How to verify that apparently-redundant wiring actually is?

[endecotp]

Dear experts,

I have a cupboard that at one time must have contained a hot water cylinder. At some point is was removed as the flat now has a combi boiler.

The cupboard has various apparently-redundant pipes and wires which I would like to remove to increase the available space and make it look tidier. The wiring includes a square metal junction box and three metal conduits; the junction box has a long terminal block strip with complex connections and many yellow or white wires. A quick check found none to be live. My guess is that this is the old wiring for the central heating timer and valves, and probably the immersion heater, and that it is now all redundant.

What would be the correct procedure for establishing that it really is redundant and can safely be removed?

It is difficult to follow the wires and prove that they are not connected to anything because they go into metal conduits, mostly under the floor, which are hard to follow.

Thanks.

 

[ericmark]

I was given the task of removing redundant wiring where a new concrete batching plant had replaced an old one and the electrician who had been there at the time of the replacement had identified the redundant wires to be removed.

However I still did my one tests for dead and having proved the cables feeding a junction box which was missing a lid were are dead I proceeded to remove them.

However it transpired one of the cables feed an augur and it was only live when the PLC controlling the batching plant decided that auger was required so during the removal that cable became live. As luck happened no one was touching the cable when this happened but it was more by good luck than good judgement.

Learn from may error and consider any cable may become live so before removal all power to house must be removed and the cable end must be considered and going to be live on turning the power back on so must be sealed so that no contact can me made.

Be it a thermostat or a timer cables can become live when consider dead so either find the origin or consider as live.

 

[endecotp]

Right, it's easy enough to turn off all the power before starting work. But it would then be sensible to terminate the cut cables in some "safe" fashion, wouldn't it?

 

[viewer]

Are there any clues at the CU end - redundant breakers, wires disconnected and made safe or live attached to the earth bar? There may be old markings which show the history.

 

[PrenticeBoyofDerry]

What would be the correct procedure for establishing that it really is redundant and can safely be removed?

You would need to investigate the route of the cable, some continuity testing and of course testing for voltage would be required (Use a two probed voltage tester)

It is difficult to follow the wires and prove that they are not connected to anything because they go into metal conduits, mostly under the floor, which are hard to follow.

Things are never straight forward but if you want to remove the cable, the cable ends will need to be identified and proved safe so you can remove, also investigate for cables within the conduit that are still functional and live, as you don't want to be damaging and removing them, when removing the redundant heating circuit.

 

[endecotp]

Yes there is a 15A mcb in the cu that seems to do nothing and which I had guessed might be for an old immersion. When I turn it on, nothing in this junction box actually becomes live but a multimeter shows up to about 20V ac to earth on many of the wires; due presumably to coupling from adjacent conductors in the conduit. Hmmmmm.

 

[viewer]

ALL Power off. Join Live and Neutral wires which went to the unused 15 (16?) A MCB and check for continuity with multimeter at IH end.