Hi
In my previous van I used a B&Q stand alone RCD as my electrics protection. In my new van I have installed a Screwfix supplied consumer unit that has an RCD as well as MCB's. However, the RCD keeps tripping out under any more than minimal load. I got a replacement RCD but still got the problem. I've checked all the wiring coming into the van using a Maplin tester (reversed polarity etc. Anyway to enable me to use the van I've put my B&Q RCD in the wiring upstream of the consumer unit and bypassed the consumer unit RCD. Everything works fine, but only temporary whilst I get the consumer unit RCD sorted.
Where I need help. The consumer unit RCD has four terminals. The live input and output, and 2 neutrals. One neutral comes wired to the neutral terminal block and the other is not wired. Not sure what the latter is for, and not mentioned in the brief instructions, so I've not used it. The live out is bus bared to the MCB's. I haven't earthed the consumer unit to the van yet, but will be. Can't see why the latter could be causing the problem because the wiring is earthed via the mains input wiring. Any help would be appreciated.
Maurice
Is the RCD is installed in the 230 V system of your van?
DutchAussie
2014 Renault Trafic X83 LWB Van
If you haven't got it sorted yet, I think the problem is the incoming neutral from the supply should be connected to the "unwired" neutral terminal on your RCD. The other RCD neutral terminal connects to the neutral terminal block as you described.
The RCD works by comparing the current flowing in the live and neutral. In normal operation these are equal, but in a fault scenario some of the current flows to earth and therefore does not return via the neutral. The RCD detects the inbalance and disconnects the supply (trips).
At the moment, the neutral isn't going through the RCD so it will always detect an inbalance and trip with even a small load.
Final thing, you MUST earth the van chassis. Connect the mains earth from the consumer unit earth point to to an unpainted point on tthe van's chassis. This is to prevent the bodywork of the van becoming live in the event of a live to metalwork fault. Whilst you're in the van, you would be ok - but the moment you (or someone else) touches the van and the ground outside (perhaps wearing flip-flops in a wet grassy field) a leathal shock could be received.
Hi. For some reason I've only just been notified of your post of 13/03/14. Anway thanks for the info your were quite right in your diagnosis. Maurice