Made me jump!

Mjward · Jun 9, 2021

Moved into a new house and before I make a start on the serious renovation, thought I'd mount a TV so I have some evening entertainment.

Easy, the previous owners already had one up, just need to move along slightly for new pilot holes for the new bracket. Or so I thought.

Drilled first pilot hole, no issue.
Drilled second pilot hole and lights in room went out. (I didn't connect the two immediately as the microwave was on and this earlier triggered the RCBO).
Drilled third pilot hole and poof, bit of a spark, RCBO triggered again and told me something was not right.

The things that are alarming me are:

1) I've drilled a couple of inches horizontally from where previous mount was installed. Closer to a power socket but nowhere near above. Further away from a light switch and in no logical route of a cable run

2) the room lights are switching off when there was a power overload earlier on the sockets. Don't know why these would be on same RCBO.

This house is completely new to me less than a week ago so don't have a full understanding of the electrics but there s growing number of warning signs that something isn't right

Mjward · Jun 10, 2021

nicebutdim said:
OP states RCBO protection. Perhaps an image of CU might help.

Curious to know which hole caused the initial trip and which hole caused sparking.

Looks like only one RCBO in fact and not part of circuit in question. I think most of you will enjoy a good laugh not only at the state of the CU but the labelling! It was the top right hole that caused initial trip, then the middle hole that caused the spark.

Mjward · Jun 10, 2021

Dartlec said:
Looks like I'm relatively local @Mjward so could arrange to pop in and have a look at some point - having a bit of a nightmare week, but might be able to arrange something.

What tripped - RCD that covers multiple circuits, or an RCBO just covering one circuit? You really need to locate the damaged cable in the wall and repair it before using the circuit in question again.

Are they stud walls? If so horizontal wiring is normally fairly rare if there's no socket to the left (though might be one on the reverse of that wall?)

Hello, very kind offer but unfortunately that is my old address, I'm up in West Yorkshire now if anyone is local to that area?

Plan is to chisel out the area today and assess the cable situation. Have now turned off the RCDs that cover the area in question (both lighting and power).

WIth regards to wall structure itself, this wall forms part of a fairly modern extension to a property from 1900, i.e. its attached to the old property's external wall. From knocking on the wall, there are definitely hollow voids but bizarrely where the original bracket was positioned sounds incredibly hollow vs where I was attempting to relocate to was solid as you like.

brianmoooore · Jun 10, 2021

D and C curve MCBs? 10A lighting circuits?

telectrix · Jun 10, 2021

it will be dot and dab. the hard parts are where the dabbers have splodged their fixative.

DPG · Jun 10, 2021

If something tripped when the 1st hole was drilled, but then you still got a spark when the 2nd hole was drilled then maybe you have drilled through two separate circuits? Or did you reset the tripped device after the 1st incident?

Loving the protection devices in the CU by the way. And the secret light!

SJD · Jun 10, 2021

Looks like a board someone got surplus or second hand, repurposed for domestic use. Except likely some of these circuits won't comply, e.g. sockets on a D32 MCB. Quite apart from the dangerous large holes with what looks like exposed live copper.

Mjward · Jun 10, 2021

Dot&dab would make sense and only makes sense they mounted their bracket in the void as they were aware of the cable runs.

I believe I reset the tripped device after the first trigger (as I incorrectly assumed the new microwave had set it off again). On the plus side, hopefully means I've only drilled into one circuit.

The CU has definitely rung enough alarm bells for me to now seriously consider a full house rewire. Its a very similar system to the plumbing where they have added to it over the years, not removing anything redundant i.e every room is a whole mess of things that do and don't work. The joys of home ownership.

telectrix · Jun 10, 2021

i can highly recommend an ex-member used to be on here. he's NICEIC approved contractor, not a short course DI. (althoughsome of them are competent). he lives in Leeds.

nicebutdim · Jun 10, 2021

Mjward said:
Looks like only one RCBO in fact and not part of circuit in question. I think most of you will enjoy a good laugh not only at the state of the CU but the labelling! It was the top right hole that caused initial trip, then the middle hole that caused the spark.

View attachment 86548

Can you indicate which specific device or devices tripped on each occasion?

Mjward · Jun 10, 2021

telectrix said:
i can highly recommend an ex-member used to be on here. he's NICEIC approved contractor, not a short course DI. (althoughsome of them are competent). he lives in Leeds.

That would be much appreciated

Mjward · Jun 10, 2021

nicebutdim said:
Can you indicate which specific device or devices tripped on each occasion?

I would just be guessing I think. I know two went, I believe one of the main RCCB and then a circuit RCD

Mjward · Jun 14, 2021

Started chasing out and I couldn't have targeted the wires any better

Mjward · Jun 14, 2021

Looks like I hit a main route. Managed to piece two wires but interestingly someone else had pierced another two but decided to leave them. Also found out why it sounded so hollow, probably one of the most spaced out and deep dot and dabs going

littlespark · Jun 14, 2021

Is there anything to say that’s a safe zone? In line vertically with socket or anything? Even on other side of the wall?

Mjward · Jun 14, 2021

littlespark said:
Is there anything to say that’s a safe zone? In line vertically with socket or anything? Even on other side of the wall?

Walls are over 2 foot thick (Henry Hoover for reference!) as this is the old house exterior to extension wall and no sockets on other side. Adding additional photo for wall context. What I struggle to understand is given this is all "new" cabling ie fixed to exterior of original house when extension was put in, why would so many cables be routed here when the consumer unit is on the other side of the house and from what I can tell these cables don't even supply any of the sockets immediately to the right (but I will be doing more chiselling to find out)