Driilled into power cable @##!!


Whilst putting up a picture I drilled into the wall and hit a sunken 240v power cable going to a 13amp plug socket. It threw the house trip but when I reset it all seems to work okay & the socket works fine (although I haven't the equipment to test it, just plugged a lamp in)
What is the best course of action; + Fill the hole and leave alone (but if I have weakened the cable could this cause a fire?) + Dig out the wall and make a join in the cable (It is right by the front door so anything but a very good filling job will show & what should I use to make the join?) + Lift the carpet and floorboards above and pull a new cable through, making a join in the ceiling void. + None of the above or Move house (only joking!)
Many thanks
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when
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The best and safest way is to replace the cable between the two sockets affected by this damaged section. If you look along the layout of the sockets in the house you should see a pattern of where the cable runs are between sockets. You have to remember that the wiring goes around the sockets in a complete circle, with each socket outlet connected to each the next socket down the line.
Once you get some sort of idea how the sockets are connected to each other, then you can turn the power off and check to make sure. You will need to use a multi-meter with a continuity test function or Ohms (little horse shoe symbol) feature to do the test properly.
Doing the test:
Open a small hole over the damaged part of the cable. Bare off the insulation on the conductors and place the test probes of the meter on the red and black conductors. Undo the sockets at either end of the damaged cable. Connect together the red and black conductors at one socket outlet. With the meter on cont' test or Ohms function you should get a short circuit reading. Now go to the socket again and separate the red and black wires, and the meter should show an open circuit reading. Do the same test with the other socket outlet. This gives you the proper two sockets to replace the cable between.
Test Finished:
Or you could just open the wall up a bit to get access to the damaged area. Then use a couple of crimp connectors to take the rubbed parts out. If you're going down that road, then try to obtain some heat shrink sleeving to fit over the whole of the outer skin of PVC on the cable. Once you've cut the cable to make the new joints, slide the sleeving on one side. The conductors can now be crimped tightly with the proper crimping tool, then slide the heat shrink sleeve over the joint and use a hair dryer to heat it up until it tightens around the cable. This gives the cable a good outer insulation again.
Good luck with it.
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Sorry to be gloomy, but in the time it took the drill to stop - after cutting through onto copper - I'd be amazed if cable was still safe.
Strongly advise you don't ignore it. You may have cut through the cable completely, but cos it's a ring main, everything will appear to work ok. Trouble is, you could now have twice the current flow through the cable :-(
Done properly, and then wall made good, this could be expensive - could this be covered by your insurance policy?
--
Martin

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Twice the current flow ? how come
--
Vass



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Instead of being fed by two 2.5mmT+E (being the 2 "branches" of the ring), one may now be broken. I suppose an analogy is if you need to use a stretch of M25; if there's a blockage, you can go the other way - but so will everyone else so traffic flow on the "unbroken" bit doubles...
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Martin

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Martin wrote:

yup, due to arcing or thinning, so dont. Just use a screw connector to join the cable back together. Youll find the amount of cable available to work with is tight.
Insulate before filling, dont want wet poly on it.

screw con block, aka chocolate block, assuming its indoors

screw block, strip of 12: 70p polyfilla: 1
Youd be mad to get house insurance involved.
NT
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yup, due to arcing or thinning, so dont. Just use a screw connector to join the cable back together. Youll find the amount of cable available to work with is tight.
Insulate before filling, dont want wet poly on it.

screw con block, aka chocolate block, assuming its indoors

screw block, strip of 12: 70p polyfilla: 1
Youd be mad to get house insurance involved.
NT
The OP NEVER said that it is a ring main. The words "house trip" suggest a main switch with a built in RCD.(This is my interpretation of the word house trip but I am not sure what the OP meant)
There are too many variables to give an answer here but here is one scenario.
The socket is a spur from a ring and the OP has created a neutral/earth fault with a metal drill bit that tripped the RCD. The bit was removed and the socket works when a lamp is plugged into it. The drill bit may have severed the earth to the socket when drilling and of course the lamp will still work when power is restored. Everything now "works" and off we go. There would be no earth to the socket supplied by the damaged cable but as the only test was done with a lamp no one will know until it is too late until the socket by the front door is used to power the lawnmover (etc)
Strip connector (insulated or not) buried behind polyfilla or plaster is not an acceptable repair. The cables need crimping (if hidden behind plaster) or replacing.
The circuit may have tripped when you were drilling but now seems to be OK as the metal drill bit is no longer making a short ciruit between the conductors in your damaged cable. The cable is still damaged and need fixing.
If you have good insurance (that will include decorating) then use it. You have paid for it and had an accident. That it what you paid your premium for.
Or DIY. Cheaper, easier and usually better
Adam
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ARWadsworth wrote:

Yes, why not take all that time to make a claim, let them get in some sparks that charge you 150, of which you pay 50 cos of the excess, then you pay more each year because you made a claim. Great idea!
And meantime live without that circuit on for weeks.

i should say. But if the op cant work that out, theres no hope.
NT
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But you felt silly. I did a similar thing, but managed to go through the meter tails between the meter and consumer unit. straight between the live and neutral, taking the insulation off both and BOOM! was I glad my hand wasn't on the drill bit!

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