Identifying live cables

[markthebuilder]

hi gents . I’m currently surveying a property prior to remodelling it... it was a department store and it’s been redeveloped at least once but no one has pulled out the old wiring,
I want to mark up any of the major 415 3 phase that is defiantly live ina simple way so we can focus on tracking and verifying potentially dead cable most of the stuff I’m talking about is between 1.5 inc and 3 inc sea. Will a volt pen do the trick or do I need something different. Obviously anything that seams dead needs tracing and proving before we do any work . I just want to be able to quickly show what’s live so we can protect them and get them shown ondrawings

 

[derek]

I think you need an electrician, a volt pen is no good especially if you are talking about ripping stuff out ready for a refurbishment.

 

[Charlie_]

Do you own a ‘volt pen’ ?
If so, isolate a circuit and then see if you can identify it amongst a bunch of live cables..

 

[TJ Anderson]

Try a "volt pen" on SWA, MICC or FP.......

 

[markthebuilder]

1) I will need a team of sparks befor I’m finishe 2) no I don’t, I have always proved cables at one end or the other or been able to isolate the whole supply. This building is prity vast so when I am sticking my head in places I don’t rally want to go back to and I see a big black cables 2 inch thick I would like a quick way of determining if it’s deep live then I can mark it on the plans. If a volt pen will do volt pen will do it then that will do.. any cables I don’t get a positive result for can get marked up as require further investigation.
However if there is something a bit more reliable than a volt pen I will get one,

 

[ipf]

1) If a volt pen will do volt pen will do it then that will do.. any cables I don’t get a positive result for can get marked up as require further investigation.
However if there is something a bit more reliable than a volt pen I will get one,

In your case the thing more reliable is someone qualified to test correctly and inform you.
It could be very dangerous going about things in the way you intend.

 

[TJ Anderson]

Volt pens are good as an indicator, but won't work through the sheath of many cables.

What cables is it? You mention 2" thick......SWA I'd imagine, a non contact volt stick won't pick that up.

 

[ipf]

Volt pens are good as an indicator, but won't work through the sheath of many cables.

What cables is it? You mention 2" thick......SWA I'd imagine, a non contact volt stick won't pick that up.

We're talking 400v, here TJ. 'Prity vast' sounds like it could be quite complicated to me ( a bleedin' department store), could be cables all over the place. What about sub boards, removing live fuses, etc. God knows what could be live and what might happen with attempted removal.

 

[Deleted member 105166]

Are you intent on keeping any of the old cabling or shall you be renewing all boards and cables? Do you need the existing cabling as a supply during construction works? These factors may influence how you tackle things and in what order. You’ll need to involve an electrician from early on regardless.

 

[derek]

You need an electrician with experience in commercial installs, there can be some really dodgy wiring where there has been countless alterations over the years and it can catch out those who don't carry out a thorough safe isolation procedure.

 

[TJ Anderson]

We're talking 400v, here TJ. 'Prity vast' sounds like it could be quite complicated to me ( a bleedin' department store), could be cables all over the place. What about sub boards, removing live fuses, etc. God knows what could be live and what might happen with attempted removal.

I know......Totally agree!! Shouldn't be relying on a volt stick for it. If he is getting a spark in anyway....why can't they do it....

 

[ipf]

I know......Totally agree!! Shouldn't be relying on a volt stick for it. If he is getting a spark in anyway....why can't they do it....

By the way, might be an old Woolworths ….did they used to sell volt sticks?

 

[Charlie_]

My new fluke t6 1000 arrived yesterday.
I’m going to start putting it through it paces tomorrow so will let you know but then that will only be useful for single cores...
What you are attempting to do is very much involved.. There is specialist equipment available to identify individual swa cables but need to be used by competent operatives..
I have regularly been asked to make building sites safe for demolition/refurbishment works.. my solution - isolate everything and set up temporary supplies..

 

[Andy78]

I want to mark up any of the major 415 3 phase that is defiantly live

If these cables are going to be defiantly live you're gonna need to make doubly sure those stubborn buggers are dead.

If a volt pen will do volt pen will do it then that will do..

No a volt pen will not do. You need someone who knows safe isolation procedure in accordance with HSE guidance and compliance with the EAWR. They need to be using approved equipment and have the knowledge to use it correctly. In short, an electrician.

Any blundering about with limited knowledge and volt pens could put people in serious danger, and those that have put them in danger exposed as incompetent and action taken against them.

