Wall Lights and Problem with RCD Ask questions and find answers to many subjects relating to electrics and electrical work

[holmedwa04]

Hi,

Recently I have helped install some wall lights, these are connected to a secondary consumer unit that powers everything related to the garden. We have used armoured cable to ensure that it cant be damaged and where the lights have been installed we have used the drainage pipe used on sinks to allow the fitting to be taken out if necesary. Here is a link to the lights we are using:

http://www.screwfix.com/app/sfd/cat/pro ... 1&id=32719

So here comes our problem, when you switch the lights on they work fine, but on switching them off the RCD on the secondary consumer unit trips. This doesn't always happen and so we are not sure why. We have checked that all fittings are dry and connections in them are correct.

If the lights are left on for a while it doesn't seem to trip the RCD, it only trips when they are turned on for a short while. It is as if they are creating some sort of a surge when they are switched off.

I am sure there is a simple way of fixing this, so please, if anyone knows a cure for this problem reply ASAP! :(

[sparx]

Hi I know the brick lights you are using and they are prone to damp problems due to condensation, which dries out after a while, don't know why they don't trip on switching on but a hair drier followed by some silica jel sachets cured our last set!
regards SPARX

[holmedwa04]

Hi,

Thanks for your reply, but on installing them we used a hair drier to ensure that they were dry before putting the glass plate on front. I have looked into the problem a bit more and it seems that because they are 12V they have a transformer, this has a capacitor in it and when switching them off it discharges, creating an inbalance on the neutral and switching the RCD.

We have come up with another solution, which involves wiring it to an MCB on the unprotected side of the RCD in the primary consumer unit, but this means more SWA cable! and other things like water proof junction boxs. Apparently it can be solved using resistors or something, but I wouldn't know where to start.

[holmedwa04]

Hi again, we have decided to wire the wall lights into the main consumer unit on the side unprotected by the RCD.

We have done this, but apparently, even now the RCD in the secondary consumer unit is still tripping when the lights are switched off, even though it is not connected to it.

We have decided that the RCD in the secondary consumer unit must be too sensitive, so we are going to replace it, and if it proves to be too sensitive, get a refund for it!

So hopefully, we shouldn't have any problems when it is replaced, thanks for everyones help, much appriciated.

[holmedwa04]

Change of plan, rather than buy a new RCD, we have tried fitting a supression unit out of an old washing machine, this seems to have done the trick and everything is working fine now! Thanks for everyones help and suggestions.