Stripping Outer & Inner with 25mm Cable

Careful_Bodger · 10 Dec 2004

Just out of interest, what is good practice for stripping the somewhat robust outer insulation on 25mm2 cable tails? How far should the outer go into a CU, for example?

I have already seen from other posts that the inner insulation should not leave any copper exposed.

Also, what cutting techniques are appropriate, particularly to prevent nicking the inner insulation when stripping the outer? Is there an equivalent tool to that which I use on T&E? (It must be a biggie if there is one!)

TIA for everyone's helpfulness - it has been V. interesting here lately.

brown-nought · 10 Dec 2004

I use heavy duty wire cuuters but a sharp stanley knife works just as well. Don't try and cut all the way through, a gentle repeated circular score works well.

There should be no bare wire outside the terminal.

dingbat · 11 Dec 2004

The grey outer sheath, which counts as mechanical protection for visible cables, only needs to enter the enclosure far enough so that it won't pull back out.

What I do is strip both layers of insulation back by about an inch or so then strip (carefully, with a Stanley knife) about 10mm of grey off so that the inner insulation colour is visible. Then I pass the tails into the CU before making the U-bend to fit to the main switch. As you bend the cable the conductor cores will slide over each other so the end is uneven - but as there's a decent bit of copper exposed it is simple then to get your shears in and crop it to length. It's neat and it means that you're not trying to strip insulation in a confined or awkward space.

Incidentally, I always strip the CU down to just the case, which I then mount in place. Then I run in the tails and main earth and equipotential bonding conductors before replacing the DIN rail and isolator/RCD. The I connect the tails and draw in all the (labelled)circuit conductors in the right order for their relevant circuit breaker.

Hope that helps

Careful_Bodger · 11 Dec 2004

...for your very clear and useful reply

dw3101 · 11 Dec 2004

Agree with above comments.. I run a score around with a knife and then cut down from score to end of cable to help split it off..

I then Put the bend in with a pair of pliers on the end of the cable then cut that bit off

I use cable cutters to trim the red or black and then square the end off..

Hardest part is making both bends look the same and neat

just make sure when doing other end of the cables you dont rip the main sw / rcd off the rail

David

Lectrician · 11 Dec 2004

Dingbat has described it 100% the way I, and most others i expect, would do.

It's funny the things you take for granted.

ban-all-sheds · 12 Dec 2004

Careful_Bodger said:
Just out of interest, what is good practice for stripping the somewhat robust outer insulation on 25mm2 cable tails?

You could use your teeth.

Well.... some people could.......

securespark · 12 Dec 2004

Leave a small portion of inner showing (for id) inside the CU, but not outside (ie where the tails enter the meter)?

Some have knocked me in the past for showing the inner where DI tails are outside the CU. My way of thinking is that it is useful to id the colour at all points of connection, not just inside the CU.

Lectrician · 12 Dec 2004

securespark said:
Leave a small portion of inner showing (for id) inside the CU, but not outside (ie where the tails enter the meter)?

Some have knocked me in the past for showing the inner where DI tails are outside the CU. My way of thinking is that it is useful to id the colour at all points of connection, not just inside the CU.

Thats what coloured tape and heat shrink id for

dingbat · 12 Dec 2004

Lectrician said:
Thats what coloured tape and heat shrink id for

The recs cable jointers use small red and black tie-wraps for identification. Obviously, when they get around to it they'll start using brown and blue.

Lectrician · 12 Dec 2004

Our rec use tape or sleeve. They are already using new colours, and THEY put a sticker at the origin similar to ours.

dw3101 · 13 Dec 2004

Leaving the inner showing outside of the CU would be breaking regs would it not??

I also think it looks untidy.. Our REC, strip the cable right through to the conductor leaving no colour visible then fit those little grey ends and two red cable ties.

David

plugwash · 13 Dec 2004

it would seem far mroe sensible to me to put the red and black on the outside and the grey on the inside

double insulation in itself is mainly done so that damage will become visible before it becomes dangerous

Lectrician · 13 Dec 2004

You can get double insulated with coloured outer.

plugwash · 13 Dec 2004

does the double insulated with coloured outer have a grey inner?

two layers of the same colour would seem to default the point of double insulation.

diynot

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Stripping Outer & Inner with 25mm Cable

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