 

[markthebuilder]

Thanks ty for the constructive response. TJ the cables are Mostly big .others .are f’ing .. IPF is correct though there are sub boards everywhere and his implication reasonable if incorrect . I came across an installation today that ,looked derelict but on closer inspection still had one apparently live main switch with a supply going somewhere So marked it on the plans as poss live needs further investigation ( I suspect it feeds a lift Moyer 4 stories up) I also found a cable that entered the building 30 m from where i would have expected it to I know that’s live because I can see the meter going round ...that’s going down as arrange dno to relocate meter. However some of these cables I don’t think we can easily trace back to source or termination to prove. So at this stage being Abel-to show a cable is live or possibly deadwill help me plan the works.

 

[Charlie_]

In this game I’m afraid there is no such thing as possibly dead..
Your only assumption can be that all cables are live or can become live..

 

[Pete999]

You Definitely need an electrician to sort this for you Mate, and definitely don't rely on a volt pen, that definitely no no . Definitely a no no, I'm defiantly right about that lol

 

[derek]

Seriously, whoever you are getting to design and install the new work, get them involved now and save yourself a prison sentence if someone gets hurt because you haven't isolated everything correctly.

 

[Bobster]

Cable spiking - https://www.electriciansforums.co.uk/threads/cable-spiking.61644/#post-581836

For proving them dead if your unsure.

 

[Pete999]

Cable spiking - https://www.electriciansforums.co.uk/threads/cable-spiking.61644/#post-581836

For proving them dead if your unsure.

Having seen it done on 11KV I agree.

 

[Bobster]

Having seen it done on 11KV I agree.

Done it plenty on redundant 11/33Kv cables, still thankfully never seen it go through a live one.

Although I have seen the aftermath of someone using it on a live cable in one of the training centers I visited. There wasn't much left, but nobody was hurt.

 

[Pete999]

Agree Mate I was 11KV AP for several years and although you were dead sure you had identified the right cable to spike, it gave me butterflies, until of course you had fired the spiker and nothing went bang, except for the spiker, going off.

 

[Baddegg]

I don’t understand why you’d want responsibility for this mark, as you can’t have the relevant insurance to cover you should the worst happen, in a development of that size the cost of getting a spark in and doing it properly must be a drop in the ocean

 

[littlespark]

A big department store. Surely there are EICRs going back years documenting every circuit, every cable with sizes.... and everything is labelled....

No?

 

[The Ghost]

However if there is something a bit more reliable than a volt pen I will get one,

Yeh it's called an electrician.

 

[telectrix]

Yeh it's called an electrician.

absofruitly.

 

[davesparks]

So at this stage being Abel-to show a cable is live or possibly deadwill help me plan the works.

A volt pen will light up on some dead cables and make them appear live, it won't light up on a lot of live cables and make them appear dead.

So you would end up with a plan showing cables as being live which are actually dead, a bunch of possibly live cables which are actually dead, a lot of possibly live cables which are actually live. And not forgetting all manner of cables which appear dead but actually come live when various timeswitches, back up systems etc etc come on.

So basically you are going to waste a lot of time making yourself feel like you are making a valid contribution and saving money when in reality you'll have no more useful information than when you started.

 

[Spoon]

So basically you are going to waste a lot of time making yourself feel like you are making a valid contribution and saving money when in reality you'll have no more useful information than when you started.

This pretty much sums up the the thread.

 

[markthebuilder]

Well I have to say the thread defiantly highlights the significant concerns the professional electrical community has that every person who asks a straight forward question relating to electrical work is potentially going to bar- b-q themselves. It is commendable but the reaction to the meet mention of a volt pen a little laughable. Seemingly the best tools for what we actually need is a “grumbler”and an “approved person” I have a guy combing from the dno next week and we will come up with a plan to fill the gaps between what’s on the utility drawings and what is as built /amended and left in during previous refurb . Then I can give results to my m&e guys all that said I’m still getting myself a volt pen to make one final check on any cable before I let anyone start cutting with a sthil Which reminds me we need to cut some access holes into ducts that look like cement sheet. Is there a chemical you can put on the sheets that turns green if it’s defo cement or red if its asbestos?

 

[Charlie_]

No competent person in their right mind would use a volt pen to verify a cable for safe isolation..

 

[markthebuilder]

If you read my post Charlie I never sugesred I would,In fact I never mentions isolation . I simply asked if there was a better tool for identifying wether a cable is live. Specifically big ones when your only access is to the model of it and it’s source and end can’t be determined ....

