RCD's inline

[SimpleSimon]

Sonebody correct me if Im wrong please.
Scenario: On a local gypsy site, the plot consists of an.outbuilding that contains shower,water heater utilitys bench and some lights. Also.supplied is a 32a comnando socket used to power the main caravan.
The main CU in the outhouse is controlled by a 30mA main switch RCD.
From the comnando.socket a 6mm armoured flex runs from the commando plug straight into the caravans owm CU. Inside the caravan CU it also has its own RCD main switch 30mA. Si two RCD's inline.
The problem is that somewhere there is a fault that will trip either the RCD in the caravan or the RCD in the outhouse,or both.
Now the RCD only trips randomly and not related to the usage of anything, Ive never seen in trip in the three/four times ive been there. Today it has tripped and they cant swutch it back on (this is all over phone today). Ive put it down to a leak as the weather round our way is awful and previous times its only tripped whenever its rained.
So when they both trip one can be swuitched on straight away but one wont come on for a few hours. It always swaps over either one or the other, ciould anyone tell me why it takes time to come back on?

So if its tripping both RCDs the problem must be coming from inside the caravan right? Im trying to tell the tennants this but they say they think its from the commando socket. Im trying to tell them that if it was the socket the RCD in the caravan wouldnt trip, I am right in saying this?
Also just been on the phone to the guy RCD in outhouse keeps tripping and stays off. So i tell him to unplug the caravan from the comnando socket and hey presto the RCD comes back on, proof that its not the socket right?!!
I just need you guys to tell me whether what ive said is right ir wrong as im gettung paranoid. If the problem was on the supply cable to the caravan, it wouldnt trip the inside RCD, only the first one right??
Thanks for reading this long long start.

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[Octopus]

If you've got 2 identical RCD's in series its pot luck which one goes first. I guess a ramp test on both may give you the answer.

You get all the good jobs don't you?

 

[GLENNSPARK]

If you've got 2 identical RCD's in series its pot luck which one goes first. I guess a ramp test on both may give you the answer.

You get all the good jobs don't you?

chances are it will go for the RCD at the outhouse.....as it will be subject to accumilated earth leakage......

 

[mackers]

i shall correct u i think the term is TRAVELLERS!lol

 

[TPES]

I'd agree with you, as just said a ramp test would be good idea, ramp test within the caravan to see if there is anything in the caravan giving high earth enough leakage to trip the RCD..

 

[SPARTYKUS]

Depends! How quick they are each time. You really can't say.

 

[Deleted member 26818]

A fault downstream of the two RCDs will trip either or both.
A fault in between the two would only trip the upstream one. (This is why we place the RCD at the origin of the circuit in special locations.)
I would suggest that the next time the RCD/s trip, they switch off all the MCBs in the caravan, then reset the first RCD, then the second RCD, and if both reset, switch on each MCB untill the fault returns.
If they are able to identify the MCB where the fault occurs, then they should attempt to identify whether it is an appliance or a fault in the circuit causing the fault.
Disconnect or turn off each appliance, reset the MCB etc.

 

[alarm man]

as its a gypsy site..are you sure the cable is still there..:ihih:

 

[GLENNSPARK]

its happened before though hasn`t it......i heard of a gypsy site where the 'tennents' had ripped all the copper piping out of the utilities room.....hell they even pinched the boiler and sold that.......safe in the knowledge that the local authority would replace it and repair all the damage they had caused n all......all this because it would have 'breeched their human rights' if they didn't have a boiler......

 

[richy3333]

as its a gypsy site..are you sure the cable is still there..:ihih:

Beat me to the comment. Obvious but funny
Simon - Is your van still there when you get out the caravan?

 

[SimpleSimon]

A fault downstream of the two RCDs will trip either or both.
A fault in between the two would only trip the upstream one. (This is why we place the RCD at the origin of the circuit in special locations.)
I would suggest that the next time the RCD/s trip, they switch off all the MCBs in the caravan, then reset the first RCD, then the second RCD, and if both reset, switch on each MCB untill the fault returns.
If they are able to identify the MCB where the fault occurs, then they should attempt to identify whether it is an appliance or a fault in the circuit causing the fault.
Disconnect or turn off each appliance, reset the MCB etc.

This is what i was telling them.to.do over the phone. Told him turn off all MCBs turn on all RCDs and turn it on one by one. He said he did that and there was no power at all, nothing tripped but no power. RCD in caravan blown? Doubt it, think its just him. But when he turned caravan sockets on after a couple of seconds outhouse RCD went. There i think is the answer.
They think the fault is in between the RCDs but im telling them its not, its in the caravan.


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[GLENNSPARK]

This is what i was telling them.to.do over the phone. Told him turn off all MCBs turn on all RCDs and turn it on one by one. He said he did that and there was no power at all, nothing tripped but no power. RCD in caravan blown? Doubt it, think its just him. But when he turned caravan sockets on after a couple of seconds outhouse RCD went. There i think is the answer.
They think the fault is in between the RCDs but im telling them its not, its in the caravan.


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standard practice this.....just introduce circuits 1 at a time until the RCD lets go....then its a case of appliances on that circuit......

 

[SPARTYKUS]

Unless theres a N-E fault

 

[telectrix]

they need to know what is at fault so they know what to rob next.

 

[spiders803]

i would just tell them you have a nu mobile number.