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 23, 2021

Great shout. Turned around and saw what from afar I initially thought were TV points... But alas were prewiring for speakers!

Many thanks all

littlespark · Jun 23, 2021

Don’t like that they used the same coloured core flex as mains voltage cables.
Test it for voltage before connecting your big expensive speakers!

Mjward · Jun 23, 2021

littlespark said:
Don’t like that they used the same coloured core flex as mains voltage cables.
Test it for voltage before connecting your big expensive speakers!

Totally agree which is what confused me the fact it was coloured live and neutral wires. Tested it already and no voltage, helpfully even labelled with a yellow tape on one so I know L and R speaker locations ...small victories

SJD · Jun 23, 2021

Deleted (after reading other posts) ( I was going to suggest L & R speakers).

GBDamo · Jun 23, 2021

Sound quality will be terrible, that's not O² free, gold plated, rolled on the thighs of faeries cable that he Hi-Fi shop told me I needed.

Mjward · Jun 23, 2021

GBDamo said:
Sound quality will be terrible, that's not O² free, gold plated, rolled on the thighs of faeries cable that he Hi-Fi shop told me I needed.

???? A bit like those extensions leads "designed for audio equipment"...only £200 pls!

MJPD29 · Jun 23, 2021

Could be being used as speaker cable, any surround sound wired?

telectrix · Jun 23, 2021

littlespark said:
Don’t like that they used the same coloured core flex as mains voltage cables.
Test it for voltage before connecting your big expensive speakers!

they do exactly the same with fire alarms. brown/blue FP200 for 24V D.C.

OnlQQker · Jul 1, 2021

Mjward said:
Right...so I've got a cable route which has some coax, ethernet and these two random white cables with brown and blue wires terminated in a chocbox.

For life of me can't figure out why they were routed there or what they do. Anyone have a guess where they may be routed near a TV location? Hopefully can use that information to figure out where they end up as haven't found the other side yet!

View attachment 87022 View attachment 87023

They look to me like 2 extension lead cables (with the earth cut back possibly?) which once went into a couple of fused plugs. But I'm only guessing here so finding the other end end first might help.
Anything in the other rooms or garage that seem like a ?̶?̶?̶?̶?̶ add on?

telectrix · Jul 3, 2021

OnlQQker said:
They look to me like 2 extension lead cables (with the earth cut back possibly?) which once went into a couple of fused plugs. But I'm only guessing here so finding the other end end first might help.
Anything in the other rooms or garage that seem like a ?̶?̶?̶?̶?̶ add on?

think he's established (at my suggestion) that they are wired to 2 remote speaker locations.

Mjward · Jul 11, 2021

Thought best adding to this thread rather than starting a new one for every time I discover something. Starting basic electrics on one room (non-notifiable), broke into ring main to add 3 extra double sockets and now trying to understand the current lighting wiring as plan to migrate from a one-gang switch single pendant fitting to a two-gang switch for downlights and LED strip.

We recently bought the house and were told it had recently undergone a full rewire. Vendors were unable to produce electrical certificates and LA didn't have on file but we proceeded with purchase thinking it's not the end of the world if it needs full rewire but would rather avoid.

First real test of the "recent" rewire was when I looked behind the switch in one room and tracked the wires to the current light fitting. For a start given wiring colours changed in 2006 I'm not wholly convinced "recent" as appropriate but after spending many months studying current lighting regulations/wiring diagrams and so forth I am a little perplexed as to what is going on here.

Images below for reference plus my quick knock up in paint (apologies for bodged up colours, red = live, blue = neutral, green = earth) as to what is going where. My questions:

1) Is it a previously acceptable setup i.e. no reason to change it?
2) With the feed going to the switch and not a ceiling rose, if I wanted to add a second set of lights (moving to 2-gang switch) am I right in assuming that I can just simply connect a T&E from new second light to switch?

Mike Johnson · Jul 11, 2021

Carefully have a look at the live (Brown) hanging down from the ceiling it looks as though it has been nicked when the outer sheath was removed with a knife.

