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Discuss Joining a cable to be buried in a wall in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. SJD
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    SJD Trusted Advisor

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    Braccan heal
    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?
     
  2. Pete999
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    Pete999 Trusted Advisor

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    Wagos
     
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  3. SJD
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    SJD Trusted Advisor

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    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.
     
  4. Pete999
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    Pete999 Trusted Advisor

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    Dunno mate, but that's a right rough old job imo
     
  5. Gavin John Hyde
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    Gavin John Hyde the lights are on but nobody is home

    Location:
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    Sulis Electrical Services
    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.
     
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  6. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    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;
    upload_2017-8-2_13-15-58.jpeg

    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 :)
     
  7. Rob
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    Rob Trusted Advisor

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    North west
    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.
     
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  8. davesparks
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    davesparks Trusted Advisor

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    guildford
    Chop a box in to the wall and make the joint in there, put a blank plate over it.
     
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  9. Dave OCD
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    Dave OCD Electrician's Arms

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    Hendry Electrical Services
    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. :)
     
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  10. Leesparkykent
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    Leesparkykent You Rock Gmes Staff Member Trusted Advisor

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  11. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Speaking of heat shrink, can anyone recommend a decent heat gun which isn't mains fed?
     
  12. LankyWill
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    LankyWill Electrician's Arms

    Location:
    Northants
    Get a map torch, ideal for stripping armoured/ Hi Tuff in the winter.
     
  13. bigspark17
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    bigspark17 Electrician's Arms

    Location:
    wales
    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?
     
  14. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

    Location:
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    Ebenezer electrical
    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.
     
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  15. SJD
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    SJD Trusted Advisor

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    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?
     
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  16. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

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    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.
     
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  17. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

    Location:
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    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.
     
  18. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

    Location:
    Bristol
    Business Name:
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    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!
     
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  19. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

    Location:
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    Oh no, it ended up three! I'm so embarrassed!
     
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  20. SJD
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    SJD Trusted Advisor

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    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 ...
     
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  21. Rpa07
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    Rpa07 2000 posts - only 46379 behind Telectrix! Electrician's Arms

    Location:
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    Business Name:
    Ebenezer electrical
    We don't mind an ulterior motive @SJD@SJD - it's amazing how you look past the ads as if they are supposed to be there.
    Ps I've never written ulterior before in my life, took me a good 30 seconds to spell it and that's with the tech!
     
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  22. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Can I be less popular ? ... heat shrink is great, but if it's the stuff I think we all use, as far as I know its not BS rated for cable insulation. Doesn't mean it doesn't work, but 2 layers of heat shrink is not the same insulation as a BASEC 6004 cable (624Y for example). So I think the joint still needs a containment ... I can hear rocks hitting the roof already o_O
     
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  23. SJD
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    SJD Trusted Advisor

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    Braccan heal
    Thanks, I'll perhaps give this a try next time.
     
  24. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Interesting point, I'd have to look at the label the next time I buy some to see what it is or isn't approved to.

    DNOs make extensive use of joint kits which are insulated and sheathed with adhesive lined heatshrink somclearly a suitable product exists,
     
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  25. wirepuller
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    wirepuller Trusted Advisor

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    south uk
    Personally I would never bury a joint of any sort in the wall. I always either replace or use a flush box and blank plate.
     
  26. SparkyChick
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    SparkyChick Making a banana smoothy for my fave gorilla Electrician's Arms

    Location:
    South Wales
    Business Name:
    SparkyChick
    If you're soldering and you're concerned about dry joints caused by dirty or oxidised cables, get yourself a flux pen and dab a little on the copper before soldering. Can help immensely.
     
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  27. SparkyChick
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    SparkyChick Making a banana smoothy for my fave gorilla Electrician's Arms

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    SparkyChick
    And a side note about using blowtorches... make sure your insurance covers you for using them. When I took out mine, I was asked about hot tools, which included blowtorches, and whether I used them. I have a heat gun for shrinking which doesn't fit the hot tool category because it doesn't use flame.
     
