UK Drilled into wire in kitchen

[Dave H99]

Hi all - been an idiot / schoolboy error - drilled into a wire that drops down to a fused spur socket in the kitchen (for washing machine I think) - blew 30A fuse for downstairs sockets and tripped RCD. The wire is behind plasterboard.
Any advice on what the repair should be would be appreciated before I call someone in.
Any idea what this should cost?

 

[davesparks]

Tbh as it's plasterboard, the best, quickest, and easiest would be to pull a new length through using the existing cable and re-terminate each end.

There's no way of knowing from that picture whether a new cable could be pulled in or not.
All we know is that there is plasterboard on the wall, we don't know if it is hollow or dot and dab, whether the cable is fixed in place or free to move.

We also have no idea what is above this room to know whether or not the cable can be readily accessed to replace it.

 

[MJPD29]

Realistically, ideally the cable would be replaced. We all know that's not always possible and a suitable joint can be made, but you'll need to repair the plasterboard after

 

[Julie.]

Oops, I guess I should have looked closely!

I just took a quick look, and from the previous posts, assumed it was between the switch/fcu and the socket outlet.

Yeah, probably not as easy as I first thought.

I would still try to pull it through if it looks possible, but a joint is probably necessary.

 

[littlespark]

A joint, in a suitable box, requiring a larger hole to be made…

Either a new socket in that exact place, or a carefully hung wall calendar.

 

[Markyd]

I cant see how he is going to fix this with a wago box unless there is slack on one of the cables as the wago MF box only has cable entry points at one end and also needs to check if they can be buried or plastered into a wall as i think they have to be in free air......not 100% sure though, before i get roasted

 

[Pretty Mouth]

I cant see how he is going to fix this with a wago box unless there is slack on one of the cables as the wago MF box only has cable entry points at one end and also needs to check if they can be buried or plastered into a wall as i think they have to be in free air......not 100% sure though, before i get roasted

I'd just replace the last 2ft of T+E down to the fused spur with a longer length, but in situations where that's not possible I'd use 2 boxes with a connecting piece to make up the slack.

This all assuming that it's a stud wall BTW, if it's dot n dab, then I'd probably make the repair with crimps.

 

[Midwest]

Although I'll admit to using crimps on 6242y cable (if its that) on rare occasions, alternative jointing method would be preferable, e.g. wago box in ceiling void.

 

[pc1966]

I cant see how he is going to fix this with a wago box unless there is slack on one of the cables as the wago MF box only has cable entry points at one end and also needs to check if they can be buried or plastered into a wall as i think they have to be in free air......not 100% sure though, before i get roasted

It looks pretty certain the cable is going down to the FCU below so replacing the lower bit should be easy even if you can't pull any more down. Junction box would have to be a bit above the drilled hole.

I think the maintenance-free boxes are fine anywhere dry so long as correct Wago type(s) and cable tie are used. It might just be a ring so care needed to get the terminals that are rated 32A in MF box, as from memory there is slight differences among the approved terminals?

 

[timhoward]

Juist been quoted around £70 - Electrician said probably using a Wago box to repair?

I don't think anyone responded to this, even though we got into a lot of discussion!
The price and the solution both sound fine to me, obviously if possible to replace a complete length it's better but the regs allow for a maintenance free joint box to be inaccessible.

It will probably be cheaper to then get a decorator to make good unless you are up for it yourself.
It's perfectly possible to 'hide' a plasterboard repair by putting back the same piece (either with batten and dry wall screws or dot and dab), skimming, and sanding.
The hardest bit is usually matching the original paint colour.

 

[Markyd]

I don't think anyone responded to this, even though we got into a lot of discussion!
The price and the solution both sound fine to me, obviously if possible to replace a complete length it's better but the regs allow for a maintenance free joint box to be inaccessible.

It will probably be cheaper to then get a decorator to make good unless you are up for it yourself.
It's perfectly possible to 'hide' a plasterboard repair by putting back the same piece (either with batten and dry wall screws or dot and dab), skimming, and sanding.
The hardest bit is usually matching the original paint colour.

The regs allow the use of MF boxes but it has to be to manufacturers instructions....I know the hager mf boxes are not suitable for overfilling and have to be in free air just not sure about wago

 

[Spoon]

It might just be a ring so care needed to get the terminals that are rated 32A in MF box, as from memory there is slight differences among the approved terminals?

Not working in the domestic sector, is 32A needed?
I'm presuming its 2.5mm cable. It's not Clipped Direct (27A). I'd say its more Enclosed In Conduit (20A). Ok, it's not in an insulated wall....
Wouldn't the 24A Wago connectors do in this circumstance?

 

[Pretty Mouth]

Although I'll admit to using crimps on 6242y cable (if its that) on rare occasions, alternative jointing method would be preferable, e.g. wago box in ceiling void.

Yeah, I'd prefer to use a wago box, but not always feasible without making a lot of extra work. If it's dot'n'dab sometimes you can pull the cable though the void behind, but if it passes through a couple of blobs of adhesive then you're chasing out the whole run. Same if it's solid plaster.

A lot of solid crimps I have found made by other sparks are not great, and pull apart with little force. However, there is a way of crimping solid conductors that gives a strong, reliable connection, basically by using a tube a size larger, and sliding both conductors the full length of the tube, so they're doubled up, side-by-side. For 2.5mm2, I use a 6mm uninsulated tube. For 1.5mm2 I use a blue insulated tube, and red for 1mm2, flattening out the notch in the middle of the tube with a small screwdriver.

I've tested these to destruction several times and the conductor will snap before the crimp lets go. I've also tested for any increase in resistance, by putting 10 of them in series on a conductor, testing for continuity, then comparing the result with that of an un-cut conductor of the same length. I found the results were identical.

They're useful for things like this, but they are a pain to do, fiddly and time consuming, then you have to make good the insulation and sheath with a tonne of SA tape before plastering.

 

[pc1966]

Not working in the domestic sector, is 32A needed?
I'm presuming its 2.5mm cable. It's not Clipped Direct (27A). I'd say its more Enclosed In Conduit (20A). Ok, it's not in an insulated wall....
Wouldn't the 24A Wago connectors do in this circumstance?

Agreed, after writing this I realised the RFC should only be seeing up to 20A in either leg so anything that is over that should be fine.

 

[mart spark]

Agreed, after writing this I realised the RFC should only be seeing up to 20A in either leg so anything that is over that should be fine.

I think this is technically incorrect, as i thought this a while back, but due to to the potential imbalance of current on an RFC due to length of legs and where high loads are placed, if it were (in the unlikely event) to be pulling more current than say a 24 amp max current rating) of a connector then this isn't acceptable. There's a video on it on Efix i believe as well as one or two others.

 

[Pretty Mouth]

I think this is technically incorrect, as i thought this a while back, but due to to the potential imbalance of current on an RFC due to length of legs and where high loads are placed, if it were (in the unlikely event) to be pulling more current than say a 24 amp max current rating) of a connector then this isn't acceptable. There's a video on it on Efix i believe as well as one or two others.

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