Search the forum,

Discuss lighting circuit problems in the UK Electrical Forum area at ElectriciansForums.net

G

glasgospark

upgraded board to dual rcd
everything ok
that night lighting circuit breaker trips rcd stays on
i go back try putting breaker back on trips after a couple minutes , every light in house working when breaker on
tried disconnecting all outside lights etc, also still tripped with every light switch in off position ,
after numerous attempts trying different things the rcd then tripped along with the mcb , now rcd wont stay on when lighting mcb is on everything else in house is ok , i have tried a different mcb for lighting and still happens , it also stayed on for 4 hours yesterday untill ittripped that night ,

no timers on circuit or anything

any thoughts
 
so, do the same on continuity, get an idea of the resisiance. then start opening fittings and switches. could be a trapped cable or a screw into a cable.
 
Get the IR meter on the case check no issues, are all neutrals in the correct order?
I had a similar issue once turned out to be a damaged cable below a floor board IR was >5 meg but when someone stood on the floor board it caught the nail below lucky find in the end,
I would love to meet the plumber who caused it
 
so, do the same on continuity, get an idea of the resisiance. then start opening fittings and switches. could be a trapped cable or a screw into a cable.
You suggest r1r2 every point , not done that yet , firstly it was McB only and would trip after minutes now rcd and it won't stay on atall
 
check the nail. if it's been put in with the nail head at the top, can't have been a plumber. probably a wood butcher.
 
Get the IR meter on the case check no issues, are all neutrals in the correct order?
I had a similar issue once turned out to be a damaged cable below a floor board IR was >5 meg but when someone stood on the floor board it caught the nail below lucky find in the end,
I would love to meet the plumber who caused it
Funny you should mention that , when it was just the McB tripping 2 times in a row at a squeaky floorboard when stood on it tripped straight away but after that nothing now it's rcd , which made me think its worked its way through the neutral cable now causing Imbalance on circuit and not a dead short ,
 
If the MCB trips after a few minutes it is either carrying about twice the rated current or something is heating up and then causing a fault. Clamp test the circuit of it can stay on and check the load.

Once this fault has occurred several times the expanding damage has now involved the cpc and caused the RCD to trip.

Split the circuit and IR test the sections until you can narrow down the location.
 
If the MCB trips after a few minutes it is either carrying about twice the rated current or something is heating up and then causing a fault. Clamp test the circuit of it can stay on and check the load.

Once this fault has occurred several times the expanding damage has now involved the cpc and caused the RCD to trip.

Split the circuit and IR test the sections until you can narrow down the location.
It's only pulling 2.8amp full load , I took earth out the circuit also and it stayed on for 4 hours then tripped , of course not a solution but I was testing the waters
 
you really need to split the circuit down and IR test in sections. only way.
 
If the MCB tripped and the RCD stayed on then initially you had a L-N fault so as advised check the whole circuit because I think you have agrivated the situation when you were switching the MCB on.

Also what was the point of this did you hope the fault would go away ?
 
You'd be just as quick to of disconnected all lights(there can't be many if this is domestic we are talking here) on the circuit and from the DB and has been said even if it means testing from point to point you will find the fault it may be at a termination or cable damaged it's not rocket science, you may even have to replace a length of cable God forbid, but find it you must you'll get there in the ,just break the circuit down.
 
You'd be just as quick to of disconnected all lights(there can't be many if this is domestic we are talking here) on the circuit and from the DB and has been said even if it means testing from point to point you will find the fault it may be at a termination or cable damaged it's not rocket science, you may even have to replace a length of cable God forbid, but find it you must you'll get there in the ,just break the circuit down.

Had the same thing a while back, builder had put a screw through a cable when fixing a batten up for a new ceiling. Disconnected the whole circuit at the first rose, then added and IR tested as I went until the faulty leg of cable showed up. Fairly straightforward to find after that.
 
Whats with this test each bit individually malarky? Split the circuit in half find the faulty half, split the faulty half and find the faulty half of that etc etc until you isolate the fault.
 
I was assuming there would only be half a dozen lights or so, I agree your method is the best way forward but I was trying to give him a sure fire way of eliminating light by light as he seems a bit stumped and your (the best method) just might confuse him if the lights are dotted all over the show lol
Whats with this test each bit individually malarky? Split the circuit in half find the faulty half, split the faulty half and find the faulty half of that etc etc until you isolate the fault.
 
Whats with this test each bit individually malarky? Split the circuit in half find the faulty half, split the faulty half and find the faulty half of that etc etc until you isolate the fault.

