Joining a cable to be buried in a wall

[SJD]

Now and again, I need to join a cable that is buried in a wall, sometimes in a stud wall, sometimes to be plastered over. Sometimes when someone has drilled through it (last one was a kitchen fitter who should have known better), or sometimes to extend a cable e.g. to move an accessory lower on the wall. Generally I'm thinking of 2.5mm2 or 1/1.5mm2 twin & earth. And assuming a new cable can't easily be pulled through.

What jointing method do people prefer?

I've used heatshrink crimp butt connectors plus an outer covering of glue-lined heatshrink. I worry about the crimp not gripping one of the conductors tightly enough and it coming loose.

I've also used heatshrink solder connectors, again with an outer glue-line h/s covering. If the copper is not clean enough, I worry about a dry joint to one of the conductors.

And what if one cable is new solid T&E, while the other cable is stranded imperial cable?

 

[Pete999]

Now and again, I need to join a cable that is buried in a wall, sometimes in a stud wall, sometimes to be plastered over. Sometimes when someone has drilled through it (last one was a kitchen fitter who should have known better), or sometimes to extend a cable e.g. to move an accessory lower on the wall. Generally I'm thinking of 2.5mm2 or 1/1.5mm2 twin & earth. And assuming a new cable can't easily be pulled through.

What jointing method do people prefer?

I've used heatshrink crimp butt connectors plus an outer covering of glue-lined heatshrink. I worry about the crimp not gripping one of the conductors tightly enough and it coming loose.

I've also used heatshrink solder connectors, again with an outer glue-line h/s covering. If the copper is not clean enough, I worry about a dry joint to one of the conductors.

And what if one cable is new solid T&E, while the other cable is stranded imperial cable?

Wagos

 

[SJD]

I've left a Wagobox in a stud wall a few times, but not always practical when there is not enough slack in the cables (the cables all enter one end in the standard Wagobox).

But actually, is there anything to stop me burying a Wagobox in a solid wall and plastering over? I've never thought of doing that.

 

[Pete999]

I've left a Wagobox in a stud wall a few times, but not always practical when there is not enough slack in the cables (the cables all enter one end in the standard Wagobox).

But actually, is there anything to stop me burying a Wagobox in a solid wall and plastering over? I've never thought of doing that.

Dunno mate, but that's a right rough old job imo

 

[Gavin John Hyde]

well if the cable is tight and not much slack available to join, then why not add a extra section in ... say 3 or 4 inches. you will then have 2 joins but at least you got the slack to do a good job of it.
In terms of tightness after crimping, give it a tug and if it comes loose, its no good. if all holds firm then move onto the heat shrink/wrap.
There is only so much you can do before you replace who sections of cable.

 

[Midwest]

In a scenario of cable being drilled into for example, as a last resort the cable can't be replaced, joint can't be left above wall unit etc (Wago), I've used butt connectors & heat shrink, as you've suggested. I bought some of these, but not used them yet;

They'll be some arguing against using crimp connectors on solid cables, but I've seen that disputed on another forum.

PS Lets not have any book shelf jokes

 

[Bobster]

Nothing wrong with using crimps on solid core conductors, so long as they are the correct suitable crimps and crimp tool to match.

Usually they come un-insulated and need an indent style crimp tool.

 

[davesparks]

Chop a box in to the wall and make the joint in there, put a blank plate over it.

 

[Dave OCD]

You could also sink in a small weatherproof box and use Wagos or similar within, really it would have to be within a safe zone though, not that anybody other than Sparks' know the slightest thing about them.

 

[Leesparkykent]

Ideal SpliceLine In-Line Wire Connectors Pack of 10 - http://www.screwfix.com/p/ideal-spliceline-in-line-wire-connectors-pack-of-10/42201?tc=UA4&gclid=CjwKCAjw8IXMBRB8EiwAg9fgMMC5bZQx9nkRlCzGy2bhq4kNiU68RBD4nuIFrr9jlGvBMQu4GWYpzxoCjc0QAvD_BwE&gclsrc=aw.ds&dclid=COepqMCvudUCFYnjGwod3tIFFA Use these...stagger them and heat shrink.

 

[Ian1981]

Speaking of heat shrink, can anyone recommend a decent heat gun which isn't mains fed?

 

[LankyWill]

Get a map torch, ideal for stripping armoured/ Hi Tuff in the winter.

 

[bigspark17]

Why not replace the cable or put a mf joint under the floor or ceiling above/below where the cable is damaged to the accessorie?

 

[Rpa07]

I always have a kit with through crimps, I then solder, then individual heat shrink, then complete heat shrink, staggering the joints to make it neat.
I find that I can walk away and not think of high resistant joints etc - plus I really enjoy the practical part of it.
I would consider adding a length if required or even adding in a chopped in box. Anything to get the job done right if a new cable is not possible.

 

[SJD]

I always have a kit with through crimps, I then solder, then individual heat shrink, then complete heat shrink, staggering the joints to make it neat.

Are these unsleeved crimps that you solder by heating and manually by feeding in solder, or are they some assembly with a solder ring, a bit like the photo posted by Midwest but with a crimp section as well?

 

[Rpa07]

Own solder fed in. I originally took the insulation off of insulated butt crimps and soldered because I didn't trust the crimp itself, now I've got so used to the 'ritual' that I just get on with it. I found a good source of non insulated through crimps.
To the other question, I use a creme brule blowtorch to shrink the wrap. Have to be a bit careful in tight spaces but may try a heatgun in future.

 

[Rpa07]

Own solder fed in. I originally took the insulation off of insulated butt crimps and soldered because I didn't trust the crimp itself, now I've got so used to the 'ritual' that I just get on with it. I found a good source of non insulated through crimps.
To the other question, I use a creme brule blowtorch to shrink the wrap. Have to be a bit careful in tight spaces but may try a heatgun in future.

 

[Rpa07]

Own solder fed in. I originally took the insulation off of insulated butt crimps and soldered because I didn't trust the crimp itself, now I've got so used to the 'ritual' that I just get on with it. I found a good source of non insulated through crimps.
To the other question, I use a creme brule blowtorch to shrink the wrap. Have to be a bit careful in tight spaces but may try a heatgun in future.

I think I've been sucked into the double post issue! It posts but leaves the post to make you think it hasn't been. I thought you were all just careless!

 

[Rpa07]

Oh no, it ended up three! I'm so embarrassed!

 

[SJD]

Thanks for all the replies. I perhaps should have clarified that my question was for when it is not easy to access the floor/ceiling void and the customer doesn't want an extra blanked-off accessory box.

I agree with Pete999 that burying a Wagobox under plaster would be rough old job, perhaps why I'd not thought of doing so.

I hadn't thought about enclosing the SpliceLine connectors in some heatshrink, not sure that is also not a bit rough too.

The connectors in Midwest's photo, I've used quite a few times, generally successfully though is it possible to burn the sleeving if too enthusiastic with the heat gun.

As an aside, I thought after a new post I was going to loose the irritating ad at the top of every page, but it still malingers there ...