Identifying live cables

[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..

 

[Pete999]

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..

By someone who has been made responsible for that particular installation, and has been appointed as the Authorised person for said installation, He/She will/ should be familiar with that installation, and hold the relevant qualifications and APs ticket, like I said before Spoon there are/ have been far to many accidents/injuries caused by lack of disciplined procedures in this area, might seem ---- to the Layman, trust me I have been on the end of an investigation by the HSE for precisely this sort of scenario, and it's not something I would wish on my worst enemy, very traumatic for all parties, I was prove the innocent party, but my AP ticket was suspended for 6 months.

 

[markthebuilder]

Thank you Lycian for your clear articulation of my posts, to all I apologise if I had drunk to much wine to articulate my point correctly . For clarity if certain cables on the job are identified as live then they will dramatically alter the proposed sequence of work and mean closing a number of businesses sooner rather than later. If on the other hand they appear to be dead then it will be worth proceeding with further investigation to prove or otherwise that status and if proved dead proceed with some sub ground level demolition building works and asbestos removal .without inconvenience to those livening and working above.
To those whose simple response was get an electrician to tell you , I am still intrigued to know what magical powers electricians are imbued with that enables them to state wether the cable they are looking at is live or not when they don’t know where either end goes and so are left with what they can see.
When we get into the job a bit more I will post an update and some picks. I will also post any work packages that arise as they are formed up.

 

[The Ghost]

I am still intrigued to know what magical powers electricians are imbued with that enables them to state wether the cable they are looking at is live or not

No magic involved, it is training, proper equipment, competency, knowledge of systems and experience. However you seem to resist the idea of doing something that would be legally required of you and should be common sense.
You are not competent to undertake this kind of testing and would be working outside of EAWR, H&S act, as well as BS7671. However you came here for advice and the advice to get an electrician may save your life or others life or injury to you or others. Personally I am aghast at your cavalier attitude to safety, shown by the above reply. You say you are being barbecued because you asked, you rightly deserve flaming with such an obdurate resistance to what is sound and wise advice. But hey what do we know, I wonder why you bothered asking if you don't like the simple advice to get someone qualified and legal to do such work. What would it cost? Is it the money stopping you or just stubbornness. I am concerned genuinely at your approach!

 

[Deleted member 105166]

To those whose simple response was get an electrician to tell you , I am still intrigued to know what magical powers electricians are imbued with that enables them to state wether the cable they are looking at is live or not when they don’t know where either end goes and so are left with what they can see.

No magical powers, just the knowledge, experience and equipment to do so accurately and safely, with the appropriate liability insurance cover.

At the beginning of the topic, you said...

I’m currently surveying a property prior to remodelling it

...so what exactly is your role - not being nosey, just this may help people understand things a little better. Are you the owner/developer/main contractor/QS/other role?

 

[Spoon]

To those whose simple response was get an electrician to tell you , I am still intrigued to know what magical powers electricians are imbued with that enables them to state wether the cable they are looking at is live or not when they don’t know where either end goes and so are left with what they can see.

I'll try and answer this for you. People who have a lot more experience then in this can correct me if I'm wrong.

Bugger..... @Vortigern beat me to it...

 

[Pete999]

No magical powers, just the knowledge, experience and equipment to do so accurately and safely, with the appropriate liability insurance cover.

At the beginning of the topic, you said...

...so what exactly is your role - not being nosey, just this may help people understand things a little better. Are you the owner/developer/main contractor/QS/other role?

Seems like as with most Builders, the end product is devoid of any common sense, b---er safety just get it done regardless.

 

[Norah Nabino]

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 ....

The fact is you have to perform an isolation procedure to properly identify dead or live cables.
To do that you cannot use a volt stick.

 

[Pete999]

The fact is you have to perform an isolation procedure to properly identify dead or live cables.
To do that you cannot use a volt stick.

A profound statement Norah. one most Electricians should be aware of.

 

[Norah Nabino]

No magic involved, it is training, proper equipment, competency, knowledge of systems and experience. However you seem to resist the idea of doing something that would be legally required of you and should be common sense.
You are not competent to undert 8ake this kind of testing and would be working outside of EAWR, H&S act, as well as BS7671. However you came here for advice and the advice to get an electrician may save your life or others life or injury to you or others. Personally I am aghast at your cavalier attitude to safety, shown by the above reply. You say you are being barbecued because you asked, you rightly deserve flaming with such an obdurate resistance to what is sound and wise advice. But hey what do we know, I wonder why you bothered asking if you don't like the simple advice to get someone qualified and legal to do such work. What would it cost? Is it the money stopping you or just stubbornness. I am concerned genuinely at your approach!

Simple answer is he is totally incompetent
He does not know what to do ,how to do it and what equipment and procedure to use.

 

[naylorpd]

As an amateur DIYer I bought a volt stick once, all of a tenner from Screwfix or suchlike. Tried it on a cable I knew was live, not even buried. It didn't light up. Decided I did not want to risk my life for a tenner. Took back for a refund.