Redundant Cooker cable in wall.

Ganga

gutovicky said:

OK, Thanks everybody.
Just to clarify, in case there's anything different anyone wants to add....

I live in a detached bungalow.
The electrics in the property are quite 'simple' - just one Consumer Unit (an old-fashioned one with fuses that I can pull out).

But I do have 2x power switches: an 'original' one, to the side of the rack of fuses, and a more recently-fitted/modern RCCB (with a test button) wired into the system.

When I hit the cable in the wall with a drill, there was a bang and a flash, and all the house electrics cut out - the modern RCCB had tripped (I can't remember whether the older, original CU main switch tripped or not). 
When the electrics were switched on again at the CU, the cooker was not working.

I took the 30A fuse for the cooker out of the fuse box (CU).  Thinking I was safe, I did some more drilling (well away from where I believed the cooker cable to be !).
Unfortunately, I must have hit the cooker cable again, because the house electrics once again cut out suddenly (I discovered that the wiring travels DIAGONALLY across the wall !). 
I have since learnt about the risk of turning a neutral wire into a live wire by bridging - which is what must have happened when the drill made contact - creating the differential that tripped the RCCB.

All this sounds reckless I know.   I have learnt by the experience.
As a way of salvaging the situation (& allowing me to complete the dismantling of this section of wall), I was intending to cut the cable in the loft and fit a terminal box (separating the component wires) - exactly as FreeBear describes (see 6th Dec. post).

Has anyone got any further comments or suggestions now that I've given more information?
Cheers, Vicky


 

 

Take out good life insurance 

Section62

grumbler said:

What "dead stick"? It was long time ago

Now it's

diystarter7 said:

Hi OP

....I always dobut the cables and if drilling near a plug//switch etc i always test for metal/current.

and

...which still won't prove a cable is dead.

And testing for current will be the wrong test in the OP's circumstances.

OP - you need to be able to test the wire you are planning to cut to make sure it isn't energised.  The method of doing that has been described in the thread, but it requires equipment that most people don't have.

If you don't have the equipment and follow a safe method of working, there is a risk of you cutting into a wire which is energised.  Also bear in mind that a loft is a confined space, and that getting medical attention if you receive an electric shock while working in the loft won't be that straightforward.

Make sure you don't make it 'third time unlucky'.

Section62

grumbler said:

gutovicky said:

I have since learnt about the risk of turning a neutral wire into a live wire by bridging - which is what must have happened when the drill made contact - creating the differential that tripped the RCCB.

 

This makes no sense to me. RCCB is tripped by a small current leaking to earth.

Bridging live and neutral creates short circuit and high current that trips either a MCB or a fuse.

This is where (I assume) @Risteard would point out that in this context the neutral wire is a 'live' wire and that shorting it to the CPC by drilling into the cable would create the circumstances where a current differential will be sensed by the RDC and trip it (hopefully).

Which is why electricians use the word 'live' differently to the way a layperson would.

grumbler

Section62 said:

grumbler said:

What "dead stick"? It was long time ago

Now it's

diystarter7 said:

Hi OP

....I always dobut the cables and if drilling near a plug//switch etc i always test for metal/current.

and

...which still won't prove a cable is dead.

And testing for current will be the wrong test in the OP's circumstances.

What current? It was about checking the wall when drilling it.  And normally a cable can only be detected if it's live. Do you suggest switching all electricity in a house off every time you drill a hole?

diystarter7

grumbler said:

SergeantBaker said:

diystarter7 said:

Hi OP

From what you have said, personally, I'd get someone in.

What I do is as per previous posts check all is off with a tester.

Re cables, yep, we too had cables like yours and this is where a metal/electrical tester is worth its money in gold.

In any new house, I always dobut the cables and if drilling near a plug//switch etc i always test for metal/current.

I hope it works out for you and with electrics you need to get it 100% spot on.

Good luck with whatever you decide to do and I'm sure someone else may say differently to me.

Thanks

OP, please don’t listen to this person. He’s recommending the wrong sort of tester to prove dead. 

If you go onto YouTube watch artisan electrics latest video where Jordan a qualified electrician was caught out using much more sophisticated testing equipment than the recommended dead stick. 

What "dead stick"? It was long time ago

Now it's

diystarter7 said:

Hi OP

....I always dobut the cables and if drilling near a plug//switch etc i always test for metal/current.

and

Hi

Many, many thanks, appreciate that.

We found it to be really food for us and as per the previous post we have a screwdriver tester and a plug tester.

IMHO, if one is a Diyer and or helping their children with their property, the above gadget is priceless.

Anything we are not confident with, we seek a professional as not of my family are builders/plumbers/corgi/electricians/roofers/etc etc but like most people, we like to save money and at times do a much better job than the person we may call in

It is a sturdy product and a name that me and the family trust.

Thanks again, appreciated.

Section62

grumbler said:

Section62 said:

grumbler said:

What "dead stick"? It was long time ago

Now it's

diystarter7 said:

Hi OP

....I always dobut the cables and if drilling near a plug//switch etc i always test for metal/current.

and

...which still won't prove a cable is dead.

And testing for current will be the wrong test in the OP's circumstances.

What current? It was about checking the wall when drilling it.  And normally a cable can only be detected if it's live. Do you suggest switching all electricity in a house off every time you drill a hole?

The post you quoted said -

"....I always dobut the cables and if drilling near a plug//switch etc i always test for metal/current."

Section62

diystarter7 said:

It is a sturdy product and a name that me and the family trust.

The reviews on the Truvo are mixed and it has no manual sensitivity adjustment.  Furthermore, it probably needs to be returned to Bosch from time to time for recalibration.

Most importantly, it cannot test for dead, and does not measure or test for current.

fenwick458

that bosch truvo thing is a glorified stud finder. you can't use a non contact voltage detector to prove dead, it has to be a tester with probes like this 

grumbler

fenwick458 said:

that bosch truvo thing is a glorified stud finder. you can't use a non contact voltage detector to prove dead, it has to be a tester with probes like this 

Now, can you explain, please, how to use this tester with probes for detecting wires when drilling a wall (that's what it was suggested to use for).

chris_n

Too much ambiguity on here, which becomes very dangerous when misunderstood.