black sticky liquid??

[Dean Williams]

Hi
while testing a DB in a primary school today, i found all the conductors within the DB coated in a black sticky, tar-like goo. see attached photos. im assuming its the conductors overheating and the insulation melting. can anyone confirm this. If that is the case, i can't understand it. there are no significant heat sources nearby apart from a stage lighting DB below, which i switched on with all the spotlights on full and left it all day to see if it produced any heat, which it didnt.
any help would be greatly appreciated.
cheers guys

 

[SirKit Breaker]

Something may have gone bang at sometime or other in the past within the enclosure. I have seen it before, as long as everything tests out OK, and there is no obvious damage, then i would isolate it, and give it all a good clean with solvent cleaner, then have another look.

Cheers........Howard

 

[imago]

What's above the DB? I saw one in avery similar state a few years back which was also in a primary school oddly enough. To cut a long tale short after the intitial worry, some questions, a look above the ceiling and some more questions, it turned out that the roofers had spilt a tin of felt sealant over the board from above. It had been isolated and cleaned up to about the state that looks. ie not very well.

 

[Dean Williams]

theres nothing above, just an empty roof void. but something may have gone bang. i say this because all of the MCBs and RCBOs are the same except one, which is a new one. The IR readings were quite low. of the 9 circuits, 4 were >200M, 2 were between 2 and 4M, one was 1.15M and the last 2 were about 0.96M.

 

[Des 56]

It could be tar or such from an unrelated job
What doesn't look good is that hole that has been cut with all those jagged edges where the conductors pass through

 

[Dean Williams]

The hole has been noted. the cables drop down a length of plastic trunking to the board, the board is halfway up the wall. the cables in the trunking are all ok

 

[Dean Williams]

i got the stuff on my hands, it took ages to get off.

 

[Des 56]

i got the stuff on my hands, it took ages to get off.View attachment 11583

Or was it that the toilet paper was extra thin

 

[Top Cat]

Just a thought, i had something similar a while back, but this was more a greeny black goo.

I found out that the installation had lost it's neutral so all power was flowing to earth and the earth wires were overheating causing the PVC to have some sort of reaction.

 

[Dean Williams]

i thought that at the start, but ruled it out because the neutrals are in the same mess

 

[Dean Williams]

going back to the theory that something may have exploded in there, the only wire not coated is a neutral from a new RCBO. but that may just be a coincidence.

 

[D80]

Are you able to see what the conductors look like before they enter the board?

Board looks like a shambles too

 

[Dean Williams]

yes. the conductors are all ok.
where the conductors terminate, the bare copper is still shiny, not blackened like from overheating.

 

[D80]

So no black stuff before they enter board?
Not a lot of black stuff on the board, just on all of the cables in it.

Not got a clue what it could be. I'm gonna have a pint of the blackstuff and hopefully get educated on this one.

 

[Guitarist]

May sound like an odd q, but what does the black stuff smell of?

 

[Kiers1970]

Glad its not sticky white stuff.

 

[Guitarist]

If you were a real detective, you would taste it too, but I don't recommend that :wacko:

 

[J&M Electrical]

It was all over the old cables on a rewire we did last week, however the mainsboard was fine and it was at the sockets that this black goo occurred. Could it be something in the PVC outer sheathing that has failed over time?

 

[Dean Williams]

it doesnt smell of anything. the wiring is 20 years old

 

[Guitarist]

it doesnt smell of anything. the wiring is 20 years old

It's amazing how many decades certain smells can linger. If it's still sticky and anything oil-based (ie. insulation etc) I would expect it to have a pungent smell. Maybe at some point in the distant past, a teacher or cleaner used it as a shelf and something leaked inside.