Rcd spur

[al1001]

Hi

I have fitted some new led outside lights
I have fitted a rcd spur off the ring main and rcd trips instantly iv tested all the cable and the rcd everything is fine.
I have even tried a new rcd unit and wiring the lights direct to the load side of the rcd and it still trips instantly.
I then put it down to the lights being faulty so I bought them back to my house and rigged them up with the same rcd unit and they worked perfectly

Has anyone ever know of the supply to the rcd causing it to trip??


Thanks

 

[EFLImpudence]

I have even tried a new rcd unit and wiring the lights direct to the load side of the rcd and it still trips instantly.

I'm always surprised that when safety devices operate people think the safety device is defective.
Not impossible but not the first port of call.
You said you had tested the RCD.

I then put it down to the lights being faulty so I bought them back to my house and rigged them up with the same rcd unit and they worked perfectly

Therefore the cable from RCD to light must be the problem.
That's why we do testing although you probably won't have the equipment.

Has anyone ever know of the supply to the rcd causing it to trip??

No, not possible.

 

[al1001]

Hi

I did a insulation resistance test on my fluke 1653b multifunction tester L to E, L to N AND N to E all with readings 500+ M ohms.
I also tired with the lights direct in to RCD
I am a qualified eletriction I have just never had anything like this and been pulling my hair with this and the only thing I could put it down to was something on the supply side but I have never know this effect a rcd just wanted to see if anyone els had ever had anthing like this

Thanks

 

[EFLImpudence]

Oh, sorry. I didn't realise.

There could be an leak to actual earth - not to the CPC.

 

[Taylortwocities]

I had a problem like this quite a few years ago and (forgive me) I cannot remember the maker of the RCD spur.
On the back os the RCD spur thre were actually two terminals that appeared to be the earth terminal.
One was the correct earth terminal and the other one (which i had used as the earth) was some other strange connection that was not mentioned in the unreadable "instructions" that were a 30th generation copy of a copy of a copy.

All I had to do was to move the earth to the other terminal and all was well. May be the same for you?

 

[Taylortwocities]

More…. waht make is the RCD spur, Greenbrook?
If so then there are some very similar stories to yours on the Screweyfix site
CLICK

 

[EFLImpudence]

Oh, Is it an active RCD and there is something wrong with the supply? I.e. no power.

 

[al1001]

Hi
Thanks for your replays
It's a CPN SU13P rcd unit I just noticed it has surge protection built in dont know if that could be something to do with
It's a passive rcd unit

Thanks

 

[al1001]

Hi
Sorry Replies not replay my iPad doing its own thing

There are 2 earth terminals I will look at that

Thanks

 

[kai]

Cheap far eastern junk that's why.

 

[flameport]

I did a insulation resistance test on my fluke 1653b multifunction tester L to E, L to N AND N to E all with readings 500+ M ohms.

Was that done with the E connected to the installation earth (via the ring circuit the RCD is connected to?)

 

[al1001]

No I just tested the new cable I installed with it disconnected at both ends

Thanks

 

[Adam_151]

No. You must leave the cpc connected when insulation testing. You are testing Live conductors to earth... not just to the CPC. So leave the earth connected to earth and just clip the lead from the tester on earth anywhere.

 

[ericmark]

We had an RCD socket 10 mA at work, and if you pressed the test button it would take out the 100 mA RCD feeding whole workshop so yes I have seen a RCD take out an RCD will guess the test resistor was to small.

I have also two identical RCD's mounted right next to each other feeding to fuse boxes old Wilex. It is common when resetting one RCD that the other one will trip so clearly some think on the input side can affect a RCD. Same with electric storms they can take out RCD even before it has started to rain. My RCD's are rather old fitted around 1992.

I have seen where the RCD tester showed the RCD to be A1, however it would trip, swapping to another RCD which also tested on the same meter to be A1 cured the problem. Not a clue why but I know it happened. I have seen where start from right resetting MCB's and RCD holds and start from left it trips. Again no idea why, may be just where it was on the wave form when MCB made.

In theroy non of that should happen but is practice it does.

 

[JohnW2]

We had an RCD socket 10 mA at work, and if you pressed the test button it would take out the 100 mA RCD feeding whole workshop so yes I have seen a RCD take out an RCD will guess the test resistor was to small.

For some reason which I don't understand, the test button on RCD sockets (and maybe also RCD FCUs) appears to create a L-E 'fault' for the test - as you say, in your case the resistor was presumably far lower than necessary to test a 10mA device.

The same problem does not arise with standalone RCDs, since their test buttons put a resistor across the RCD (from supply-side L to load side N), not from L to E.

Kind Regards, John