What is this black tarry stuff on the cable?

[HappyHippyDad]

I have been carrying out an EICR on a property and have come across this black tarry substance on 2 of the cables.

I have seen the pitch oozing out of a cut out before and I don't think it's this. Mainly because I thought that was only on the cut out fuse.

It's also not green, so it's not looking like the green goo.

It's extremely sticky and once it's on your skin, it's staying on until you've spent quite a bit of time scrubbing.

In the photo of the conductors coming out of the socket, you can see it all over the conductors. This circuit had a L/N - E IR reading of 0.36Mohms. There are damp problems in the property, especially at the socket in the picture. However, it is rising damp and the cable in next picture (explained below), is on the first floor on a non exterior wall, so I can't see the damp being anything to do with the black substance.

The other picture shows a 1mm cable sticking out of the wall with the black substance all over the outer grey insulation. This cable is dead and not in use.

Anybody know what the black stuff is?

 

[Rockingit]

Hard to tell exactly but your options are either 1) it's a contaminent that's come from somewhere or 2) it's the plasticiser breaking down chemically. My money's on 2 but neither is great and will almost certainly be affecting the dielectric strength of the insulation.

 

[Pretty Mouth]

Flat roof above? Have seen similar, including it being all over the outer sheath. I put it down to bitumen roof products.

 

[Lucien Nunes]

If it's appearing from within the cable i.e. not something that could have oozed out of the building fabric, then I would agree that it is probably plasticiser escaping from the PVC, but of a type that does not attack the copper and therefore does not turn green. (The plasticiser that causes green goo is actually colourless, only turning green on reaction with copper.) The black might be mould, some PVC cables have a habit of turning mouldy even without visible leaching so it might be worse where it is actually breaking down, especially in a damp environment.

 

[loz2754]

Melted adhesive from the insulation tape?

 

[HappyHippyDad]

Melted adhesive from the insulation tape?

I did think of that. The one constant that I can identify is that they both had insulation tape wrapped around them. Still seems unlikely though.

 

[loz2754]

The fact that it's sticky contributes to my thesis.

 

[James]

I thought it looked like old insulation tape.

 

[davesparks]

Looking at the exposed bits of wall in the picture with the cable sticking out could it be that the wall has been painted with blackjack or some other sticky black shmooo to waterproof it before being plastered? If so the messy sods have probably spread it over everything, cables included.

 

[HappyHippyDad]

Well noticed. There does appear some odd black painty stuff. Perhaps an attempt to decrease damp seeping through.
I'll do the fault finding and hopefully dig up some more clues.

Looking at the exposed bits of wall in the picture with the cable sticking out could it be that the wall has been painted with blackjack or some other sticky black shmooo to waterproof it before being plastered? If so the messy sods have probably spread it over everything, cables included.