Hi. I want to extend some (2.5mm2) cable and intend to crimp the connections (using a proper ratchet tool, before anyone says!). The crimps will then be buried in plaster.
I'll be using the insulated blue butt crimps but would like to know if extra protection is needed around them before sloshing wet plaster over them.
Cheers
Some heatshrink sleeving covering the whole joint would do no harm.
I always thread cables in oval trunking, and crimps are fine in that. You stagger them to avoid a single bulbus lump. If they're directly embedded in plaster and it were to ever get damp, you'll end up with a hard to diagnose RCD tripping problem.
. . . Thanks chaps. I'll go for the oval as I've already got some somewhere.
You need two layers of insulation - one round the wire (the insulated crimp takes care of that), and a second overall sheath. If your cable is not in plastic trunking of some sort then heatshrink tubing is the easiest way to do it.
Simple and cheap. But bear in mind what Mr Gabriel said about damp and untraceable RCD trips. I'd be tempted to put a squodge of silicon in each end of the oval.
Dave Liquorice coughed up some electrons that declared:
And don't forget that unset silicone sealant is quite conductive, should one get a bit over liberal with it ;->
Bit of tape round each end might be another solution to keeping wet plaster out.
Cheers
Tim
For me, adhesive lined heatshrink makes the ideal finish, you are reinstating the continuous water resistant (proof?) sheath on the cable.
Yup, that works nicely, although possibly overkill in many situations. (the ordinary stuff will make a nice tight seal on the cable if you extend it past the joint a couple of inches each way).
If you need to improvise adhesive lined heatshrink, then shaving a few slithers off a hotmelt gluestick and slipping them inside the tube alongside the cable before you shrink it also works well. As you heat it to shrink the tube the glue melts and flows round the inside.
True for the plastering, I like it for the strain relief on joints that aren't going to be buried.
Nice improv & dismount, I'll keep that in mind for when I can't find the lined stuff. How about gooping with hotmelt then applying the sleeving and shrinking to re-melt?
Yup, that works as well... I have a mini blowtorch kit I got from maplin many years back, that has a glue gun attachment. The attachment I never seem to use, but the dinky glue sticks that came with it are ideal for this sort of thing - just heat the end of one, and wipe it down the wire to deposit some gloop.
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