RCBO Tripping Problem

[MarkP]

Hi people.

I've got a problem with a downstairs lighting circuit I've installed. It consists of a single pendant light in the lounge and three 50watt spots in the kitchen. I wired everything in yesterday and everything worked fine. But today I've trimmed some of the cables in the switch back boxes today to make them sit better and things have gone wrong! I ended up taking my lighting face plates off and just connecting on thing at a time starting with the kitchen spots. Now as so as I flick the switch the rcbo trips. I also seperately wired the lounge pendant in and everything was fine there, no tripping. I've check all my terminations and everything is tight a secure and everything is where it is suppose to be. I haven't touch or done anything to the wiring of the rcbo. Please help!

 

[martinxxxxxx]

I would fault find this as follows.

1. remove all bulbs and see if the rcbo sets
2. Isolate/ test for isolation
3. if not open pendant and remove incoming and out going live feeds from terminal block, see if it sets then.
4. do the same for the jnc box for the kitchen spots.
5. Once you have disconeected and identified the light circuit that is causing problems . Do some IR checks around to find where the fault lies

Good Luck Martin

 

[Mr Mark Sparks]

could it be a faceplate screw pinching something
maybe hard to spot

 

[martinxxxxxx]

Obviously you have disturbed something to create the fault condition. I would guess a nicked sheathing on a switchwire from what you have said. You might, as there are so few of them, just whip them all off and have a look it might be obvious.

Martin

 

[MarkP]

You might, as there are so few of them, just whip them all off and have a look it might be obvious.

Yeah I did that but couldn't see anything untoward. Going to check the spots tomorrow and see how we go. This is the first time I've wired the majority of a house on RCBO's so didn't expect it to be smooth!

 

[martinxxxxxx]

I hate this stuff I have recently brought a LOCAT 220 from RS 212-152 so I can hopefully quickly find this sort of problem, I always feel like a prat when the customer is watching me try to get rid of a fault that it is clear I have introduced.

You could have sliced into the insulation when you remade the connections - very hard to spot. IR testing will reveal it though. But you will have to isolate the switch drops as they will all show low ohms. See my earlier method. I would tell the customer I have to re tighten check the connections. If you go about this in a logical manner 1 hr fault finding tops. Flit from here to there and you could be chasing shadows all day.

Half split and keep going till you find it - good luck

Martin

 

[Guest123]

Hi.

Could you now have a SW + N mixed up in the switches perhaps,

Just trying to throw some ideas out there.

 

[martinxxxxxx]

Hi.

Could you now have a SW + N mixed up in the switches perhaps,

Just trying to throw some ideas out there.

In OP he said it was all working yesterday until he did some work tidying the cable behind the faceplates - so maybe unlikely

Martin

 

[Guest123]

In OP he said it was all working yesterday until he did some work tidying the cable behind the faceplates

My point exactly.

 

[martinxxxxxx]

I am going to show my stupidity here why is there neutral in the face plates.. I just know you going to say my point exactly to this too.

 

[Guest123]

Well maybe the feed is at the switches as there are recessed spots involved....makes it easier to wire the supply into the switch and SL + N out to the spots.

This is all hypothetical as you nor I know exactly whats going on there.

 

[Eggster71]

I am going to show my stupidity here why is there neutral in the face plates.. I just know you going to say my point exactly to this too.

Another handy reason for a "2 plate" switching system is when wall lights are to be installed, you do NOT wanna be terminating loop in, loop out, switch line and switched loop out inside some of today's impossibly small decorative fittings, I recently had to install some in a bathroom with a 25mm diameter base!

 

[MarkP]

I would tell the customer I have to re tighten check the connections.

Thankfully it's my sisters house and it is vacant at present.

Could you now have a SW + N mixed up in the switches perhaps.

Nar, definately not a problem with the SW or N as I've terminated the neutrals together.


Didn't get chance to call after work today but will try tomorrow.

 

[yido]

done that pulling additonal cabling in singles through lighting circuit was tight old 3/8th tube was getting high earth loop impedance and rcbo tripping although didnot trip on 60898 yes lol i had taped and lubed on pull through nicked other cable in tubes why do these things happen on friday afternoons at about 3.45pm started again and its always always the last one you look at whatever sequence you do sods law more like sparks law