Half split technique is great, just so long as the circuit can be identified in that way.
I think the point that everyone is trying to make, is that "testing" of some kind is the way to go. Would still be interested to know what tests were carried out when the CU was installed...
 
if theres one thing i have learned about changing consumer units on houses after that job the other week , its to test absolutely everything before touching it , and then test everthing again after connections to new board before switching on , its not worth the grief to just batter on and do it and hope its ok ,thats how you end up on here in a panic , haha
 
racking my brains went back today testing at various points opening the feed cables at each switch one at a time , couldnt narrow it down to a certain cable or area , disconnected all switch wires(including n&e) still trips stays on for 3-4 hours today then trips ,

could be sitting with all switch wires out still trips :S
 
Well clearly the fault lays with the supply cable to the first point, disconnect the first point completely and IR the supply cables. I bet you will have a dead short there.
if nothing then IR after that point, you will find the issue.

something is telling me that your not a sparky as you have not even mentioned about your tester or test results, all its still tripping!

eitherway think about getting an electrician in before you kill yourself or a family member
 
Well clearly the fault lays with the supply cable to the first point, disconnect the first point completely and IR the supply cables. I bet you will have a dead short there.
if nothing then IR after that point, you will find the issue.

something is telling me that your not a sparky as you have not even mentioned about your tester or test results, all its still tripping!

eitherway think about getting an electrician in before you kill yourself or a family member
read back mate tester and results clearly mentioned , well n truly qualified 17th edition but thanks for the advice
 
Ok a IR of 0.2Mohms is not a fault in the first run unless a mouse had lunch early, its a long distance short or even a fault through a lamp.

whats the LE and NE readings at CU, 1st point, 2nd point, 3rd point, etc, etc, etc
 
Funny you should mention that , when it was just the McB tripping 2 times in a row at a squeaky floorboard when stood on it tripped straight away but after that nothing now it's rcd , which made me think its worked its way through the neutral cable now causing Imbalance on circuit and not a dead short ,

Did you lift the floorboard to investigate ?
 
Interesting thread
A lot of sound advice being given and plenty of fairly poor advice too.....
Its obviously not a dead short if its staying on for 4 hours.
Its Obviously not a L/N to earth fault because its the MCB tripping not the RCD (originally)
The first thought that sprang to my mind was a faulty transformer somewhere. I found this the other day when a client complained of an MCB tripping occasionally (it took me about 10 minutes)
Its hard to imagine its a damaged cable because I can't see how you could short L and N without shorting the cpc at the same time....unless of course that part of the cable has no cpc....
It'll be interesting to see the outcome
 
Sorry guys been M.i.a

been an on going job here customer only ever available now n then for around a hour ,
Found fault which was on the loop feed cable going between the 4th-5th switch , still haven't rewired it yet will be doing so next week , I'm thinking rodent or trapped along side heating pipe at boiler
 
trapped behind heating pipe. like it. blame wet-pants then. LOL.
 
or keep flicking the MCB on and on till it clears the short.
 
Sorry guys been M.i.a

been an on going job here customer only ever available now n then for around a hour ,
Found fault which was on the loop feed cable going between the 4th-5th switch , still haven't rewired it yet will be doing so next week , I'm thinking rodent or trapped along side heating pipe at boiler

Had a similar fault and situation a few months ago, could only ever spend an hour or so at the property, never ideal. Also, was never really a fault when I was there, was getting a 70meg IR and nothing lower, once it was in use for a few hours though it was then tripping, and found a multitude of small faults with nicked insulation, loose earths, loose connections, even an earth being used as a neutral link!

Was a squashed cable on top of a central heating pipe in the end, would have been solved a lot quicker and cheaper for them if they'd have told me the truth when I asked if they'd ever had a flood. Was being squashed more and more every time anyone walked along the upstairs passageway.
 

Reply to lighting circuit problems in the UK Electrical Forum area at ElectriciansForums.net

Similar Threads

An RCD keeps tripping. Please see attached photo of the board (2 photos attached). I’ll call the breakers: MCB (1) marked ‘Upstairs lighting’...
Replies
4
Views
1K
Having trouble figuring this one out. House was built 5 years ago. Eaton box and breakers. Over the past 3 weeks, the bedroom breaker keeps...
Replies
8
Views
703
I sorted the fault fairly quickly as it happens but only because I'd come across it once before and at the time a few people said it couldn't...
Replies
13
Views
416
Hi all, There's 2 single fan ovens in the house my mother recently moved into. Posh elecronic AEG units. It's been sat empty for a year, so the...
Replies
19
Views
2K
Hi all, Wondering if you could offer some advice please. I carried out a small outdoor lighting project today at a commercial property. 4 lights...
Replies
5
Views
983

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
Back
Top