Sockets wired in black rubber query

[Welsh_sparky_21]

testing a property there, the sockets were wired in black rubber 2 core with bare stranded earth coming into the boxes. Done all the Ring tests and everything was fine, continuity between all conductors and R1+R2 fine also. Just wondering is it safe because you got the 2 core cable without a cpc within the cable?

 

[brianmoooore]

Is this relatively new cable or something that looks like it pre dates PVC?

 

[Welsh_sparky_21]

Is this relatively new cable or something that looks like it pre dates PVC?

Pre dates PVC definitely

 

[Farmelectrics]

is it VIR cable. are there any signs of it breaking down, im gathering not if the readings are ok.

 

[Farmelectrics]

if its VIR cable i would still recommend it gets replaced.

 

[Lucien Nunes]

Do you have any pics?

If it is traditional VIR it will be 60+ years old and while some of it looks fine, other parts with different environmental exposure might have failing insulation. It is possible for the rubber to harden and crumble away leaving exposed conductors, without affecting the IR test result. So it is now considered good practice to recommend replacement even if the test suggests it's fine. The separate CPC is technically a non-compliance if it is too small for a single unenclosed conductor.

 

[brianmoooore]

Separate earth wire would need to be a minimum of 2.5mm2 if mechanically protected, or 4mm2 min. if not. No problem with the cpc not being part of the supply cable, but this stuff is from the '60s at best. Time it was gone.

 

[Welsh_sparky_21]

What I initially put down was that it was testing fine but that the cable was old and would recommend upgrading. I’m always unsure when I come across a type of cable I’ve never seen before. House was built in 60s so it must be in from then, lighting circuit has no earth also

 

[suffolkspark]

There was a paragraph in approved document p saying VIR cable is past its operating life and should be replaced, nothing specifically in bs7671 but id struggle to give it less than an FI and would want to inspect every inch, probably bi annually, in practice, with the other issue you mention it sounds like it needs a rewire

 

[brianmoooore]

It's not unusual to come across sections of this kind of cable, several inches long, where the rubber insulation has completely disappeared, leaving just parallel bare copper wires. IR tests absolutely perfect, because dry air is a very good insulator, but hardly safe.

 

[telectrix]

rip it out,weigh it in, replace with pvc/pvc.

 

[Welsh_sparky_21]

agree 100%. I wouldn’t feel comfortable if I knew this type of wiring was in my house