A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. But mainly to save
effort in future (particularly where there isn't much spare left to re-
strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

2. Similarly, will overtightening terminals such that the wire is
crushed be a problem, so long as it is not actually broken?

A test with a multimeter showed negligible/no change in resistance
where I did this deliberately to a small length of test cable so I'm
inclined to say "not a problem" - but am I right?

Thanks

Neil

On Jul 26, 12:56*pm, Neil Williams wrote:
A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. *But mainly to save
effort in future (particularly where there isn't much spare left to re-
strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

The problem here is not the increase in resistance (negligible as you
say), but that nick will act as a stress concentrator, meaning that
the wire is much more likely to snap at that point - particularly if
it is flexed at all.

2. Similarly, will overtightening terminals such that the wire is
crushed be a problem, so long as it is not actually broken?

I don't think that is a problem (but an expert will be along shortly
to correct me). In fact, I would have thought some deformation of the
wire was required, to ensure a nice gas-tight contact.

In article
,
Neil Williams wrote:
A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. But mainly to save
effort in future (particularly where there isn't much spare left to re-
strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

It would depend on the size of the 'nick'. A mere scratch could be ignored
- something that reduces the diameter appreciably best not. But given
there are lots of devices around for stripping cable properly, it
shouldn't be a question which needs asking.

2. Similarly, will overtightening terminals such that the wire is
crushed be a problem, so long as it is not actually broken?

No - as the cross section remains the same.

A test with a multimeter showed negligible/no change in resistance
where I did this deliberately to a small length of test cable so I'm
inclined to say "not a problem" - but am I right?

You'd need a very specialised meter to measure this sort of very low
resistance.

Neil

--
*Do infants enjoy infancy as much as adults enjoy adultery?

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman wrote:
It would depend on the size of the 'nick'. A mere scratch could be ignored
- something that reduces the diameter appreciably best not. But given
there are lots of devices around for stripping cable properly, it
shouldn't be a question which needs asking. *

I tend to use a small blunt kitchen knife for cable stripping,
it cuts the PVC without making any impression on the copper
underneath. Taught to me by my sparks instructor 20 years ago.

JGH

Dave Plowman (News) wrote:
In article
,
Neil Williams wrote:
A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. But mainly to save
effort in future (particularly where there isn't much spare left to
re- strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

It would depend on the size of the 'nick'. A mere scratch could be
ignored - something that reduces the diameter appreciably best not.



But given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

--
Adam

ARWadsworth wrote:

Dave Plowman (News) wrote:

Neil Williams wrote:

If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

Surely you'd need to snip through 1, 1.5 and 2.5 mm^2 live cables to
form the correct sized notches for everyday use?

Andy Burns wrote:
ARWadsworth wrote:

Dave Plowman (News) wrote:

Neil Williams wrote:

If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to
cause enough difference to the resistance of that core to make it
unsafe?

given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

Surely you'd need to snip through 1, 1.5 and 2.5 mm^2 live cables to
form the correct sized notches for everyday use?

I have an apprentice.........

--
Adam

ARWadsworth wrote:

Andy Burns wrote:

Surely you'd need to snip through 1, 1.5 and 2.5 mm^2 live cables to
form the correct sized notches for everyday use?

I have an apprentice.........

Lets hope he learns before he moves onto 4, 6 and 10 mm^2 cables

jgharston wrote:
Dave Plowman wrote:
It would depend on the size of the 'nick'. A mere scratch could be
ignored - something that reduces the diameter appreciably best not.
But given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

I tend to use a small blunt kitchen knife for cable stripping,
it cuts the PVC without making any impression on the copper
underneath. Taught to me by my sparks instructor 20 years ago.

It takes too long. Any anyway, the kitchen knife is for changing plugs.



--
Adam

ARWadsworth wrote:
I tend to use a small blunt kitchen knife for cable stripping,
It takes too long. Any anyway, the kitchen knife is for changing plugs.

The angle grinder wasn't to hand.

JGH

On Tue, 26 Jul 2011 16:00:22 +0100, ARWadsworth wrote:

Dave Plowman (News) wrote:
In article
,
Neil Williams wrote:
A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. But mainly to save
effort in future (particularly where there isn't much spare left to
re- strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

It would depend on the size of the 'nick'. A mere scratch could be
ignored - something that reduces the diameter appreciably best not.



But given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

Yes, I have a pair of those. Had them for 45 years...



