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Topic Title: Safety knife for cable
Topic Summary:
Created On: 18 September 2017 12:44 PM
Status: Read Only
Linear : Threading : Single : Branch
 Safety knife for cable   - markdiazlop - 18 September 2017 12:44 PM  
 Safety knife for cable   - broadgage - 18 September 2017 04:45 PM  
 Safety knife for cable   - markdiazlop - 18 September 2017 08:05 PM  
 Safety knife for cable   - dustydazzler - 18 September 2017 08:16 PM  
 Safety knife for cable   - broadgage - 18 September 2017 10:20 PM  
 Safety knife for cable   - dustydazzler - 19 September 2017 05:51 AM  
 Safety knife for cable   - mapj1 - 18 September 2017 11:04 PM  
 Safety knife for cable   - Jaymack - 20 September 2017 12:08 PM  
 Safety knife for cable   - rogerbryant - 20 September 2017 12:55 PM  
 Safety knife for cable   - Jaymack - 20 September 2017 01:24 PM  
 Safety knife for cable   - ToniSM - 19 September 2017 12:32 AM  
 Safety knife for cable   - jonny705 - 19 September 2017 12:40 PM  
 Safety knife for cable   - markdiazlop - 20 September 2017 11:29 AM  
 Safety knife for cable   - alancapon - 20 September 2017 05:06 PM  
 Safety knife for cable   - broadgage - 20 September 2017 08:31 PM  
 Safety knife for cable   - rocknroll - 20 September 2017 10:58 PM  
 Safety knife for cable   - mapj1 - 20 September 2017 11:35 PM  
 Safety knife for cable   - Nedryerson - 25 September 2017 04:39 PM  
 Safety knife for cable   - mapj1 - 25 September 2017 08:49 PM  
 Safety knife for cable   - Fm - 26 September 2017 07:39 AM  
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 18 September 2017 12:44 PM
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markdiazlop

Posts: 7
Joined: 13 September 2017

Hello!!
Can anyone recommend a good safety knife for cable cutting? Non-conductive ceramic blade could be really useful. I did a quick research and found the Link Removed and some Link Removed by Slice. Any information about them? More options? Any recommendations on blade shape?

thanks!!!

Edited: 02 October 2017 at 11:24 AM by markdiazlop
 18 September 2017 04:45 PM
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broadgage

Posts: 2387
Joined: 07 August 2007

What type of work are you contemplating ?

For cutting allegedly dead cables in order to remove them, I would test to prove dead and then "just in case" would use insulated cutters held in a gloved hand for small cables. Dependant on the degree of risk, other PPE may be prudent.
For large cables, specialist tools that "spike" or cut the cable remotely are available. Once thus proved dead, the remainder may be cut with bolt cutters or an angle grinder.

If on the other hand, jointing or similar work on live cables is being considered, then as well as proper training and PPE, I would expect that the employer would provide tools for this work.
Knives used by cable jointers normally have a standard steel blade and a moulded insulating handle. Both hooked and straight blades have their merits and I would expect both in a jointers tool kit.
 18 September 2017 08:05 PM
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markdiazlop

Posts: 7
Joined: 13 September 2017

Thanks! the knife is for general cutting, wire stripping... and that kind of things. I am looking for a everyday carry. For large cables I am more into bolt cutters, as you suggested.
 18 September 2017 08:16 PM
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dustydazzler

Posts: 1353
Joined: 19 January 2016

I don't know many sparks who cut and strip cables using a utility knife (barring striping back the outer sheath or SWA)
I defo wouldn't be cutting live through cables with any knife even if it had a rubberised handle.
I don't think I have ever come across a knife with a ceramic blade but I'm sure that they must exist somewhere
 18 September 2017 10:20 PM
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broadgage

Posts: 2387
Joined: 07 August 2007

Knives with a ceramic blade certainly exist and are sold for kitchen purposes.

As regards a knife for stripping cables, I think that this may be a USA thing ?
The American armed forces certainly used to teach that wires should be stripped with a knife. "By a whittling process, rather similar to the sharpening of a pencil. And NEVER with the knife blade or other cutting tool at right angles to the wire"
It was considered that cutting the insulation at right angles carried too much risk of nicking the conductor and consequent risk of breakage.

In the UK I have read a recommendation that small aluminium conductors should be striped as above, on account of being relatively fragile.

A great many American civilian electricians, or instructors, learnt their trade in the armed forces.
Other organisations may have taken the view that the military way was the right way.

