Hi. Reassure me! Kitchen wiring damaged!

[simch]

Hello. Sorry for the long post, my first or second I think! I am looking for reassurance, I can hardly believe what has happened yesterday. After nearly 2 years, (seriously), I finally got our kitchen fitters back to finish off the final snags and jobs in the kitchen, (the wife has been very very patient!)
Kitchen fitter is Part P registered and I would genuinely say very good ability wise, (used him before), delays have been due to his very busy schedule and a bit of a disagreement I had with one of is guys who bodged some plumbing very badly! PArt P guy was on site yesterday along with one of his guys, litterally the final job was to secure a custom built cupboard to the wall in the corner next to Fridge freezer, (litterally last job after 2 years!). .......Kitchen guy fitted and l bracket to the top, marked it, drilled into the wall, fitted rawlplug, drilled the second marked hole, found some as he described "resistance" and BANG, I just saw a flash from the cupboard and the guy screemed......RCD tripped..

He turned it back on, everything worked, but the trip to the hob was off, turned that back on and it worked, but this was the damaged cable.

When they wired it, they wired two 32 amp (I think, cooker cable anyway)supplies, one to the electric hob one side of kitchen and another the the double ovens on the other side. ONly the hob one is damaged, the Kitchen fitter boss (part P) was offsite on his way home with the cheque, when it happened, His guy stayed and dug out the plaster, found the damaged the drill went dead centre trough the cable and shorted live to earth, the neutral is untouched. Also the earth is intact, not even a mark, I think the drill bit made the connection, flash and off it went.

This is inside a backless cupboard, so they say they can repair it with a connector inside an inspection cover, either recessed in or surface mount. The boss returned and temporarily fixed it using a huge choc box connector (60 amp he said), but he ONLY repaired the nicked live wire, the damaged was very small, only one "strand" was knicked and not cut through, but he snipped it through and reconnected it. He manged to pull enough cable through to fit a surface mount if needed, but when i called him this morning, he said one option if to just repair the knicked live, ie fit the cable into an inspection cover and fit one terminal connector to the ONE damaged cable, leaving the others intact, sort of bypassing it but within the box....
Now I supose this makes sense to me, if the other cables are undamaged why cut them, but it just seems a slightly messy way of dealing with it.
I would agree with them that to replace the whole lot is a massive amount of work and will dsiturb a lot of compelted work including a very expensive floor so I have no problem having a permenant repair, it will not be on show after all.
I read on here last night about crimping it and heatshrinking it, whihc I presume is possible on just theone cable, but would their solution of a terminal block or connector box, with just the damaged (now cut) cable routing though it be OK.

Sorry to rattle on, but it has been very expensive so far, we have run into lots of trouble, and to have it go wrong litterally right at the end just does my head in.

Any reassurance and advice is greatly appreciated. I do trust these guys, but also know how busy they are, how difficult it was to get them back to finish and not they have been paid, I want to make sure that any solution is firstly legal and suitable.

ONly other thing I should mention as it may complicate thigs is there is a water fitler for the fridge freezer icemaker fitted in the same cupboard. Would this mean any cable repar needs to be outside the cupboard, ore buried in plaster, or will a surface mount be ok. Do they need to do any additonal waterproofing?

They are good guys I am sure, it was a careless mistake at the end of a long day, so i can forgive them that, but I need it fixing satisfactorily.
Cheers

 

[fattony]

They should be re terminating the damaged cable into a junction box which remains accessable, have they issued a certificate for the works or are you awating that?

 

[Click-Sure]

Looks the boss needs to induct his elves into the permitted wiring zones for concealed fixed wiring. (assuming your kitchen has been wired up correctly.

If there is, as you say, sufficient slack on the cable for a junction box of sorts then there will be room to use through crimps. Problem is, just crimping the damaged phase (live) wire is difficult as heatshrink slides over the whole cable, so it would mean crimping all three conductors.

As long as the cable passes a simple 500v insulation resistance test, all should be well.

 

[simch]

They should be re terminating the damaged cable into a junction box which remains accessable, have they issued a certificate for the works or are you awating that?

Cheers.
Still awaiting the issuance, they tested it all last week!
He was due to bring it yesterday but had not done it.

But when you cable, do you mean the single "live" cable that is the only one damaged or the whole three core "cable". Ie, should he be cutting though the other two undamaged cores and connecting the whole lot in a suitable inspectable terminal box?

I just read some other post about dmage to the cable sheath through the carbon that comes from the flash. It may well be he needs to trim the cable back to remove such damage anyway. At the moment it is temp fixed with just the live core very neatly removed from the gret insulating sheath, the other two still within in, but surely the other two will need to be cut, terminated in an approved connector. Otherwise, they they run though the surface moutn box, they will only have their own core shethign as protection, and the earth will have nothign....?
I am pretty sure I did not misunderstand him when he said he could just reminate the singel damed live core off, and leave the others....? It just "sounds" wrong to me.....!

MAybe I am worrying too much, I should just let him get on and do the certificate. But I do worry!!

 

[JohnD]

it could be crimp-joined and heat-shrink sleeved. That would be permanent and could be plastered over.

edit: too slow

 

[simch]

Looks the boss needs to induct his elves into the permitted wiring zones for concealed fixed wiring. (assuming your kitchen has been wired up correctly.

If there is, as you say, sufficient slack on the cable for a junction box of sorts then there will be room to use through crimps. Problem is, just crimping the damaged phase (live) wire is difficult as heatshrink slides over the whole cable, so it would mean crimping all three conductors.

As long as the cable passes a simple 500v insulation resistance test, all should be well.

I think he gave him a bit of a roasting, although the guy was visibly very shaken by the bang and flash! He was very grey and definately shaking afterwards! But I think boss feels quite emabrrased by it all too.

Excuse my total ignorance but could they fit another cooker isolator switch in there? Or is that not necesary ? Its just there is a spare, screfix sent three and we only needed two!! It is single switch too, not a switch and three pin plug?

This would just mean there were two isolation points on the hob circuit. Is that allowed? If so, would that be more of a bodge than an inspection cover and terminal box?

 

[simch]

it could be crimp-joined and heat-shrink sleeved. That would be permanent and could be plastered over.

Cheers. That means all three cores being cut and crimped, to fit the heat shrink?

Would that be the best option in your opinion, I am thinking as there is also water in the same cupboard..

 

[JohnD]

the damaged core could be joined with a crimp with its own heat-shrink (they are a bit more expensive but a great invention).

the whole lot has to be covered with something equivalent to the sheathing. I'm not sure if capping or self-amalgamating tape would be acceptable. If not, the wall would have to be chased out deeper to take the bundle of crimps.

If the cable is under capping, a new piece could be slid through and the jointing done where there is more room.

someone may have a better idea.