Green slime on cable (ed.)

[Jeremy Home]

Hi
I’ve just moved into a new house, and decided to change the light switches for something more modern.
This is what I saw when I opened the first switch.
It looks like the earth wire sleeve has melted.?
The only thing I have done is changed some wall lights and a ceiling pendant for a flush fitting light.
Both work fine.
There are two light circuits.
Half of the switches in the house have the same issue, and it isn’t consigned to one circuit.
Before I call in an electrician, has anyone seen this before?
It looks pretty serious to me.
Thanks

 

[Mottie]

Doesn’t look like burns to me. I’ve seen my mate, who is an electrician, use some lubricant when doing a rewire if there is some trunking that he can feed the new wires through instead of chopping the wall out. Maybe it’s that?

 

[davelx]

probably Green Slime:

https://www.diynot.com/wiki/electrics:green-slime

 

[crystal ball]

+ 1 for slime

 

[ericmark]

Looks like the plastersizer leaching out of the cable, this was a problem with some cable used in the 70's and it makes the cable brittle, if not disturbed it is normally OK, but in Australia Woolworths it seems imported cable from China and had to pay for house rewires due to plastersizer leaching out, not sure why is was considered so bad there, it was not considered such a big problem here.

It does get worse the warmer the cables are, and other than a rewire not much you can do, I would want RCD's on all circuits to be on safe side and use plastic switches etc. And disturb as little as possible until rewired.

Job one is testing, see if you can fit RCD protection, some times the leakage is too high and RCD's will not hold in, would say go all RCBO so should a circuit go faulty you only loose that one, but in the main it just makes cables brittle so if not touched they are OK.

 

[JohnD]

you're lucky, sparkies love to see the slime. You can wipe it away with a tissue. More will come, though. If it has been able to run into the switch, replace the switch, as it can cause mechanisms to jam. If you can position the wires so they run downwards in the box, and loop upward towards the switch, slime will probably not run into it.

With luck the faulty cable will only be in part of your installation, perhaps from a single reel, maybe just one lighting circuit.

You need to start planning for rewiring of whatever circuits and accessories are affected. The problem will not get better.

 

[crystal ball]

Looks like the plastersizer leaching out of the cable, this was a problem with some cable used in the 70's and it makes the cable brittle, if not disturbed it is normally OK, but in Australia Woolworths it seems imported cable from China and had to pay for house rewires due to plastersizer leaching out, not sure why is was considered so bad there, it was not considered such a big problem here.

It does get worse the warmer the cables are, and other than a rewire not much you can do, I would want RCD's on all circuits to be on safe side and use plastic switches etc. And disturb as little as possible until rewired.

Job one is testing, see if you can fit RCD protection, some times the leakage is too high and RCD's will not hold in, would say go all RCBO so should a circuit go faulty you only loose that one, but in the main it just makes cables brittle so if not touched they are OK.

Sounds like a different and quite recent issue
https://www.voltimum.co.uk/articles/faulty-cable-leaves-woolworths-australia

 

[conny]

The earth lead is the one in green sleeving attached to the back box and it looks ok.
The greeny/yellowy one shouldn't be an earth as it is connected to the switch terminal.

 

[bernardgreen]

Happened 6 years ago

22/01/2015
8 comments

The Approved Cables Initiative (ACI) is reporting that Woolworths may face a clean-up bill of between £16 to £32 million for its role in the sale of faulty electrical cable to around 40,000 households and businesses. This major problem has occurred in Australia, but the risk is that it can happen in the UK:

The cable that Woolworth Australis imported from China was very poor quality, I seem to recall there a criminal convictions for gross negligence by the manufactures and the quality control people at the importers.

 

[JohnD]

The earth lead is the one in green sleeving attached to the back box and it looks ok.
The greeny/yellowy one shouldn't be an earth as it is connected to the switch terminal.

well spotted, at first glance it does look like a G&Y, but it is, I think, the Y from red/yellow/blue old colours 3+E, with green stain.

 

[Taylortwocities]

Yes slime. The wiring looks an appropriate age. Can’t be fixed without rewiring. Can be cleaned off reasonably easily, but don’t leave it too long or you’ll get this sort of thing...

Untitled

• Taylortwocities
• 28 Oct 2008
• 1

Untitled

• Taylortwocities
• 28 Oct 2008
• 1

 

[sparkwright]

Another vote for green slime.

It will not get better.

Re-wire time unfortunately, particularly if you haven't started decorating.

 

[Jeremy Home]

Thanks
That’s been very helpful indeed.
I figured it was the earth cable melting only because the earth is green.
Thank god it’s not.
Fortunately, that was by far the worst switch.
I was looking to have it rewired anyway, but not for a couple of years.
I’ve got a subsidence issue to sort out first.
Meanwhile, If the ends of the wires in the box were cut off, and new wires attached to the ends would that help?
Presumably the green slime wouldn’t be seeping out as much, if at all, in the cable buried in plaster.?
With regards to metal switches.
These should be ok if they’re earthed right?
Thanks

 

[sparkwright]

Thanks
That’s been very helpful indeed.
I figured it was the earth cable melting only because the earth is green.
Thank god it’s not.
Fortunately, that was by far the worst switch.
I was looking to have it rewired anyway, but not for a couple of years.
I’ve got a subsidence issue to sort out first.
Meanwhile, If the ends of the wires in the box were cut off, and new wires attached to the ends would that help?
Presumably the green slime wouldn’t be seeping out as much, if at all, in the cable buried in plaster.?
With regards to metal switches.
These should be ok if they’re earthed right?
Thanks

Fitting new wires to the ends of the old wires isn't really going to help, slime will still come out of the old cables.

As regards to old cables in plaster, slime will still come out of the cables.

The slime escapes through the ends of the cables, and so collects in the back box, and can eventually run out and run down the wall.

If all the earth wires are correctly connected and you can prove you have an effective earth, then you can fit metal switches, ensuring the faceplate is earthed to earth terminal.

Waste of time fitting them if they are going to get covered and full of slime.