Identifying live cables

[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.