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  28. SJD
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    SJD Trusted Advisor

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    Braccan heal
    Is this the same as the tub of flux I use whenever I do a bit of home DIY plumbing and solder some copper pipes?

    I did once try to use a small blowtorch with an attachment but didn't get it to work properly, so I stick with an electric heat gun, which I much prefer. The only downside is the times when there's no convenient socket nearby due to the work underway!
     
  29. SparkyChick
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    SparkyChick Making a banana smoothy for my fave gorilla Electrician's Arms

    Location:
    South Wales
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    SparkyChick
    Not sure about chemical composition, but I suspect the paste is somewhat more aggressive. The flux pens I use are designed for printed circuit board work, like mounting surface mount devices in hot air rework scenarios.

    Granted if the whole house is off it's a bit tricky, but my long extension lead and heat gun travel together :)
     
  30. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Thanks for that SC ! I was practicing my "really Sir, it's just my hair dryer" speech but it looks like I can bring it out of the closet now :)

    No Westie, the heat gun, the heat gun ...
     
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  31. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    My household insurance allows me to use one of these Master Class Deluxe Gas Kitchen Blow Torch Professional Cooks * Brand New * | eBay - https://www.ebay.co.uk/i/192097300088?chn=ps&dispItem=1&adgroupid=45192390362&rlsatarget=pla-331477173012&abcId=1129006&adtype=pla&merchantid=114891207&poi=&googleloc=1007245&device=c&campaignid=861899495&crdt=0 for my crème bulee. I just take the joint to my house, sorted :rolleyes:
     
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  32. SparkyChick
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    SparkyChick Making a banana smoothy for my fave gorilla Electrician's Arms

    Location:
    South Wales
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    Yes, it's a pain in the posterior, I've nearly fallen foul of it a few times. You click 'Post Reply', the little spinner widget appears in the top right corner to show it's working and then it just stays there. Maybe the scripts are timing out on the server or something?

    (@Dan@Dan - Just to let you know, if you didn't already, there is an issue with posting)
     
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  33. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    This worked for the Apollo 13 crew
    upload_2017-8-3_9-40-54.jpeg
     
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  34. DPG
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    DPG Electrician's Arms

    Location:
    S Yorkshire
    At least it has been PAT tested!
     
  35. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    The only thing I use a blowtorch is for roasting marshmallows :)
     
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  36. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    Also crème bulee and when you have no electrickery :)
     
  37. Des 56
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    Des 56 Trusted Advisor

    Location:
    Gliese 581C
    If your happy with the crimped or soldered joint,you could use a short length of plastic pipe to cover the joint,put adaptors on the ends to enable a stuffing gland to act as support
    Personally I would be reluctant not to have a box and blank plate for enclosing the joint
     
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  38. Pete999
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    Pete999 Trusted Advisor

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    Northampton
    Is the damaged cable a switch drop or socket? Sorry just read the opening post, personally I would avoid joining if I could, if you are going to dig a dirty great hole in the wall to repair a cable, I would go the whole hog and replace the entire piece to where you can effect a decent MF joint that wont need burying in the plaster, I appreciate it's allowable, but not my cup of tea I'm afraid.
     
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    Last edited: Aug 3, 2017
  39. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    There are times when there is no alternative, but to 'bury' a crimped or soldered joint. I did such when a chap drilled into cable above socket. Flat roof extension, filled with Celotex with no space for JB.

    He was in the process of putting up a picture frame, we could of turned it into a bookshelf, I suppose :eek:
     
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  40. SparkyChick
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    SparkyChick Making a banana smoothy for my fave gorilla Electrician's Arms

    Location:
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    I suppose a small length of conduit with a couple of adaptors and glands on the end would be a good choice.

    That's a nice idea and a great tip. Thanks :)
     
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  41. davesparks
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    davesparks Trusted Advisor

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    Whereas the hot works section of my insurance does include hot air guns, the only thing it does not include is a soldering iron.
     
  42. SparkyChick
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    SparkyChick Making a banana smoothy for my fave gorilla Electrician's Arms

    Location:
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    Business Name:
    SparkyChick
    So much variation. Pays to check the fine print and ask lots of questions :)
     
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