 

[static zap]

Bright idea , a light bulb with a spike ,on a neutral wander lead ,may do it ... but the approved tool will be more pricey ... Do verify its still working every so often !
(Yep you are likely to go BANG if you don't know -nor have a plan)

 

[Charlie_]

Ahh sorry my mistake, when somebody talks about cutting through cables I automatically think ‘safe isolation’..
Apologies for my assumptions..

Ok, from what I’ve heard, try these ‘volt pens’
Megger
Fluke
Kewtech - guy on YouTube uses them so must be really good

Please give us some feedback after your meeting with the dno guy, I’m really interested to hear more about this

 

[Andy78]

I have decided the OP is either on a wind up or as thick as mince and stubborn as mud. Best left to it in both cases.

 

[Tony Reidy]

1) I will need a team of sparks befor I’m finishe 2) no I don’t, I have always proved cables at one end or the other or been able to isolate the whole supply. This building is prity vast so when I am sticking my head in places I don’t rally want to go back to and I see a big black cables 2 inch thick I would like a quick way of determining if it’s deep live then I can mark it on the plans. If a volt pen will do volt pen will do it then that will do.. any cables I don’t get a positive result for can get marked up as require further investigation.
However if there is something a bit more reliable than a volt pen I will get one,

There is its called an electrician

 

[Spoon]

....all that said I’m still getting myself a volt pen to make one final check on any cable before I let anyone start cutting with a sthil

Any electrician will ignore your checks (with the volt pen) and check all cables themselves but go ahead and do your checks, it's only a waste of your time and not theirs.

 

[Andy78]

Just saying .......

£160k fines after demolition worker burned - https://www.theconstructionindex.co.uk/news/view/160k-fines-after-demolition-worker-burned?utm_source=dlvr.it&utm_medium=facebook&fbclid=IwAR2AXzrRGONW3jPwrwAM0dv0j8hOVINsHWbV7ou2gMEvYxe-YCM2FbdNXwA

 

[Charlie_]

Just saying .......

£160k fines after demolition worker burned - https://www.theconstructionindex.co.uk/news/view/160k-fines-after-demolition-worker-burned?utm_source=dlvr.it&utm_medium=facebook&fbclid=IwAR2AXzrRGONW3jPwrwAM0dv0j8hOVINsHWbV7ou2gMEvYxe-YCM2FbdNXwA

Probably because it wasn’t all checked first with a volt pen

 

[Spoon]

Just saying .......

£160k fines after demolition worker burned - https://www.theconstructionindex.co.uk/news/view/160k-fines-after-demolition-worker-burned?utm_source=dlvr.it&utm_medium=facebook&fbclid=IwAR2AXzrRGONW3jPwrwAM0dv0j8hOVINsHWbV7ou2gMEvYxe-YCM2FbdNXwA

I'm sure the OP can afford an 80 grand fine, so hes ok to tell the electrician he's checked the cable with his volt pen and its dead..

 

[Charlie_]

Day 1..
Site foreman turns up and all is ok, the wand has not lit up!
Izzy wizzy lets get busy!

 

[Deleted member 105166]

I have a guy combing from the dno next week and we will come up with a plan to fill the gaps between what’s on the utility drawings and what is as built /amended and left in during previous refurb .

Good luck with that. The DNO are only going to be interested in what's on their side.

all that said I’m still getting myself a volt pen to make one final check on any cable before I let anyone start cutting with a sthil

Your electrician will prove dead using an approved voltage indicator in conjunction with a proving unit and then - and only then - cut redundant cables with the tools he/she deems appropriate - probably SWA ratchet cutters.

Which reminds me we need to cut some access holes into ducts that look like cement sheet. Is there a chemical you can put on the sheets that turns green if it’s defo cement or red if its asbestos?

Another non-DIY job. Commission an asbestos survey from a company competent and insured to survey and certify.

 

[davesparks]

If you read my post Charlie I never sugesred I would,In fact I never mentions isolation . I simply asked if there was a better tool for identifying wether a cable is live. Specifically big ones when your only access is to the model of it and it’s source and end can’t be determined ....

There is no way to determine whether an armoured cable is live or not from the outside of the cable, the armour prevents detection of the magnetic field around the conductors.
A spiking gun as suggested earlier is the only way I am aware of for cables that cannot be reliably traced.

 

[Lucien Nunes]

As usual, there is a lot of noise here about not using a volt-stick to prove dead as part of a safe isolation procedure. This is sound advice but was never part of the OP's intention, as far as he states. He wants to eliminate cables that are presently live and in use, from those requiring further investigation to determine whether they are long since redundant from the previous installation and should have been ripped out at the last rewire.

