring.

Not sure i follow as if i unplug the mains charger then the 230v inside the van wont work at all.

When the lead is plugged in there is nothing on in the van at all, not even the control panel. But it did trip the rcd.

 

[zac]

Intermittent earth fault...as I said, hope it's not Mickey.

No mice where we are as outside the house and the cats would def have them

 

[zac]

just to clarify all that was added to the motorhome was 2 leads (i think) running from the back of the motorhome connected to pin10 (1 of them) not sure about the other and then going directly to the cab battery under the passengers foot well. No idea how this trips the rcd in the house but the first time i plugged it in when i got back it tripped. It has also tripped multiple times since then and now i have unplugged it it no longer trips.

All the wiring for the towbar was already in place and this added to allow me to charge the battery on the trailer whilst towing.

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[pappajohn]

Not sure i follow as if i unplug the mains charger then the 230v inside the van wont work at all.

When the lead is plugged in there is nothing on in the van at all, not even the control panel. But it did trip the rcd.

Yes it will all still work.
The charger is only part of the 230v circuit as is the fridge.
By turning off the charger at the vans 230v breakers or on the charger itself that takes it out of circuit but all other sockets and fridge still work.
Just like unplugging your kettle in the house.

Even though nothing is turned on or plugged in the charger still is.....unless you turn it off at charger or its 230v breaker.
It ALWAYS runs in the background if its on hook up.

 

[tonyidle]

The mains lead from your house connects to the input socket on the van. From there it goes to the van RCD and from the output of the RCD it is connected to a number of breakers (MCBs) that serve individual services in the van. If the mains lead is OK then either the wiring from the van input socket to the van RCD is damaged or one of the circuits fed by the RCD is faulty. The next step is to find out which.

 

[zac]

Yes it will all still work.
The charger is only part of the 230v circuit as is the fridge.
By turning off the charger at the vans 230v breakers or on the charger itself that takes it out of circuit but all other sockets and fridge still work.
Just like unplugging your kettle in the house.

Even though nothing is turned on or plugged in the charger still is.....unless you turn it off at charger or its 230v breaker.
It ALWAYS runs in the background if its on hook up.

Ah I see what you mean now, I am taking it back tomorrow to see if he can trace the fault, if it comes to it I will just remove the fuse from the wiring he has put in and just do with it out. I only have one trip left then the MH is going but I certainly would not want to let it go without them knowing if there is a fault. As this only happened when this extra wiring was installed that it my first port of call. Of course I will check that if when it comes back it is still blowing but I am hoping it won't and he will find the cause. He was under the van for a long time with a soldering iron at one point.

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[pappajohn]

PLEASE let us know the outcome.
Really frustrating when nothing is posted after a fix.
It can/will always help others with a similar problem in future.

 

[pyro]

Some good comments here.

My advice (and I agree that the 12V circuit should be completely isolated from the mains, but the earth is common, and there could be problems on the input side of any transformer in the charger):-

• Plug the lead in to the house (but not the van).If the house RCD trips, then the fault lies in the EHU lead
• Then turn OFF all the mains breakers in the van.
• Connect the EHU lead to the van
• If the house RCD trips, then the fault lies in the wiring between the EHU socket on the van and the van's mains consumer unit)
• Make sure all appliances (including charger, fridge, etc) are OFF,
• switch OFF all consumer unit RCDs
• Then reinstate the RCDs on the consumer unit, one at a time.
• This will help isolate the fault, to see if it is caused by any single appliance (e.g. charger, fridge, water heater, etc)

I suspect that the addition of the tow socket has resulted in the disconnection of an earth somewhere, or damage to another cable, resulting in an intermittent fault

Not a fan of soldered connections on vehicles, vibration and work hardening and all that

 

[zac]

PLEASE let us know the outcome.
Really frustrating when nothing is posted after a fix.
It can/will always help others with a similar problem in future.

Well now i am completely confused, took the MH back to get it checked and after about 30mins the guy says he cant find an issue. He also then tested the mains lead that was plugged into the MH and this reads normal i.e. 111m ohmes (the reading the house electrician was abnormal i.e. 0.197m ohmes).
So i get home expecting it to then trip the rcd again and now it works ok (No Tripping). So i am now at a loss as things do not just fix themselves

This is not a lot of help to others as i dont know why now it is not tripping, everything is exactly the same (same leads/points/plugs etc)

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[Vanman]

Sounds like an Intermittent fault, it'll probably start again when fridge kicks in or heater comes on

 

[zac]

Sounds like an Intermittent fault, it'll probably start again when fridge kicks in or heater comes on

Nothing is on in the MH as it is parked up outside the house just to keep the batteries topped up same as before.

 

[Vanman]

Sounds like you're missing it already Could be charger related, maybe when a battery starts to need it after the run out has topped them up.

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[zac]

Sounds like you're missing it already Could be charger related, maybe when a battery starts to need it after the run out has topped them up.

The first time it tripped was when i plugged it into the mains after having the extra wires installed for the towbar.This time it didnt trip when plugging it in which leads me to believe it is now ok although time will of course tell. I will give it a few days as if it is going to go it will go soon.

 

[hilldweller]

I will give it a few days as if it is going to go it will go soon.

Maybe, maybe not. If a bit of bare wire is shorting occasionally, like at a certain temperature when it moves a bit, it may have been disturbed and may come back tomorrow or next year.

A good question is, why does the house trip and not the van ? Is it just speed ?

 

[zac]

Maybe, maybe not. If a bit of bare wire is shorting occasionally, like at a certain temperature when it moves a bit, it may have been disturbed and may come back tomorrow or next year.

A good question is, why does the house trip and not the van ? Is it just speed ?

No idea, i have had both checked now and the house is ok and so now is the van. I dont like not knowing what has fixed something but time will tell as is may not be fixed just lying in wait.

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