I would only use a knife to strip larger conductors, say 10mm and up.
 19 September 2017 05:51 AM
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dustydazzler

Posts: 1353
Joined: 19 January 2016

Originally posted by: broadgage

Knives with a ceramic blade certainly exist and are sold for kitchen purposes.



As regards a knife for stripping cables, I think that this may be a USA thing ?

The American armed forces certainly used to teach that wires should be stripped with a knife. "By a whittling process, rather similar to the sharpening of a pencil. And NEVER with the knife blade or other cutting tool at right angles to the wire"

It was considered that cutting the insulation at right angles carried too much risk of nicking the conductor and consequent risk of breakage.



In the UK I have read a recommendation that small aluminium conductors should be striped as above, on account of being relatively fragile.



A great many American civilian electricians, or instructors, learnt their trade in the armed forces.

Other organisations may have taken the view that the military way was the right way.



I would only use a knife to strip larger conductors, say 10mm and up.


In America and Canada their preference is to totally strip back the cables prior to inserting in the reception box.
They then simply coil the cores up ready for 2nd fix once the dry walling and painting is complete.
I have seem their electricians lay the cable flat of the floor and spilt the cable straight down the middle using a knife then just slice off the outer sheath. They rarely use side cutters like we do. They do use big loppers (eagles beak) for cutting heavy gauge wire thou.
 18 September 2017 11:04 PM
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mapj1

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Joined: 22 July 2004

It may be an age thing, for those at the opposite end of the scale to the 21st century unzipping of twin and earth by using the CPC as a tin opener.
Older cloth covered VIR and so forth would be gently circumcised to cut the strands of the cloth jacket but not deep into the rubber, so not scratching the tinned copper.
Usually the old sweats used the sort of pocket knife that nowadays lands you in trouble if you forget it is in your pocket and take it down the road with no good reason, and you can't take to jobs in certain schools and similar places
There are a variety of lovely tools for stripping that don't have exposed blades, but almost any building knife will remove modern insulation.
For taking stuff out, assuming its not so big its hacksaw time, I'd reach for a tool I affectionately call my 'chompers'


-------------------------
regards Mike
 20 September 2017 12:08 PM
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Jaymack

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Originally posted by: mapj1
Older cloth covered VIR and so forth would be gently circumcised to cut the strands of the cloth jacket but not deep into the rubber, so not scratching the tinned copper.


The outer sheath of the VRI was cut, probably using a sharpened, insulated hacksaw blade, (as in my case). It had to be cut back about 12mm at terminations leaving the exposed rubber, since the sheath was considered to be hyroscopic. Not many people know that!

Regards
 20 September 2017 12:55 PM
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rogerbryant

Posts: 979
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I note the VRI comment. In this case VIR was correct as the insulation material was Vulcanised India Rubber. For a complete cable VRI, Vulcanised Rubber Insulated can be used. Vulcanised Bitumen Insulation also existed.

Reference Pirelli General Cable Book, First edition 1925

Best regards

Roger
 20 September 2017 01:24 PM
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Jaymack

Posts: 5357
Joined: 07 April 2004

Originally posted by: rogerbryant
I note the VRI comment. In this case VIR was correct as the insulation material was Vulcanised India Rubber.


We were taught "Vulcanised Rubber Insulated" but it still doesn't smell sweet. .......... You'll find V.R.I. in part P guidelines.

Reference: 13th Edition.

Regards

Edited: 20 September 2017 at 01:54 PM by Jaymack
 19 September 2017 12:32 AM
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ToniSM

Posts: 329
Joined: 21 November 2006

I wouldn't use anything other than a Stanley knife, blunt blades = slips and cuts.

Only once in forty years have I cut myself making off a cable. Stuck in the back of an MCC panel I asked one of the electricians to pass me one of my Stanley knifes, he passed me his own, he may as well have passed me an axe.

-------------------------
Could there be a better way?

In theory yes, but in practice?
 19 September 2017 12:40 PM
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jonny705

Posts: 153
Joined: 26 September 2015

I remember an older sparky saying he always cut the t/e with a knife and never used the cpc to yank through it, he wasn't taught that way.

I know the BT guys use a little stripping knife a lot, as one gave me his old one, it's got a small curved blade on it .

I have some Weicon self strippers , work great on the flex cables as really quick and they are designed for it , but they were expensive.

Those really cheap ones I like that are two opposed 'V's as you can strip most domestic cables including alarm and bt solid cable by feel really well.

