Redundant Cooker cable in wall.

chris_n

grumbler said:

Section62 said:

grumbler said:

chris_n said:

How are you going to ensure the cable is dead before you cut it in the loft?

FreeBear said:

Turn the power off via the big red switch in the consumer unit.

- I have nothing to add...

I think the point might be that how do you know the big fat cable you've located in the loft is actually isolated by the big red switch in the consumer unit?

Do you know it is safe to cut, or is it just a case of guessing?

Do you mean that it can come from neighbours' house?

Normally there is one big switch in the CU that switches off all electricity in the house (not sure about solar panels and batteries). And how can you make sure if not by removing the cover from CU and testing the cable there? Again, how can you be sure that it's the same cable?

You isolate it and test it at the cut point, having first ascertained that power is there before isolation. You then pull the cable into the loft and cut / terminate. If you can't pull it back you use a tone generator to verify it is the same cable. Then you cut it and terminate it while wearing eye protection preferably, 1 core at a time using insulated tools suitable for the voltage you are working on.

Section62

grumbler said:

Section62 said:

grumbler said:

chris_n said:

How are you going to ensure the cable is dead before you cut it in the loft?

FreeBear said:

Turn the power off via the big red switch in the consumer unit.

- I have nothing to add...

I think the point might be that how do you know the big fat cable you've located in the loft is actually isolated by the big red switch in the consumer unit?

Do you know it is safe to cut, or is it just a case of guessing?

Do you mean that it can come from neighbours' house?

Normally there is one big switch in the CU that switches off all electricity in the house (not sure about solar panels and batteries).

Not particularly, although if you live in an 'attached' property there's always the potential for a cable in the loft to be coming from or going to a neighbouring property.

The key word there is "normally".  Some houses have two or more big switches, which might not be red.  Not necessarily with solar or battery storage either.  Having more than one CU is becoming more common as people's electrical demands increase.

grumbler said:

And how can you make sure if not by removing the cover from CU and testing the cable there? Again, how can you be sure that it's the same cable?

There are techniques I'd use, but I'm not going to describe them here on a public forum because I'd be concerned about the safety of anyone who took that as advice to attempt a DIY fix for their own problem.

A cable which has already been cut or damaged presents a significant safety risk for anyone inexperienced to try and repair or isolate.  Inspecting, testing or otherwise working on a live or potentially live system is inherently dangerous.

But a competent electrician would know how to do the right tests and what safe working method to adopt.

macman

Am I the only person wondering why you would run a  fairly chunky (6mm or greater) cooker cable all the way from a CU (presumably on the ground floor) to the loft, and then down to the kitchen again? 
Is this one of those upside-down houses with the kitchen upstairs?

diystarter7

macman said:

Am I the only person wondering why you would run a  fairly chunky (6mm or greater) cooker cable all the way from a CU (presumably on the ground floor) to the loft, and then down to the kitchen again? 
Is this one of those upside-down houses with the kitchen upstairs?

Hi

The important thing is to stay on topic for the OP to do it properly and safely and as per my previous post, I not only turn off the electrics but use a tester to see if any current is still there as I worry a lot.


Thanks

Section62

macman said:

Am I the only person wondering why you would run a  fairly chunky (6mm or greater) cooker cable all the way from a CU (presumably on the ground floor) to the loft, and then down to the kitchen again? 
Is this one of those upside-down houses with the kitchen upstairs?

OP has a bungalow.

macman

Section62 said:

macman said:

Am I the only person wondering why you would run a  fairly chunky (6mm or greater) cooker cable all the way from a CU (presumably on the ground floor) to the loft, and then down to the kitchen again? 
Is this one of those upside-down houses with the kitchen upstairs?

OP has a bungalow.

Well spotted! I was wondering which of you would be the first to notice that...

gutovicky

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


 

 

diystarter7

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



www.screwfix.com/p/bosch-truvo-digital-detector/8426T?kpid=8426T&ds_kid=92700048793290430&ds_rl=1244066&gclid=Cj0KCQiA1sucBhDgARIsAFoytUujZF4xSTEsBjb0HIV0KnLVUuw172vr_PgmeGVbwUYGw2__tKj3Y4MaArtyEALw_wcB&gclsrc=aw.ds 

grumbler

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

grumbler

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.