Replacing cable after drilling through existing cable!

[KPaul]

Hi all,

I had a lovely surprise yesterday afternoon when I was steaming some paint off a wall in our lounge. When I moved the steamer across a hole drilled by the previous owners it started to spark and cackle so I immediately knew what was wrong and turned the mains off.

Basically the previous owners left me a nice present to find which was that had drilled through an existing electricity cable running down to sockets. Even though I turned the mains off it still banged and sh!t the life out of me.

I chiselled away at the wall to reveal the exposed (and now burnt) cable, stripped it back and put a couple of choc blocks on to terminate it just so I could get the power back on. (I understand that it's effectively no longer a "ring" but I'm making sure I'm only drawing the minimal amount of power possible - this is okay isn't it?)

My dilemma is how to repair it with the minimal amount of fuss and mess. I have uploaded a couple of photos to show the current state of affairs. The options as I see it are as follows but please bear in mind that it was running in plastic conduit with the other cable from the ring mains and the conduit is located directly next to more conduit so it's pretty tight around there!

1) Take up the floorboards in the room above and replace the whole length of cable. The problem with this is that we have just recently done the room above and don't particularly want to go ripping up the carpeat, etc. The missus will kill me!

2) Get a sparky to crimp a new section of wire from the hole in the wall down to the socket. I do not mind paying for this at all as long as the crimped wire will fit back in the conduit? It seems pretty tight.

3) Chisel out the wall that covers this conduit from ceiling to socket and use one of these:

http://www.tlc-direct.co.uk/Products/ASJ803.html

behind the coving I will eventually put up and then run a new piece of cable down to the socket in new conduit.

4) Put an accessible junction box where the cable is shot. This will look so unsightly as it's right in the middle of the wall.

Where are peoples' thoughts? Has anybody come across this situation before (I'm sure they have!) and what did they do about it?

Many thanks,
Paul.

Untitled

• KPaul
• 1 Dec 2008
• 1

Untitled

• KPaul
• 1 Dec 2008
• 1

 

[Chri5]

If you can draw in a new bit of cable from the socket to the hole then your have 2 x ends that could be easily tterminated via crimping and sleeve.

Failing that your end up with a strap of cabel betwen the two points which again should be terminated via crimps.

ideally it would be best to replace the full length of cable, but thta is unlikely to be practical.

 

[KPaul]

Many thanks for your reply. I know it would be best to replace the cable and if I get brave enough to tell the missus that I need to lift the carpet and floorboards then that's what I'll do.

However as we just want to get the lounge done I think I will give a local sparky a ring and see what he can do. I don't think the crimped cables will fit back inside this conduit (it is a little tight) so I think it may require another channel being made and extra conduit being used. Can you normally pull cable through a conduit if I twist the wires and pull?

Is what I've done temporarily to the cable safe for the rest of the ring main? Should I refrain from running heavy loads for too long? Surely I've changed the ring into two long spurs? Am I fretting over nothing?

Cheers,
Paul.

 

[Chri5]

The seperated ring, split as is, is 2 x radials which limit the cable to 25a odd.

Not dangerous, but avoid heavy loads such as the iron and hairdrier running at the same time.

Do remember that there is nothing wrong with cable being directly plastered over, subject to correct sleeving of the repair. The conduit is a nice to have, but doesn't have to be there.

 

[KPaul]

I'm trying to get the missus to learn to iron and do her hair at the same time so until she does there's no risk of two heavy load appliances being run at the same time!

If it was to happen would it blow the fuse in the (old style) fuse box or would it overheat the cable itself? I need something to scare the missus with so she doesn't leave the iron on whilst hovering in the electric shower and heating her hairstraighteners up!

I thought the conduit was there to give some space (and subsequently to keep it from overheating) for the cable. I didn't realise it could plastered straight over.

Cheers for all your help mate,
Paul.

 

[Chri5]

The danger lies in the main fuse for the ring being rated at 32a, which when there's a ring is 100% ok.

A 2.5mm cable on a radial can only be rated at a max of 24a odd, so normally a radial is rated at 20a fuse with 2.5mm TE

The issue would be with the cable overheating, since in theory the cable isn't up to taking a 32a load, which the fuse allows.

All other circuits will be fine, and it might be best to strap the damaged cables together to re-build the ring as a temp measure, before undertaking the remedial work. Then the circuit will operate to the 32a design, and fuse rating.

 

[Adam_151]

as part of your temporay measure, you should connect a short length of 2,5 between the two connector blocks to complete the ring

You sure you have conduit in the wall? not just capping?

Which part of nottinghamshire are you in, OOI?

 

[KPaul]

Hi Adam,

I'm in Arnold, off Plains Road.

It's definately conduit, not capping. I've had to break this open to actually get at the cable. I've terminated them for the time being, and worked out that as long as we only use one heavy appliance at any one time then we will come in under 20 amps total. This is safe for now isn't it?

I have noticed that the previous owners may have drilled into it further down so I'm going to rip all the plaster off around the cables and investigate further. This will then hopefully require just crimping a new bit of cable and then cap for extra measure - still a job for the professional.

Are you Nottingham based mate? If so I presuming you're a sparky....how much would you quote for something like this?

Cheers,
Paul.

P.S. I have got some 30 amp terminal blocks (I've used 15 amp until now which should be okay as I'm not drawing anything through it, correct?) and some 2.5 mm t/e cable so I will join them together if I can't get a sparky in the next couple of days.

 

[KPaul]

Sorry Adam, I just saw that you're Lincolnshire based. I'm coming to the Christmas Market this weekend...perhaps you can give me a crash course in crimping whilst I'm there?!

Worth a shot!

 

[sparkybird]

You could get it crimped and sleeved with heat shrink and then you wouldn't need conduit, just be carefull with the filler knife and turn the circuit off when you do it!

Your pictures don't show if there is a socket at the bottom of the cable drop - there needs to be one in order that the cable is running in a safe zone and hence you'd know not to drill there (like the previous owner - NOT!)

SB

 

[Adam_151]

Hi Adam,

It's definately conduit, not capping. I've had to break this open to actually get at the cable.

Round PVC? or oval?

Should be able to pull up and down in the conduit, best ide is to replace the cable fully, next best option is to pull it back into the floor void above, and crimp it and put it in a 'choc box' enclosure

I've terminated them for the time being, and worked out that as long as we only use one heavy appliance at any one time then we will come in under 20 amps total. This is safe for now isn't it?

If you do as you say, then the cable cannot be overloaded, but as it realies on people bearing in mind that things are not as they should be and acting accordingly, then its not foolproof and for what it would take to bang 6' of 2.5 cable in there....

I have noticed that the previous owners may have drilled into it further down

I'd just chip the plaster away where you suspect the damage to be, if it isn't, then I'd leave the plaster on the rest of it and just draw through new cable

Are you Nottingham based mate? If so I presuming you're a sparky....how much would you quote for something like this?

Lincoln...Nah, not a proper one yet... I was just going to say that if you were in say Newark, then I was going to say that you could borrow my crimper over a weekend if you wanted
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