--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

Bob Eager wrote:
On Tue, 26 Jul 2011 16:00:22 +0100, ARWadsworth wrote:

Dave Plowman (News) wrote:
In article
,
Neil Williams wrote:
A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. But mainly to
save effort in future (particularly where there isn't much spare
left to re- strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to
cause enough difference to the resistance of that core to make it
unsafe?

It would depend on the size of the 'nick'. A mere scratch could be
ignored - something that reduces the diameter appreciably best not.



But given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

Yes, I have a pair of those. Had them for 45 years...

Bedded in on some imperial 7/.029 T&E then:-)

--
Adam

On Tue, 26 Jul 2011 17:44:07 +0100, ARWadsworth wrote:

Bob Eager wrote:
On Tue, 26 Jul 2011 16:00:22 +0100, ARWadsworth wrote:

Dave Plowman (News) wrote:
In article
,
Neil Williams wrote:
A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. But mainly to
save effort in future (particularly where there isn't much spare
left to re- strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

It would depend on the size of the 'nick'. A mere scratch could be
ignored - something that reduces the diameter appreciably best not.



But given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

Yes, I have a pair of those. Had them for 45 years...

Bedded in on some imperial 7/.029 T&E then:-)

It was actually some heavy duty rubber insulated flex feeding lighting
battens on a stage. I was hanging on to the (earthed) stage framework
with the other hand/arm, 30 feet up, at the time.



--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

In article ,
ARWadsworth wrote:
But given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

Ah. Forgot we had a pro here. ;-)

--
*My dog can lick anyone

Dave Plowman London SW
To e-mail, change noise into sound.

On 26/07/2011 18:26, Bob Eager wrote:
Bedded in on some imperial 7/.029 T&E then:-)

It was actually some heavy duty rubber insulated flex feeding lighting
battens on a stage. I was hanging on to the (earthed) stage framework
with the other hand/arm, 30 feet up, at the time.


RCDs are for wimps....

On Jul 26, 4:00*pm, "ARWadsworth"
wrote:
Dave Plowman (News) wrote:









In article
,
* Neil Williams wrote:
A basic electrical question for you all.

This hasn't been a particular issue so far, because where it did
happen I played it safe and re-stripped the ends. *But mainly to save
effort in future (particularly where there isn't much spare left to
re- strip), I'd like to be sure.

1. If, when stripping the inner insulation off twin and earth, you
"nick" the core with the strippers slightly, is that likely to cause
enough difference to the resistance of that core to make it unsafe?

It would depend on the size of the 'nick'. A mere scratch could be
ignored - something that reduces the diameter appreciably best not.
But given there are lots of devices around for stripping cable
properly, it shouldn't be a question which needs asking.

Like a pair of snips that have cut through a live cable?

--
Adam

Have had several pairs of those, and was oh so glad when a
professional I employed at one time did the same !

Back on topic - I was always taught to nick the end of the cable and
use a pair of pliers to pull out the earth line to strip the outer
sheath back. And then I just pull off the required length of the
inner insulation with the wire cutters.

Rob

robgraham wrote:
Back on topic - I was always taught to nick the end of the cable and
use a pair of pliers to pull out the earth line to strip the outer
sheath back. *And then I just pull off the required length of the
inner insulation with the wire cutters.

I can't quite picture what you're describing there without
picturing the cable being damaged. Maybe time for a Wiki entry?

JGH

On Jul 27, 2:38*pm, jgharston wrote:
robgraham wrote:
Back on topic - I was always taught to nick the end of the cable and
use a pair of pliers to pull out the earth line to strip the outer
sheath back. *And then I just pull off the required length of the
inner insulation with the wire cutters.

I can't quite picture what you're describing there without
picturing the cable being damaged. Maybe time for a Wiki entry?

JGH

OK - in words of one syllable !!

It's inadvisable to cut the outer sheath with a knife where you want
it stripped back to because of the danger of nicking the inner cable
insulation - agreed ?

To avoid this, extract the earth lead from the cut end of the cable by
making a small nick in the face of the cut end with the wire cutters.
Pull the earth wire back to the required length of exposed cable with
pliers such that the earth wire cuts the outer sheath. The outer
sheath can then be cut off using the wire cutters.

Judicious use of the wire cutters can then strip off the required
length of the plastic insulation from the inner cables.

It's always a bit difficult to describe in words what is so easy to
show as a demo, so I hope I've got the idea across.