For my money, a volt-stick can be useful for this process, but as mentioned above, it won't work through the armour of an SWA or the foil of an FP. It detects electric field (not magnetic) and the earthed shield prevents the cable radiating significant electric field. A cable on load will still radiate magnetic field and some types of detector can measure this, but not a regular volt stick, and if there is no load, even if the cable is live there will be no magnetic field.

So, it requires a rather more sophisticated approach to avoid, as Davesparks neatly sums up, ending up with no more useful information on which cables are live than when you started.

I will say again in defence of the voltstick, that if you properly understand its behaviour and know about spatial distribution of electric fields and hence its response pattern, it can be quite reliable and accurate and can reveal things no approved indicator or even multimeter can tell you.

 

[Spoon]

Can I ask you a question @Lucien Nunes . If the OP had the correct tool for the job and tested said cables, would you trust the results or check the wires yourself, before messing with them?

 

[Deleted member 105166]

Can I ask you a question @Lucien Nunes . If the OP had the correct tool for the job and tested said cables, would you trust the results or check the wires yourself, before messing with them?

I think everyone here would do their own check irrespective of what tool someone else may or may not have used. Even when working with a long trusted colleague, you still satisfy yourself, as everyone can make mistakes or misunderstandings.

 

[Lucien Nunes]

Of course, if I wanted to do anything to the cables I'd test them myself first, but from the original explanation, that is not the case in point. He wanted to sort them into two categories:
a) Part of operational installation, probably being retained unless sparks says otherwise so mark on plan and don't invest time tracing at this stage.
b) Probably part of obsolete installation. Get it traced, proven dead and ripped out.

The actual proof that a cable is dead is a later part of the process.

 

[Spoon]

I think everyone here would do their own check irrespective of what tool someone else may or may not have used. Even when working with a long trusted colleague, you still satisfy yourself, as everyone can make mistakes or misunderstandings.

That's what I was getting at mate. The OP is just waiting his time marking up cables.

 

[Pete999]

Can I ask you a question @Lucien Nunes . If the OP had the correct tool for the job and tested said cables, would you trust the results or check the wires yourself, before messing with them?

To answer your question, Spoon, in lieu of Lucien's reply sorry Lucien.
If you are proving some thing is dead then the person in charge of the Demolition should be present at the "Safe Isolation procedure" and be shown that the circuitry IS DEAD and all access points of possible re-energising are securely locked OFF, and the keys are safe with the Authorised person issuing the permit to work.
This permit will become a legal document for the duration of the works covered by this Permit.
As soon as the work is completed the PtoW should be signed Off as work completed and a copy kept on file for reference.
No further work should be carried out on that site with regards to demolishing electrical work, until a new Permit has been issued, if this system is adhered to by the book it should be accident free.

 

[Pete999]

Can I ask you a question @Lucien Nunes . If the OP had the correct tool for the job and tested said cables, would you trust the results or check the wires yourself, before messing with them?

To answer your question, Spoon, in lieu of Lucien's reply sorry Lucien.
If you are proving some thing is dead then the person in charge of the Demolition should be present at the "Safe Isolation procedure" and be shown that the circuitry IS DEAD and all access points of possible re-energising are securely locked OFF, and the keys are safe with the Authorised person issuing the permit to work.
This permit will become a legal document for the duration of the works covered by this Permit.
As soon as the work is completed the PtoW should be signed Off as work completed and a copy kept on file for reference.
No further work should be carried out on that site with regards to demolishing electrical work, until a new Permit has been issued, if this system is adhered to by the book it should be accident free.

 

[Spoon]

To answer your question, Spoon, in lieu of Lucien's reply sorry Lucien.
If you are proving some thing is dead then the person in charge of the Demolition should be present at the "Safe Isolation procedure" and be shown that the circuitry IS DEAD and all access points of possible re-energising are securely locked OFF, and the keys are safe with the Authorised person issuing the permit to work.
This permit will become a legal document for the duration of the works covered by this Permit.
As soon as the work is completed the PtoW should be signed Off as work completed and a copy kept on file for reference.
No further work should be carried out on that site with regards to demolishing electrical work, until a new Permit has been issued, if this system is adhered to by the book it should be accident free.

I'm presuming the 'proving some thing is dead' and 'safe isolation procedure' is carried out by an electrician and not whatever the OP is..