Unidentified Potentially Live Cable.

[arunciblespoon]

Hi.

I work in a factory. During the course of the days activities towards the end of the day (other competent people left the building) a cable was found by an unskilled person. 

This cable was threaded through a metal work desk that has a functioning florescent tube mounted to it.

It was in trying to find the switch for this light that the cable was found. 

I checked the end of the cable, it had clearly been cut with snips and thrown over the top of this work station. As previously said the cable went into the box section frame of the metal work station. Where the other end was not obvious (in fact it took a long time to find it after the event) and there was a bundle of cables near by going hither and thither. The cable was ordinary three core flex, 1mm maybe 1.5mm at a guess. It had been there some time. 

However now this potentially live cable is dangling in mid air with ordinary people in the area.

My tools, (not with me, at the other end of the factory) comprise

A multimeter ( I would not have wanted to be probing the end of this cable with the meter)

Insulated screwdrivers various sizes.

cutters, insulated.

long nose and short nose pliers, not insulated.

spanners 

wire strippers, uninsulated.

My question is, given the tools available, and the situation described....

What would you do?

 

[Andy™]

get your manager to call someone competent. dont forget EAWR etc...

 

[arunciblespoon]

sorry, I should have said.I am the competant person. Its the p.o.v of other competent people. I am after.

 

[Andy™]

so you, as a 'competent person', have knowingly left a potentially live wire hanging there where someone could get a shock? sorry, but that is not something anyone 'competent' would do. and if you were competent, you would not need to ask. something dodgy going on here...

 

[arunciblespoon]

No I did not leave it hanging there.

Therein lies the problem. In the absence of the correct tools to identify which of all the surrounding boards it came from I took the (perhaps wrong) decision of forcing the end of this cable into earthed metal work to 'kill the cable', find the MCB and lock it off. The breaker was in a board some distance from this cut cable and rather counter intuitive to find. I accept this has its implications, but, given the tools I have described what should I have done. Please don't be so nasty. I am looking for advice on what to do in future, and potentially tell my employers which tools and equipment they should be buying..

 

[NozSpark]

What would I do...

1 verify that the cable is in fact live

2 either... Isolate and remove the cable

or... Make the end safe

If I had to leave the area then I'd firstly isolate the supply

How do you know for certain that the metal work was earthed....

This is not an accepted test method

 

[arunciblespoon]

Thanks nozspark, but this is the problem, I had no idea where to isolate. How to make the end safe? Remember its as it was live.

 

[ProDave]

So where does the cable come from? Out of thin air?

It must emerge from somewhere, some wall plate or junction box or something. Follow it to the source and disconnect it.

 

[arunciblespoon]

The cable came out behind a load of production paper work dissapeared into a nest of others that went left and right and up into the roof space. This point was well out of sight of the cable end dangling.

Eventually it went into what appears to be a south African socket on a 13a plug plugged into a socket.

Should I have left the cable live whilst I went to forage away from it?

 

[Blue Duck]

No connector blocks or tape to hand? Even a volt stick could have come in handy allthough a test lamp would be better.

 

[arunciblespoon]

Connector blocks are fine when you have stripped outer sheath. I figured stripping this off was potentially a greater threat to my situation than what I did. Ordinarily I would have put another engineer on guard whilst the other end was foraged out. To be honest I am astounded at finding what I did. My normal role is fixing machine breakdowns not finding cables cut and laying about.

Sadly no voltstick. This would just have confirmed the cable as live...

I have read that I should have used a signal gen and a detector. This is kit we as a factory don't have.

With the correct tackle hopefully this will never happen again. But in the absence of it what should I have done. I don't like to think I am a cowboy but I just don't know now.

 

[zimmy]

Use a non contact voltage indicator. (Not a 'recognised bit of kit I know but in this case the safer option rather than trying to use probes.) 

Use barriers to make the area around the suspect cable safe.  

Post warning signs to identify the problem. 

Then go hunting. Never, ever,  'short out' a line conductor to earth this is a good way to:  Start fires, blow your face away, electrocute someone.. this list is not exhaustive!!!   If the metal work was not earthed you could have killed someone who may have been in contact with the metal work and earth!  .  Are you mad?

I have to question why you think you are the competent person.  I think you are in need of some serious training along with the people who deem you competent.

Employ someone who has the skills to sort the mess out before someone gets killed.

 

[Blue Duck]

So it was just cut off? No inner sheath exposed? Tape should have done it while you go off and try trace the source maybe a a little sign saying warning live?

As for the cable locator. ..

Can you connect them things to live cables?

Don't think your problem was competence more confidence.



Edit @ zimmy volt sticks aren't reliable they pick up transient voltages from surrounding cables. hours can be wasted tracing a live cable that is actually dead.

 

[arunciblespoon]

Somewhere else someone said use heatshrink. I fear I have committed a rather serious blunder.

As to the signal gen the HSE guide I have got says if cable cores are not accessible cable detection equipment may be used in conjunction with a signal gen.

I have made out a dangerous occurance form at work over the live cable but now face being disciplined over my remedy. Which it looks like is justified. I hope I don't lose my job.

I am normally a stickler for safety but this has me tied up in knots.

 

[Andy™]

so, was this 'potentially live cable' actually live or not? i would blame the idiot who left it, not the person who made it safe, even if that did involve leaving in unattended whilst investigating it... however putting it into a metallic enclosure with the hope of tripping something, without even knowing if said metallic enclosure was earthed in the first place, is definately a big no-no

 

[NozSpark]

Did I read correctly that this end of cable was fed via a "widow maker" (lead with a plug on each end)?????

 

[Blue Duck]

One of these may come in handy in the future although I'm not sure they do one that fits 1.5 mm flex

http://www.ebay.co.uk/itm/like/171337990530?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&device=m&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0

 

[kerching]

Almost all of the cable tracer sets/signal,generator-detectors I have seen require connection to the core.

If the cable "was live" then accessing same could be a bit of an issue

Most cable detectors work on dead cables...except the socket and see Fuse Finder BUT you have to access the cable cores

I have an induction /direct connect genny and cable tracer. I also have a TDR both of which can be used on LIVE and DEAD cables...these can save you being blown out through your wedding ring AND your relatives having half an hour out with the Vicar.

This kit is not the usual,run of the mill gear that your average Spark or Maintenance Electrician would carry

 

[arunciblespoon]

No noz one end was fitted with this south African plug via an adapter into a 13 a socket. The cut end once fed a light fitting that has been replaced with a completely different one.

Andy. I accept that my remedy was wrong. Zimmys post made me realise just how daft I was. I suppose if they sack me its deserved.

Thanks for your insights.

 

[kerching]

One of these may come in handy in the future although I'm not sure they do one that fits 1.5 mm flex

http://www.ebay.co.uk/itm/like/171337990530?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&device=m&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0

Or a WAGO box?