What type of cable is this?

[dg2908]

I've never come across this sort of cable in a domestic installation before- bizarrely apart from the loft lights the rest of this 1960s house is wired in PVC.
IR tests out fine thankfully.

 

[Gavin John Hyde]

Looks like fabric braided. I think it was hardened with a wax or varnish type compound to further strengthen. If i come across it i tell the customer to consider changing but rarely have i tested it and it come back with a poor IR. It seems to live forever around this way.

 

[davesparks]

That looks like overbraided VIR cable, long overdue for replacement. It is an early equivalent of modern day singles and shouldn't have been installed outside of conduit.

I suspect the main reason you are getting a good IR reading is that there are no Earth wires in close proximity to the cables to give you any reading. There is no point testing the insulation resistance between two points which are insulated by a massive air gap!

There is a tendency these days to trust too much to an IR test and not actually look at the evidence

 

[dmxtothemax]

there was a lot of that type of cable around in the 60's,
it was war surplus
very heavy duty designed to last
but eventually the rubber breaks down and becomes brittle.
after 50 years I would consider replacement ?

 

[Lucien Nunes]

This is ordinary VIR conduit cable that could have been made anywhere between 1920 and 1960. As per Davesparks it was never supposed to be installed outside of conduit as it is single insulated, so this is likely the work of an amateur who found an old coil of it and decided it would do. Therefore, its condition is immaterial; it needs to go. You might find it's still tough and durable, or it might crumble in your fingers, all depends on the exact formulation of the rubber as to how well it ages. The IR usually remains good, even when it's about to crumble. VIR in good nick often measures better than brand new PVC.

 

[Marvo]

Personally I'd replace any VIR cable on sight, it more often than not crumbles or cracks as soon as it's disturbed.

 

[KennyKen]

Here Here.

 

[dmxtothemax]

where where ?

 

[KennyKen]

You Aussies are Quick

 

[dg2908]

Thanks all, much appreciated.

Dave I'm not that daft- whole circuit has no earths so IR test was L-N with all the lamps out and the switches on

 

[telectrix]

that's horrific. a square edged faceplate on a rounded patresss.

 

[Pete999]

Deleted

 

[The Ghost]

Very often find that cable on re-wires in victorian houses and '30s houses. But usually it is in wooden conduit, rectangular shaped with grooves for the cable.

 

[telectrix]

groovy !

 

[telectrix]

none of that wooden channel in our gaff. it's a fire risk.

 

[westward10]

Very often find that cable on re-wires in victorian houses and '30s houses. But usually it is in wooden conduit, rectangular shaped with grooves for the cable.

Like this.

 

[westward10]

Poly butyl jute insulated cable (PBJ).

 

[The Ghost]

Presactly like that

 

[DPG]

Nob and Tube Tel - the most amusing of the wiring methods