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sparkyork

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hi all, first of all ive just got in from work, had they day from hell and im shattered! did a consumer unit change, test and a couple of minors works all on same job, as well as having to repair a pipe that was not supposed to be wear i was clipping (fecking plumbers!) they never heard of zones!

anyway all was well new board running nicely for a few hours, i did get a low ish reading on N-E on upstairs lighting of about 8 Mohms, but didnt think it would cause rcd to be a prob as ive always had much lower readings on rcd faults due to insulation resistance.

rcd only trips when the landing ceiling rose is switched ( i think ), there was an old energy saving lamp in it that i noticed was just flickering which seemed odd, like it was backfeeding off something?? any way took the bulb out reset rcd and tried the switch again, "trip" off it goes, disconnect lampholder just leaving rose and i can operate switches and its ok (so presuming strappers have gotta be ok, as i tested these when Ins Testing anyway)

didnt have a spare lampholder in van so couldnt try a new one, im off back there tomorrow afternoon, anyone got any ideas for a tired fellow spark!?

ps both rcd's are going, which also dont seem to be a compliance with the 17th either!!! sure it sounds like some sort of strappers problem occuring when a load is been switched but im confised.com
 
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sounds like borrowed neutral problem upstairs lights have upstairs neutral. And i'll guess the feed is taken from the 2g 2way on the downstairs circuit.

Mark
 
S

sparkyork

  • Thread Starter Thread Starter
  • #3
cheers mark i was thinking on the same lines me self spesh as its all ok at the minute but as soon as any load is applied to that rose it all goes. why did they have to wire it like this!!

but why would it do it with a lampholder wired in and not trip when it was out?? the lampholder wiring is above 500M ohms
 
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Just to give you something to do in the morning and keep you outta the pub

Mark

cheers mark i was thinking on the same lines me self spesh as its all ok at the minute but as soon as any load is applied to that rose it all goes. why did they have to wire it like this!!

but why would it do it with a lampholder wired in and not trip when it was out?? the lampholder wiring is above 500M ohms
Sparky its tripping out because 1x lighting circuit is connected to both RCDs

You need to take a neutral to the landing light from the downstairs circuit and take out the neutral that is there now

,Mark
 
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sparkyork

  • Thread Starter Thread Starter
  • #5
yeah now ive had chance to relax it all makes sense now!! im gonna have to reconnect the upstairs neautrals tho cos there looping off to something esle as well.
 
E

EasyFox

This is going to be a common problem.
Quickest way to check, bang all the lights onto one rcd.
 
R

rumrunner

cheers mark i was thinking on the same lines me self spesh as its all ok at the minute but as soon as any load is applied to that rose it all goes. why did they have to wire it like this!!

but why would it do it with a lampholder wired in and not trip when it was out?? the lampholder wiring is above 500M ohms
I understand the borrowed neutral thing ,but cant get my head around why it trips with the lamp removed,:confused:
 
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EasyFox

Rum it doesnt trip with the lamp removed (unless I've had one beer to many) no load.
 
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rumrunner

Rum it doesnt trip with the lamp removed (unless I've had one beer to many) no load.
what hes saying is with the lamp holder connected it trips and disconnected it doesnt .i presume that he removed the lamp first ,still cant get my head around it maybee i need another beer :)

cheers mark i was thinking on the same lines me self spesh as its all ok at the minute but as soon as any load is applied to that rose it all goes. why did they have to wire it like this!!

but why would it do it with a lampholder wired in and not trip when it was out?? the lampholder wiring is above 500M ohms
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sparkyork

  • Thread Starter Thread Starter
  • #10
ill confirm this wierd occurance tomorrow and post here!!

with an energy saving bulb fitted it was flickering slightyl and trippiing both rcds when switch was switched. i took bulb out and its still did it!! disconnected lampholder and everythings ok. i really dont get it either but thats how ive been able to leave the house tongiht so they can have some lights on!!

i will check again tommorrow, i even wondered of maybe the screws holding the rose up might be nicking the neutral above or something, but like easy and everyone else says as well as logic, it should only do it under load?????
 
P

PAUL M

i have come across the same thing a couple of months ago when first started using the 17th boards,i did a thread called beware the borrowed neutral,its quite a common problem in older properties.as easy said try putting all the lights on one rcd ,if it dont trip then you just got to persuade your customer to let you run a new neutral.have fun.
 
M

montybaber

The RCD will trip when it detects an imbalance between the phase and neutral on that circuit, the imbalance occurs when the switch live is energised on the landing light circuit 1 when the neutral belongs to circuit 2 it wont trip without lampholder due to you effectively taking the borrowed neutral out of circuit.

