Fault Find # 2

[Paul.M]

Easy one for you.....

Domestic house, 17th ed dual split cu, RCD1 will not reset after a plaster "tripped" the mcb and rcd earlier in the day. Plasterer has been working in the kitchen only and re-boarded the ceiling and skimmed it only (no walls). Kitchen sockets work as they are on RCD2. Kitchen lights are on RCD1 and its a one way lighting circuit in the kitchen for a simple 3 plate (loop in, loop out) baton.

Please give a step by step course of action. I'll give you the first one.

1. The kitchen sockets work so put the kettle on, milk 2 sugars please

 

[High Tower]

Nice !!, i like it mate.

2, Tell the plasterer he is a Div, and explain that this is why he shouldnt be trusted with anything sharper than a bucket!

Over to you guys!

 

[Paul.M]

HT I'll reply to that once the answer has been given. Its a classic and thats why I took a photo of the fault to back up the elderly customer.

 

[Baker1988]

Hi ya i would say more then likely the plasterer has screwed the bored to the joists and have put a screw through the mcb and caused a short circuit what has tripped the rcd and mcb,
the first thing i would do is turn all the mcbs off on the rcd that trips then turn the rcd back on then one by one switch each mcb on until the rcd trips then that will show me which circuit the fault is on, then i would do insulation resistance test on the circuit that i found to be the problem and that would show that there would be a fault probily between l and n then i would go to about half way on the circuit and disconnect the wires and do another ir test on each leg and find which side of the circuit the fault is on then work my way back till i found the bit of cable that is the problem then go up stairs remove the floor boards and change that bit of cable.

but all this is basically speculation as it could be a number off faults but this is what i think it would be so not gone further than this.

 

[Paul.M]

"Hi ya i would say more then likely the plasterer has screwed the bored to the joists and have put a screw through the mcb..."


I' sure you meant to say "cable" so I'll let you off mate

You've got it, the plasterer missed the joist with his screw and put it through the 1.5mm T+E switch cable. You've over complicated this one my friend with all those tests you are going to do. All it needs is to know where the mechanical damage has been done (in this case its only the kitchen ceiling that is being worked on and it was the plasterer that made the rcd and mcb trip). When fault finding you ALWAYS HAVE TO ASK THE CUSTOMER WHAT HAS BEEN WORKED ON. The circuit worked yesterday, why not now? Oh the muck spreader has gotton carried away with his cordless driver lol.

What I did and what you should do is:-

Test at the ceiling rose for continuity in bertween all conductors. It does not matter which sequence but I start at the switch wire, L to N, L to CPC and N to CPC. This showed that I had a short circuit across all 3 conductors on the switch wire only.

How to resolve the fault:- Due to the tiled bathroom floor above I could not gain access from there. I put a nice big hole in the ceiling to get to the damaged cable (permission was given by the customer before doing this and I told her to get the plasterer back to repair my damage free of charge to her, its his fault lol). Now, if there was enough cable in the ceiling void I would have cut and repaired the cable using maintenance free wago's and a choc box but there was no slack on the cable so I ripped out the switch wire and replaced with a new from the switch to the rose, leaving a bit more work for the plasterer to do pmsl

I left the customer with a written statement from myself to the plasterer explaining what he did and he should pay for the call out charge to myself. (always have an A4 pad in your van and take photos).

 

[Marvo]

.....and I told her to get the plasterer back to repair my damage free of charge to her, ........replaced with a new from the switch to the rose, leaving a bit more work for the plasterer to do pmsl

Hope the hole you left was at least 2 feet square if not larger

 

[Paul.M]

Hope the hole you left was at least 2 feet square if not larger

Larger! It was fleshly skimmed so I could see the joints on the boards, took the full ceiling board down to get to the fault. I also had to chase to the switch, that was not pretty when I was done lol.

Strange how the plasterer did not call me to contest the extra work he had to do? Maybe something to do with the wording in the letter I left with the 80 year old customer lol. I hate people taking advantage of the old, boils my blood