Mjward · Jul 12, 2021

Mike Johnson said:
Carefully have a look at the live (Brown) hanging down from the ceiling it looks as though it has been nicked when the outer sheath was removed with a knife.

You're right. From what I can tell it's a bit of a gift and a curse setup. Although old school single&earth and single core neutral setup, the plus side is with feed at the switch it's going to be much easier to run additional light

Mjward · Jul 26, 2021

Finding a few more delights in this place. Maybe it's my OCD but is the norm for electricians when doing a rewire to leave the existing cables in place and just left cut in between floorboards?

Brings me onto an actual question: any idea what these could be for in the 2 pictures? (My guess is that the white cable with multi coloured wires is perhaps for the security system PIRs all over the place but why randomly connect them between floorboards of a bedroom and living room? The other external metal pin I have no idea)

loz2754 · Jul 26, 2021

It's good practice to remove redundant cables and switchgear, sadly not everyone follows good practice.

The jointed alarm cables are indeed a right mess and should be enclosed in a box of some kind. As to the reason they've been joined here - either some berk chopped through them accidentally, or the alarm panel has been moved to a different location.

The metal pin is an early earth rod, usually installed when the earthing arrangement is TT.
Again, poorly installed, with no proper means of connecting the cable, and no protection from the elements. There should be an inspection pit sunk in the ground.

Mjward · Jul 26, 2021

loz2754 said:
It's good practice to remove redundant cables and switchgear, sadly not everyone follows good practice.

The jointed alarm cables are indeed a right mess and should be enclosed in a box of some kind. As to the reason they've been joined here - either some berk chopped through them accidentally, or the alarm panel has been moved to a different location.

The metal pin is an early earth rod, usually installed when the earthing arrangement is TT.
Again, poorly installed, with no proper means of connecting the cable, and no protection from the elements. There should be an inspection pit sunk in the ground.

Thank you! Will enclose them in a MF box and affix to the joist. As for the earth rod, other than tracing back to CU is there a way I could test if it actually forms part of the current circuit as I'm uncovering a lot of redundant wiring.

loz2754 · Jul 26, 2021

Mjward said:
Thank you! Will enclose them in a MF box and affix to the joist. As for the earth rod, other than tracing back to CU is there a way I could test if it actually forms part of the current circuit as I'm uncovering a lot of redundant wiring.

From the look of the earth rod, and the wire connected to it, it looks likely to be not in use. A picture of the main earthing terminal (either in or near to the consumer unit) may reveal whether the rod is in use or not.

Mjward · Jul 26, 2021

loz2754 said:
From the look of the earth rod, and the wire connected to it, it looks likely to be not in use. A picture of the main earthing terminal (either in or near to the consumer unit) may reveal whether the rod is in use or not.

Suspect you'll need a different angle but here is one I have on file if of use

brianmoooore · Jul 26, 2021

That could be an old telephone earth.

Mjward · Jul 26, 2021

brianmoooore said:
That could be an old telephone earth.

Funnily enough...where it enters the property is where the BT line comes in. If that is the case, is it redundant or still required?

brianmoooore · Jul 26, 2021

No. The old style lightning arresters needed an earth. Modern ones don't.
What does the BT line come into?

Mjward · Jul 26, 2021

brianmoooore said:
No. The old style lightning arresters needed an earth. Modern ones don't.
What does the BT line come into?

A few supplementary pictures showing cables entering the property (terminating into BT box), external view of cables (3 going into property, including the 1x earth, 1x cable from telephone point, 1x unknown) and a view of the telephone point which has an overhead wire taking it to a BT pole on the street.

brianmoooore · Jul 26, 2021

The wring that originally went with those insulators on the wall bracket would have needed an earth wire exactly like the one in your pic.
I removed the last traces of ours when I re roofed and upgraded the porch last summer.
The earth wire would have gone into a rectangular Bakelite box mounted where your BT master is now.

polaroid · Jul 26, 2021

Mjward said:
A few supplementary pictures showing cables entering the property (terminating into BT box), external view of cables (3 going into property, including the 1x earth, 1x cable from telephone point, 1x unknown) and a view of the telephone point which has an overhead wire taking it to a BT pole on the street.