Repairing insulation

well the QI klaxon answer is 'insulation tape' , it should not, though in practice it will probably be fine. It also rather depends if the metal is also damaged - clearly more than just a scratch, and it should be cut and rejoin, ideally with glue lined heatshrink sleeve over the top.

If you have room then there are various types of crimps and terminals, if it is in an accesible box you could use choc block or a wago.


If the metal is OK, and you can lift an end, and can thread some sleeving on, that may  be OK, self amalgamating tape can be OK in the right circumstances,  but not haphazardly applied in a lumpy blob, you need good access, at which point you can usually do better.

Mike

Acceptable in my view to repair the insulation, and arguably preferable to use of a through crimp. In my experience, a significant number of faults on existing installations are due to failed crimp connections.


For larger conductors self amalgamating rubber tape is useful, not easy to apply neatly to smaller conductors, in which case I prefer heat shrink, two layers in most cases.


It would be better practice in my view to replace the damaged wire or cable, but this is sometimes unreasonably costly or disruptive.

A small piece of damaged cable sheath can be repaired with good quality P.V.C. insulation tape.. BUT these days the quality of that is very poor in many cases and it may have carp glue, thus allowing the tape to come loose over time, especially if used in warm conditions. If  possible the section could be oversleeved. If the damage is very bad replacement of the damaged cable will be required. If there is sufficient space the cable can be cut through and a junction box (joint box) used to re-terminate. You have not specified the cable size or type.


Z.

PIB (polyisobutadiene) tape is an excellent material but must be adequately stretched to amalgamate properly, which is tricky on small conductors. Adhesive heatshrink is also very good, both methods have insulation far exceeding that required for safety. I wouldn't fit crimps to small conductors < 4mm, as the crimps do not distort the conductors sufficiently and are not reliable over time. Z, fish glue on PVC tape is clearly useless, although I agree with your sentiment!

I would buy it from CPC. With Ebay you never know where it came from!

3m are offering an Ethylene Propylene Rubber tape, same properties just a bit newer type.

There are slightly cheaper ones which are also fine.
cpc.farnell.com/3m/scotch-23/scotch-23-self-bonding-tape-19mm/dp/CB00032?st=self amalgamating tape

See data sheet for full details (on poage)

Oh yeah sorry guys was 2.5 mm pvc armoured. Looked as if someone had ran a knife down it. So a chocky block is acceptable I know some electricians hate using them ?. But I take it crimping or sleeving is best practice?

For small cable like that I would favour two layers of heat shrink. But choc block or crimps are in my view acceptable.

Thank you guys

Keep in mind that if you cut and re-join the conductor, BS 7671 then requires the joint to be enclosed in a suitable enclosure - which heat-shrink, tape etc alone I suspect wouldn't suffice.

   - Andy.