RCB Trips

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DanMcIntyre

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Hi All,

First of all, I'm not a qualified spark so please excuse any lack of understanding of terminology. I consider myself competent and safe with electrics though.

A couple of nights ago we started experiencing trips on one of the RCD's in our split load CU for no apparent reason. The RCD could be reset straight away without unplugging anything or isolating circuits. Later that night I noticed Northern Powergrid guys kicking about. Basically, our street is fed using 2 phase cables and a neutral along the tops of the terraced houses and the other phase was blowing fuses. Every time they tried a new fuse to try and isolate the fault, one of our RCD's tripped, but not the other. They fixed the fault (there was arcing between phase 2 and neutral in a junction box above our extension) and the RCD stayed on for the rest of the night. The weather was shocking at the time, and lashing down with rain.

The next day, our RCD tripped another 3 times, and then the day after (yesterday) the RCD tripped another 3 times, and it tripped while I was at work today. Could there still be an upstream fault causing 1 of the 2 RCDs to trip? It seems too much of a coincidence for a wiring fault or faulty appliance within my house downstream of the RCD to have developed at the same time as a supply issue.

Any pointers on where to start troubleshooting are appreciated. I can borrow an insulation & impedance tester from work if need be but I don't particularly want to start dismantling the wiring unless I have to. I doubt the wiring inside the house all of a sudden went faulty with no tampering or alterations. 

Cheers.

 
Sorry but for this one you need to know what you’re doing and how to test in a logical manner. I very much doubt you’ll have the required test equipment.

I’ll cut to the chase, employ a reputable electrician.

 
May be a coincident with the mains problem  ...I was thinking about where you said the rain was bucketing down ....is there anything outside that may have filled with water  perhaps.  

Otherwise  do as the guys have said , get the RCD tested for tripping below it's settings . 

 
Momentary mains problems "may" cause older RCD's to trip.  i.e.   I have seen it personally with heavy construction/destruction equipment starting up 2 doors up on the same phase .  Never understood why so don't ask me !! 

Rain (and wet spiders and damp dust) in outside light fittings or outbuildings can also cause it.   For now have a good walk around looking for anything amiss (note I said LOOK not FEEL !!)

If something is amiss, or if not but it's still happening tomorrow , then getting an electrician to investigate it will save a lot of wasted thought/effort.

 
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