Which bits do you use heatshrink cable over?

[Al Reynolds]

Hello,

Someone asked a similar question to this back in November, but no-one answered the particular bit I'm interested in.

I'm going to be crimping some 2.5mm T+E together, and will be using the blue 2.5mm butt crimps at:

also want to encase it in heat-shrink sleeving.

Do you just sleeve the individual cores, or the whole cable as well? My instinct would be to put sleeving over each core seperately, then have a big piece of sleeving to cover the lot and keep it together.

Depending on the answer, which of these sleeves do I need?

in advance, Al

[Huge]

I've done the latter - then covered the whole thing with PVC tape.

[fred]

In article , Al Reynolds writes

If you make them up properly, I don't see the need for individual h/s sleeves as the crimps have the insulation flared at the ends to accommodate the insulation on the wire.

of the above, I'd use adhesive lined heatshrink, which is sadly 5-10quid a metre, like code 157-3824 or 157-3903 from

, not a recommended source, just an example, as they are a bit pricey.

Also the RS stuff shrinks 3:1 whereas the tlc stuff only does 2:1 meaning that 25mm will leave a slack boot or you'd need to be v neat to get the lot inside a 12mm piece by eg. staggering the joints in L, N & E.

If you must use the cheap stuff, then perhaps double the cable back on itself (not at the joint) and bind it together with a couple of cable ties as a strain relief.

[Steve Firth]

That's how I've done it, and I've used glue-lined heatshrink for the job mostly because it's much heavier guage than standard heatshrink. I'd reccomend using the glue lined for the cover that goes over everything.

Remember when you apply the final cover to keep it far enough away from the heat source while you are shrinking the individual sleeves and not to attempt to position it until the cable has cooled.

I got into amusing difficulties on the first attempt.

[John Laird]

Are proper junction boxes verboten, now ?

[Genuine question.]

[Al Reynolds]

No, but you must only use connectors where the cable is fastened by a screwing mechanism (e.g. junction boxes, choc-blocks, henley-blocks etc.) if it is going to be accessible later.

If you are burying in plaster or leaving under your flagstone floor, then a 'permanent' connection is required, which means crimps or solder.

The jury is out on whether "under carpeted floor boards" is "inaccessible". In a new house where the boards are the huge chipboard type, I would say that they were inaccessible. In an older house with "plank" boards, I would say it was accessible if the floorboard can be lifted without lifting more than one carpet.

In my own house I only have junction boxes under floorboards under "walkway" areas - doorways, hallways and landings - places were no furniture is "likely" to be placed. This way they are "accessible".

Any which are just joining up two bits of cable, I am planning to replace with crimped connections.

HTH, Al

[John Laird]

Thank you for the illumination. The light bulbs in my head remained obstinately off while I tried in vain to think of circumstances where I would want to crimp.

Even in your genuinely inaccessible areas, I would still wonder whether some re-wiring wouldn't be better than jointing, which would often remain unsuspected.

[Dave Plowman]

Those type of crimps are already insulated, so if you make sure you only bare the correct length of conductor will be perfectly safe elecrically. So all you really need is mechanical protection to replace the outer sleeve.