I have bought some Knipex '6 in 1' plier looking things , they have the pre cut holes for 1.5/2.5 mm which are accurate, long nose pliers to bend the cables over, and handy for poking wires in /out of a busy board, and a larger circular cutter that will accommodate 25 mm tails, they are probably the best idea I have seen for a while.
 20 September 2017 11:29 AM
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markdiazlop

Posts: 7
Joined: 13 September 2017

Thank you so much for all your replies!! So much information here!!
I asked about safety knives with ceramic blades because blades are non-sparking, non-conductive... I am more worried about that kind of things. Not worried about cutting myself.

I don't know why the links I posted are not working, but I found some ceramic utility knives that looks like the kind of things I want to carry inside my pocket for everyday duties. Not only sparking things.



I also found some cable knives by a German company and they also seem so interesting but not something for using outside work.



Did you ever use some of them? I am aware that sometimes safety features are not well implemented and tools are safer but not good for working.
 20 September 2017 05:06 PM
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alancapon

Posts: 6882
Joined: 27 December 2005

Originally posted by: markdiazlop
. . . I found some ceramic utility knives that looks like the kind of things I want to carry inside my pocket for everyday duties. . .

Not sure that is wise. It would be an interesting discussion with a police officer why you are carrying a "bladed weapon" made from materials that don't show up in a metal detector. . .

Regards,

Alan.
 20 September 2017 08:31 PM
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broadgage

Posts: 2387
Joined: 07 August 2007

Originally posted by: alancapon

Originally posted by: markdiazlop

. . . I found some ceramic utility knives that looks like the kind of things I want to carry inside my pocket for everyday duties. . .


Not sure that is wise. It would be an interesting discussion with a police officer why you are carrying a "bladed weapon" made from materials that don't show up in a metal detector. . .
Regards,
Alan.


Agree.
I suspect many ceramic bladed knives are purchased specifically because they do not show up on metal detectors, and are therefore useful as weapons.
 20 September 2017 10:58 PM
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rocknroll

Posts: 9541
Joined: 03 October 2005

Legislation requires that a metal strip is bonded into the handle of a ceramic knife at manufacture.

Regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 20 September 2017 11:35 PM
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mapj1

Posts: 9371
Joined: 22 July 2004

Oh for simpler times....
oh and as regards VIR vs VRI and books from 1925, I am
a) not that old
b) not soo worried about the abbreviations so long as we know what we are discussing.

Oh my, sharpened hacksaw blades as home made knives is a throwback.
Sort of thing I still do at home, a its a quick flick on the grinder and they take a quick edge for carving profiles and striking the back with a hammer as a hacker, but I'd never dare carry one at work.
We'll be reminiscing about how many turns of Empire Brand black cloth tape used as a handle on the things next.

-------------------------
regards Mike


Edited: 20 September 2017 at 11:42 PM by mapj1
 25 September 2017 04:39 PM
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Nedryerson

Posts: 90
Joined: 12 December 2009

Talking about old books, I recall whilst crawling around in the loft of my house I came across lengths of wood with two parallel grooves machined therein.

These turned out to be remnants of a wiring system which went under the name of The Wood Casing System. Apparently the timbers were originally fitted with a wood capping to retain the conductors in the grooves and I believe porcelain beads could be used to insulate the conductors as they emerged from the casing.

In my 1907 copy of 'Technical Electricity' it says this under the heading of 'Disadvantages of The Wood Casing System'

1. It is not fireproof; In fact it is highly inflammable
2. It is unsuited for exposed and damp situations, for it readily absorbs moisture and in this condition is really dangerous.
6 ......." the utilization of the casing for hat pegs, picture hangers, and physical developers (? eh) , the best advice that can be given is to quote that of our best friend "Punch" - DON'T

Apart from that - Great stuff !
 25 September 2017 08:49 PM
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mapj1

Posts: 9371
Joined: 22 July 2004

I think they mean folk doing pull-ups from it ,as the more athletic of us sometimes do by curling our fingers over the tops of door frames in a modern house.
My tip is not to do it in anyone else's house unless you are confident of the security of the architrave, or do not value the houseowners friendship. Similar things sometimes happen to steel conduit if it is at a height and spacing from the wall that it affords a good finger curl hand grip.

-------------------------
regards Mike


Edited: 25 September 2017 at 09:15 PM by mapj1
 26 September 2017 07:39 AM
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Fm

Posts: 1713
Joined: 24 August 2011

Personally I always used a Stanley knife, when I worked with BP, they tried all sorts of fancy knives in an it to reduce cuts, none worked and we resorted to fixed Stanley knifes and Kevlar gloves.
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