Thats how I see it anyhow...prob wrong:)
 
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R

rumrunner

The RCD will trip when it detects an imbalance between the phase and neutral on that circuit, the imbalance occurs when the switch live is energised on the landing light circuit 1 when the neutral belongs to circuit 2 it wont trip without lampholder due to you effectively taking the borrowed neutral out of circuit.

Thats how I see it anyhow...prob wrong:)
you are correct in what you say above,but....
Its tripping out with the lamp removed,and it doesnt trip with the pendant removed ,dangler insulation resistance is above 1/2 a meg ,whats the difference between taking out the lamp and removing the pendant?
very strange:confused:
 
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sparkyork

  • Thread Starter Thread Starter
  • #14
right ive got me morning job done and im off to go put another neutral in at this job, willl confirm this wierd thing that its doing, i also dont get what the differemce is with pendant removed not tripping rcd, theres no load going across it?

the customer was aware that often certain problems come up when changing boards and it should be cool. not gonna be easy getting neutral up tho, board is under staircase!!

defo a shoddy way of wiring things, the loop in loop out at the rose is live from upstairs lighting and sw/live is live from downstairs lighting, proper poo poo!! shock city!
 
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montybaber

you are correct in what you say above,but....
Its tripping out with the lamp removed,and it doesnt trip with the pendant removed ,dangler insulation resistance is above 1/2 a meg ,whats the difference between taking out the lamp and removing the pendant?
very strange:confused:
Sorry must've read it wrong... your right thats wierd :confused:
 
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sparkyork

  • Thread Starter Thread Starter
  • #16
yeah i tried it again before connecting the new neutral from the board and it didnt effect it with the lampholder and been connected, i didnt use the old one tho it was a new one.

unless i was tripping out me self! im sure it did what ive wrote last night! with the bulb out it was still taking the rcd out, dont get it at all but hey ho its all ok now anyway! guess it was on of those un explained electrically mysteries!!
 
R

rumrunner

yeah bit strange ,all i can think of is the insulation in the flex or lampholder its self was breaking down ,and when you did ie test somehow it was clear ,had it happen with a motor once ,clear when cold ,dead short when running a few minuits,made me look a right [email protected] ,because i insisted nothing was wrong with the motor ,never mind hey
it all comes out right in the end
well done anyway
 
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tony.towa

Hi Rich

Glad the problem is solved. The other members seem to have covered every eventuality. Assuming that the cu is in a cupboard somewhere all I was going to say was that if you put all the lighting on one circuit you can stay in the cupboard and listen out for aircraft. If you hear any you know the landing light is on!!!!!!:D:D:D:D

Sorry just having a mad moment
 
J

jord35davies

I think I've got the answer to your problem. I had the same problem myself a couple of weeks ago. I did a consumer unit change and everything was working great until the landing light was switched on and off went the RCD. I had a faulty two gang switch to start with where as the brass screw wasn't really making a great connection with live(line) conductor. Secondly I had to remove the strappers that were there and run a new 3 core as a strapper. I then had to take a new supply off one of the bedroom lights to the landing light after that everything was fine. I spoke to an old spark friend of mine and He said it might have something to do with a junction box system and the junction box, chances are you would never find. Also be careful on the insulation resistance of the strapper. These new dual rcd consumer units pick up everything.
 
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sparkyork

  • Thread Starter Thread Starter
  • #20
gotta say probably as well as whats been said in paul m's thread as well, that its a crap way of wiring stuff, fancy having 2 seperate lives in a ceiling rose, i mean fair enough they didnt have rcd's to worry about but what about the poor spark who's changing the fitting with the landing light switch off downstairs, he tests with his prooving unit and everything is dead, then someone turns switch on downstairs, followed by lots of swear words!

i couldnt find an easy way of getting down to the fuseboard under the stairs so had to put a length of yt1 in the kitchen to bring the neatral down and into the cupboard, dont look great but if they decorate they can always chop it in!!

i could of got to a feed under the landing floor boards but was more inclined to go straight to the board itself, what other solutions are there to this?? my understanding of the 17th and consumers is that lighting could do to be on seperate rcd's etc so if the customer didnt want remedial work doing to put it right then the board wouldnt comply with the regs?

also in some situations it may be easier to take a new twin n earth to the landing light switch and a 3 core down to the hall light switch, thus keeping things seperate.

ps Tony, i didny here any 737's approaching but i think that was cos i couldn hear out for the "clcik" "clciking" going on with the rcd's, was quite a cool break beat, if it was recorded and put on a loop, you could add some harmonics and there you have it a christmas numnber one!
 
J

jord35davies

Your 4th paragraph sounds good. Cause thats what i done a few weeks back, as i said before.all the best
 
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