Discuss RCD tripping even with all switches and bulbs removed. in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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Hello all. A customer replaced a dimmer on his lighting circuit, ever since then the RCD keeps tripping and he called me. I have now removed ALL switches (one at a time) and light bulbs however it is still tripping. Using a Wander lead I got readings from the L, N, and E from the CU to the ceiling roses. At one point I got a reading from the ceiling L to an L on switch line but the L was removed from the ceiling rose at that point, so somehow it was connected. I checked it again the following day (due to time restraints) and there was now no reading. I will be looking in the loft on Monday to find the lighting cable from the CU and go from there (loft was chockablock at the time and customer is clearing for me for Monday) to see if any pressure is being put on the lighting circuit cable but apart from that I am stuck and feel like a bit of an idiot, can anyone help?
 
I think the best thing is to do a thorough test on the cabling ir bring the main one to do, does the rcd trip instantly the mcb is switched on or is it when a specific switch is pressed, could be a number of things but I would be looking for other things like pictures recently put up and all that. I find that customers tend to forget this sort of thing. Also remove the load from the mcb and then try the rcd again then you can see if its the load or the rcd
 
Just to comment on my own post, I will try an R1+R2 on Monday. Some of the ceiling roses made up from chock blocks are part of the wall lights but I have only checked one of these, continuity also fine. Also, I should check the on-suite bathroom extractor fan. Some of the lights are down lights, should I remove and check all those connections? Funny thing is he never had problems before only since he replaced the dimmer?! I have tried another lighting circuit in the MCB and it works fine.
 
Yes the MCB trips instantly, RCD and MCB work when another lighting circuit is connected, good question about new pictures i've texted my customer now. I will try an IR Monday.
 
Customer just gave me this info: At first dimmer blew RCD, dimmer was changed and worked and all was fine for a few hours then just blew RCD again. Any further advice..?
 
was there a dimmer there before or did customer fit one instead of standard switch, could be worth changing dimmer to standard switch just to eliminate faulty dimmer before jumping into all the usual testing
 
Did you not see the almost identical thread last week?
Something like 10 pages of everybody telling some idiot to do IR tests but he wouldnt listen and gave himself a right showing up.
Anyway here it is for the second time on this thread,....................................... DO IR TESTS.
Only then can anybody help you without guessing.

Boydy
 
Did you not see the almost identical thread last week?
Something like 10 pages of everybody telling some idiot to do IR tests but he wouldnt listen and gave himself a right showing up.
Anyway here it is for the second time on this thread,....................................... DO IR TESTS.
Only then can anybody help you without guessing.

Quite. The OP is wasting his time and everyone else's if he hasn't started with IR testing. Continuity is a waste of time at this stage. As a starting point, L+N to E with all lamps in and switches on will do. Then hunt it down to a specific part of the circuit.
 
quick simple job replace the dimmer with a switch... if this cures it then its possible your dimmers are failing due to the job they are doing are you dimming LED lamps ? As others have already said why come on here asking whats wrong when you haven't even done standard testing procedures an IR test will show any insulation breakdown etc that can't be seen otherwise... if you dont possess these basic of basic testing equipment then dont bother us as you are trying to achieve something without the correct equipment.
 
the reason I earlier said change switch before IR testing is that the op said it had started after the customer had replaced a dimmer, simply opening up the switch to replace with new gives a quick visual inspection and the fault could be staring him in the face without having to use any test gear
 
The idea here is to get job done asap to impress first thing id do given the customers story is take the dimmer out and try a switch..... if this dont cure it then start thinking about testing, it only takes 2mins to swap the dimmer but could save you alot of time if because of the circuit design the dimmer has failed as has the one before it.
 
Hello Captainkev, thanks for your support, RCD still trips with ALL switches and bulbs removed leaving all wring exposed! I was thinking possible pressure on cabling in loft. Checking that on Monday.

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Hello darkwood, thanks for your support, RCD still trips with ALL switches and bulbs removed leaving all wring exposed! I was thinking possible pressure on cabling in loft. Checking that on Monday.
 
Hello Boydy, thanks for your support, RCD still trips with ALL switches and bulbs removed leaving all wring exposed! I was thinking possible pressure on cabling in loft. Checking that on Monday.

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Hello LittleHelper, thanks for your support, RCD still trips with ALL switches and bulbs removed leaving all wring exposed! I was thinking possible pressure on cabling in loft. Checking that on Monday.
 
Hello HandySparks, thanks for your support, RCD still trips with ALL switches and bulbs removed leaving all wring exposed! I was thinking possible pressure on cabling in loft. Checking that on Monday.

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Hello Chrish_1977, thanks for your support, RCD still trips with ALL switches and bulbs removed leaving all wring exposed! I was thinking possible pressure on cabling in loft. Checking that on Monday.
 
Hello Little Helper, RCD works with another lighting circuit put in it, dimmer was there in the first instance, new one worked for a few hours then tripped, but RCD still trips with all switches removed from pattress' and bulbs out. I'm in the loft on Monday to find dimmer cabling to see if any faults/damage etc.
 
Hello Darkwood, thanks for your concern but I do possess all the correct equipment to practice as registered domestic electrician. Using a Wander lead I got readings from the L, N, and E from the CU to the ceiling roses. At one point I got a reading from the ceiling L to an L/com on dimmer switch line but the L was removed from the ceiling rose at that point, so somehow it was connected. However, I checked it again the following day (due to time restraints at the time from the customer) and there was now no reading. I'm in the loft on Monday to see if any faults/damage to dimmer cable. What do you think?!
 
Ooh, I got a reading form the CU to the dimmer L/com, and the L on the ceiling rose was removed...?!

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Ooh, using a wander lead I got a reading form the CU L to the dimmer L/com, and the L on the ceiling rose was removed...?!
 

Reply to RCD tripping even with all switches and bulbs removed. in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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