# EHU trips mains ELCB



## alexfernie (Jan 21, 2011)

Hi,

Long time lurker, first post. Been hiring MHs for the past few years but have recently bought a 1996 Elddis Autostratus/Peugeot Boxer combo.

Problem: When I plug it into the house mains it trips the house ELCB. Nothing is plugged into sockets etc in MH. The MH fuse panel has inlet RCD and 2 RCD's - RCD 1 does Fridge/pump/charger; RCD 2 does 13A sockets, and presumably the carver fanmaster & carver heater when on 240v. 

So... When RCD 2 is off (i.e 13A outlets/carver units) is off, house ELCB doesn't trip. So presumably charger/fridge/pump aren't the problem, i.e. RCD 1 and its associated applicances don't trip ELCB. As soon as I switch on RCD2 - with no load on and all applicances off, the ELCB in the house trips.

I've checked earth to chassis connection and all good there. I've taken all the carver control panels & 13A sockets off the wall and checked connections & phase. All good there. Fuses for all carver units perfect.

So it's down to the carver fanmaster or the water heater, I think. Haven't been able to test water heater due to the cold weather. 

What have I missed? Obviously need to check the cascade 2, but what should I look out for? 

On a possibly related note, there is a sustained whining noise when I switch the fanmaster to Electric 

Any info/experience of same will cut trouble shooting time.

Thanks in advance, Alex.


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## cabby (May 14, 2005)

I hope that before you did all that, you did check out the wiring on the 13amp sockets in the van. also have you tried it in another plug in the house.

cabby


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## clodhopper2006 (Aug 13, 2006)

Hi Alex and welcome to the forum. Just to clear up some terminology issues first so that we avoid confusion.

Firstly the device you have in your house that trips is probably not an ELCB (Earth Leakage Circuit Breaker), it is more likely to be an RCD (Residual Current Device) that supercedes the ELCB.

Now in your van you will most likely have a mains switch/RCD that monitors earth leakage and a number of MCB's (Minature Circuit Breakers) that handle overcurrent.

As I understand your post your house RCD trips when the MCB for the Carver unit is switched on. I think you'll find you have some cold weather condensation in that area causing a slight earth leakage. All you need to do is get some heating into this area overnight, maybe use a fan heater and get the van thoroughly warm and I think you'll find in the morning your problem will have gone.


As a matter of technical interest the RCD came into use as it monitors current leakage to earth in the whole circuit. This is much safer than the ELCB that monitored voltage and could not detect a neutral/earth fault.


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## clive1821 (Mar 27, 2010)

I would be looking at the water heater first as the cause of the issue, if its a electric element in the heater my money would be on that, easy to check buy disconnecting it and then its a process of elimination, circuit breaker 2 seems to point correctly to the circuit at fault... if you have a insulation tester it make life a lot easyer... best of luck...


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## trevorf (May 16, 2005)

I agree with the last post, likely cause is a short circuit heating element in the water heater. Check with multimeter for short circuit between live and neutral or disconnect at the element itself.



Trevor


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## UncleNorm (May 1, 2005)

And where have I heard or read the advice that the motorhome RCD should be in the OFF position BEFORE the mains hook-up is inserted? :?: 


Thanks Clod for your detailed clarification of terminology. :wink:


How remiss of me... a warm welcome to MotorhomeFacts to Alex. I hope you stay with us a while as there is a huge depth of experience and expertise available here. :wink:


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## sallytrafic (Jan 17, 2006)

trevorf said:


> I agree with the last post, likely cause is a short circuit heating element in the water heater. Check with multimeter for short circuit between live and neutral or disconnect at the element itself.
> 
> Trevor


If its the rcd that has tripped more likely to be a live (or neutral) to earth short (or partial short)


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## alexfernie (Jan 21, 2011)

*EHU trips mains RCBO*

Hi thank you all for your welcomes, clarifications and advice. Will check the water heater when she comes back from having a mechanical service and let you know how I got on.
Best,
Alex.


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