How do you deal with old, dead cables?

[Jupiter01]

Whilst laying some new cables for my brother in laws kitchen, I noticed that there were lots of old cables in the ceiling void. Some were already cut and hanging midair and others were known to be dead as they were no longer being used. I checked for power and also don’t see any corresponding cables/breakers in the Consumer Unit.

I suppose it’s possible that they are energised through some random switch. Unlikely in this situation. It wasn’t possible to trace them to their source as they disappear into other parts of the house.

Q. How do you handle/terminate such cables? Is there a particular convention for handling these?

Thanks in advance

 

[studentspark]

Always presume live, or can become live. The only way to know for sure is trace them to a junction box. Only strip out cables when you can find both ends. Something that disappears into a wall or void, terminate as if it was live. I've found live lead covered cable in a house that was 'rewired' recently.

 

[Jupiter01]

Always presume live, or can become live. The only way to know for sure is trace them to a junction box. Only strip out cables when you can find both ends. Something that disappears into a wall or void, terminate as if it was live. I've found live lead covered cable in a house that was 'rewired' recently.

So put into a wago and box before putting the ceiling on?

 

[studentspark]

If i have a cable that I am unsure of, say just cut and hanging there. I isolate, and terminate the conductors in a connector block, to enable testing.
If I am happy that that cable is not connected to any source of power. I strip out if possible , or terminate it, as if it was live.
Even if you know it is no longer connected. Someone else might find it at a later date and be concerned about it. Thats why I never leave cut cables.

 

[sparkwright]

If you they are dead, and never to be used again, cut them off tight as possible and forget them.

If you know they are dead, but think they may serve some future use such as a future draw wire, cut them off leaving two inches spare.

If you know they are dead, never to be used again, but think there is some 1% chance is may just be used again or made live, cut it off leaving two inches, wrap tape round the end and forget it.

 

[FrodoOne]

If you they are dead, and never to be used again, cut them off tight as possible and forget them.

If you know they are dead, but think they may serve some future use such as a future draw wire, cut them off leaving two inches spare.

If you know they are dead, never to be used again, but think there is some 1% chance is may just be used again or made live, cut it off leaving two inches, wrap tape round the end and forget it.

Really !!!

"If you [know that] they are dead, and never to be used again" - HOW do you "know" that?
In any case, they should be marked as "NO LONGER IN SERVICE" - or similar - at both ends (and NOT cut off short.)

"Short-circuiting" the Line and Neutral conductors (at both ends) may (or may not) be a "good idea", since, if the other end of the conductors is later connected to a "supply", the then the "operating" circuit breaker will give a good indication that "something is wrong".

"If you know they are dead, but think they may serve some future use such as a future draw wire, cut them off leaving two inches spare"
Leave EVERYTHING available as "spare" and mark them as "NO LONGER IN SERVICE" - or similar - at BOTH ends.

Indicating (somehow) where the "other end" is would be a very good idea, in all such cases.

 

[sparkwright]

Really !!!

"If you [know that] they are dead, and never to be used again" - HOW do you "know" that?
In any case, they should be marked as "NO LONGER IN SERVICE" - or similar - at both ends (and NOT cut off short.)

"Short-circuiting" the Line and Neutral conductors (at both ends) may (or may not) be a "good idea", since, if the other end of the conductors is later connected to a "supply", the then the "operating" circuit breaker will give a good indication that "something is wrong".

"If you know they are dead, but think they may serve some future use such as a future draw wire, cut them off leaving two inches spare"
Leave EVERYTHING available as "spare" and mark them as "NO LONGER IN SERVICE" - or similar - at BOTH ends.

Indicating (somehow) where the "other end" is would be a very good idea, in all such cases.

Here we go.

If you are rewiring a property, you usually KNOW what is dead, never to be used again.

If there's some doubt about any old cable, you can simply test it, to give some indication at least, and then decide what you should do with it.

I can't give a rule for every single cable found in an old house, can I? But as usual, common sense should come into it, and if there is any doubt obviously safer measures must be approached.

 

[FrodoOne]

Here we go.

If you are rewiring a property, you usually KNOW what is dead, never to be used again.

If there's some doubt about any old cable, you can simply test it, to give some indication at least, and then decide what you should do with it.

I can't give a rule for every single cable found in an old house, can I? But as usual, common sense should come into it, and if there is any doubt obviously safer measures must be approached.

Sorry.
I did not mean "How do you know they are dead."
What I meant was "How do you know that they will never be used again." - so, to "cut them off tight as possible and forget them." may not be a good idea !

 

[sparkwright]

It MAY not be a good idea, no. No set rules here, and all this 'may not be a good idea stuff' is something the installer will judge when he's working.

Basically I'm talking about just a general rewire, if they are old and not to be used, I can most definitely assume they will not be re-used ever again - because I'm putting nice new ones in. I'm not going to make provision for all the old and sometimes perished cables to be re-used at some point. Especially if they have some old junction box hidden away somewhere. Most definitely not.

Generally, you want all the old redundant stuff removed where possible, to make a nice tidy space under the floor.

But now and again, there may be something like a large redundant cable that's not to be used, but looks in good nick, so I may decide to leave it under the floor, perhaps with a bit of tape on the ends, just in case it may 'save the day' in the future. Just for my own satisfaction.

Obviously they virtually never do get used, and they forgotten too, but it's a quirk of mine.

It's never a good idea to re-use old cables anyway, you don't know enough about them on the bits you can't see.