Rob

robgraham wrote:

It's inadvisable to cut the outer sheath with a knife where you want
it stripped back to because of the danger of nicking the inner cable
insulation - agreed ?

To avoid this, extract the earth lead from the cut end of the cable by
making a small nick in the face of the cut end with the wire cutters.
Pull the earth wire back to the required length of exposed cable with
pliers such that the earth wire cuts the outer sheath. The outer
sheath can then be cut off using the wire cutters.

That bit is clear and I suspect most people use that method

Judicious use of the wire cutters can then strip off the required
length of the plastic insulation from the inner cables.

I think that's the bit that JGH was worried about, using cutters rather
than properly adjusted wire strippers to strip the inner insulation, you
can nick the conductor unless you're careful ... but then of course,
we're all careful, all the time!

On 27/07/2011 21:05, Andy Burns wrote:
robgraham wrote:

It's inadvisable to cut the outer sheath with a knife where you want
it stripped back to because of the danger of nicking the inner cable
insulation - agreed ?

To avoid this, extract the earth lead from the cut end of the cable by
making a small nick in the face of the cut end with the wire cutters.
Pull the earth wire back to the required length of exposed cable with
pliers such that the earth wire cuts the outer sheath. The outer
sheath can then be cut off using the wire cutters.

That bit is clear and I suspect most people use that method

I've used that method, but I've also used another - using a Stanley
knife to cut into the end, with just a slight sideways angle so that it
slides smoothly down the side of the Earth core without nicking it or
the insulation of the phase conductor next to it. It's much easier that
way to strip right back into an accessory box.

SteveW

Andy Burns wrote:
robgraham wrote:

It's inadvisable to cut the outer sheath with a knife where you want
it stripped back to because of the danger of nicking the inner cable
insulation - agreed ?

To avoid this, extract the earth lead from the cut end of the cable
by making a small nick in the face of the cut end with the wire
cutters. Pull the earth wire back to the required length of exposed
cable with pliers such that the earth wire cuts the outer sheath.
The outer sheath can then be cut off using the wire cutters.

That bit is clear and I suspect most people use that method

Judicious use of the wire cutters can then strip off the required
length of the plastic insulation from the inner cables.

I think that's the bit that JGH was worried about, using cutters
rather than properly adjusted wire strippers to strip the inner
insulation, you can nick the conductor unless you're careful ... but
then of course, we're all careful, all the time!

--
Adam

Andy Burns wrote:
robgraham wrote:

I think that's the bit that JGH was worried about, using cutters
rather than properly adjusted wire strippers to strip the inner
insulation, you can nick the conductor unless you're careful ... but
then of course, we're all careful, all the time!

You get so used to it that the inner insulation comes off easily without
damaging the conductor.

Once you get used to a pair of snips you get used to their balance and
cutting forces.

I was more upset when I had to say goodbye to my last pair of Knippex side
cutters than I was the day my wife left me.
--
Adam

"ARWadsworth" wrote in message
...
Andy Burns wrote:
robgraham wrote:

I think that's the bit that JGH was worried about, using cutters
rather than properly adjusted wire strippers to strip the inner
insulation, you can nick the conductor unless you're careful ... but
then of course, we're all careful, all the time!

You get so used to it that the inner insulation comes off easily without
damaging the conductor.

Once you get used to a pair of snips you get used to their balance and
cutting forces.

I was more upset when I had to say goodbye to my last pair of Knippex side
cutters than I was the day my wife left me.

I know how you feel. I would hate to be parted with my 40 year old Lindstrom
side cutters.

Mike

In article ,
ARWadsworth wrote:
I think that's the bit that JGH was worried about, using cutters
rather than properly adjusted wire strippers to strip the inner
insulation, you can nick the conductor unless you're careful ... but
then of course, we're all careful, all the time!

You get so used to it that the inner insulation comes off easily without
damaging the conductor.

Once you get used to a pair of snips you get used to their balance and
cutting forces.

Other thing is to use the side cutters so the flat face of the jaws is
towards the cable end. They are less likely to 'dig in' then.

I was more upset when I had to say goodbye to my last pair of Knippex
side cutters than I was the day my wife left me.

Yes - to use this method you have to have the 'feel' of the cutters.

However, for the inexperience, strippers of the type that are sized for
each cable size, so they only cut into the insulation, are probably the
safest. Snag is decent easy to use ones ain't cheap. Cheap ones do the job
but are harder work.

--
*Elephants are the only mammals that can't jump *

Dave Plowman London SW
To e-mail, change noise into sound.