RCD tripping has anybody any Ideas?

[Rikmac]

Been to a customers home today,Reported fault was when he turned the kitchen light off the RCD tripped
Problem is its a split-load board and the lights are not on RCD side
The light switch in question controls 3 pelmet lights
wired feed+N to switch and twin out
I couldnt get this fault to happen whilst i was there and everything worked fine TBH thought it was a bit of customer confusion and it was probally an appliance so tested the RCD for tripping times and ramp and everything checked out ...Tripped at 25mA
The board is Protec

The customer rang me back tonight and said that its doing it again and as the switch is at the side of the fuseboard he could see the RCD tripping as he turned the light off

If anybodys come across this or has any Ideas Id love to hear them

 

[Strima]

Neutral on the wrong bar? What type of pelmet lights? LED, ELV etc?

 

[Rikmac]

Thanks for reply.. No neutral is on RCD bar ....It wouldnt work at all if it wasnt ...its tripping when he turns it off
T5 Pelmets

 

[Octopus]

Any recent changes to the installation?

 

[Rikmac]

No last thing was a boiler fitted 4 years ago its been working fine till a couple of weeks ago

 

[johnduffell]

Neutral to earth fault on the rcd protected side? Check items that aren't always plugged in or are behind dp switches

 

[Rikmac]

although he has changed one of the pelmet lights but not until the problem started

 

[Wilko]

I have once seen a light switch trip an RCD a bit like that. Light circuit was florry and RCD was on it and wired correctly etc. I replaced the 10A light switch and the problem was gone. Don't ask me what was going on, I may've fixed it by accident.

 

[Octopus]

^^ could be a fault on the non protected side and a fault on the protected side ....

 

[Rikmac]

Neutral to earth fault on the rcd protected side? Check items that aren't always plugged in or are behind dp switches

Hmmm you may be on to something ...but if NtoE fault on RCD side the RCD should trip because of the inbalance not because of light circuit thats not on RCD side??

 

[Rikmac]

I have once seen a light switch trip an RCD a bit like that. Light circuit was florry and RCD was on it and wired correctly etc. I replaced the 10A light switch and the problem was gone. Don't ask me what was going on, I may've fixed it by accident.

Yes I think im in that Unknown zone...Neutrals are in connecters and the live is bridged to feed the main light in the kitchen .....main light works fine and doesnt trip the RCD

 

[Rikmac]

^^ could be a fault on the non protected side and a fault on the protected side ....

Yes im thinking there could be more than one fault but cannot think of a situation that this would happen
My gut is telling me its something to do with the Protec RCD but im not a fan of this product so it may be just me been prejudiced

 

[PEG]

These situations occur,and you need to start at the beginning.
You may have to spend as much time,going over the customers story,explanation and situation,as you do investigating hidden loads and testing.

As for what it may be...i'm sure we could draw a list of at least 50 historic reasons,all found after a similar customer call.

 

[marconi]

A few questions and thoughts:

1. What earthing system?
2. Are the pelmet fittings earthed or double insulated?
3. What final circuits are protected by (a) RCD and (b) no RCD?
4. Any water leaks recently?
5. IR test results?
6. PAT test results of appliances with a heater element?
7. Has the fault started since we have had rain?
8. Is the switch single of double pole?
9. Check polarity of pelmet circuit and kitchen light circuit.
10. EP bonding correct?
11. Isolate each pelmet until non are connected. Check IR of pelmet fittings.
12. Swap the switch.

 

[Bob Geldoff1234]

Try taking the all the neutrals out of the lighting circuits on the non rcd side and switch on the lighting breakers temporarily.Try the pelmet lights.If they are still on then they have borrowed the neutral from the RCD side.Also after putting everything back together,see which breaker isolates the pelmet lights just to make sure it's not on the rcd side.

 

[telectrix]

Try taking the all the neutrals out of the lighting circuits on the non rcd side and switch on the lighting breakers temporarily.Try the pelmet lights.If they are still on then they have borrowed the neutral from the RCD side.Also after putting everything back together,see which breaker isolates the pelmet lights just to make sure it's not on the rcd side.

i'd be very careful here. with the neutrals dissed from supply N,they will become energised to 240V with loose ends floating about.a dangerous practice, IMO.

 

[Bob Geldoff1234]

i'd be very careful here. with the neutrals dissed from supply N,they will become energised to 240V with loose ends floating about.a dangerous practice, IMO.

I am talking about doing this for mere seconds to confirm things.Obviously it is dangerous to do.

 

[Rikmac]

A few questions and thoughts:

1. What earthing system?
2. Are the pelmet fittings earthed or double insulated?
3. What final circuits are protected by (a) RCD and (b) no RCD?
4. Any water leaks recently?
5. IR test results?
6. PAT test results of appliances with a heater element?
7. Has the fault started since we have had rain?
8. Is the switch single of double pole?
9. Check polarity of pelmet circuit and kitchen light circuit.
10. EP bonding correct?
11. Isolate each pelmet until non are connected. Check IR of pelmet fittings.
12. Swap the switch.

Thanks for reply
1 TNC-S
2 earthed class 1
3 RCD, SKTs,Boiler,Cooker,Water heater
None RCD, Lights
4 No leaks or any works been done
5 >200
6 Haven t done that
7 didn't ask that question
8 single
9 polarity correct
10 yes
11 done that its correct
12 your the second person to say that so will do although im not convinced haha

 

[Rikmac]

A few questions and thoughts:

1. What earthing system?
2. Are the pelmet fittings earthed or double insulated?
3. What final circuits are protected by (a) RCD and (b) no RCD?
4. Any water leaks recently?
5. IR test results?
6. PAT test results of appliances with a heater element?
7. Has the fault started since we have had rain?
8. Is the switch single of double pole?
9. Check polarity of pelmet circuit and kitchen light circuit.
10. EP bonding correct?
11. Isolate each pelmet until non are connected. Check IR of pelmet fittings.
12. Swap the switch.

Thanks for reply
1 TNC-S
2 earthed class 1
3 RCD, SKTs,Boiler,Cooker,Water heater
None RCD, Lights
4 No leaks or any works been done
5 >200
6 Haven t done that
7 didn't ask that question
8 single
9 polarity correct
10 yes
11 done that its correct
12 your the second person to say that so will do although im not convinced haha

Try taking the all the neutrals out of the lighting circuits on the non rcd side and switch on the lighting breakers temporarily.Try the pelmet lights.If they are still on then they have borrowed the neutral from the RCD side.Also after putting everything back together,see which breaker isolates the pelmet lights just to make sure it's not on the rcd side.

 

[Rikmac]

I am talking about doing this for mere seconds to confirm things.Obviously it is dangerous to do.

Will try this
I work live more than would care to admit so its not a problem