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.

 

[Edd]

cables dont run through a roof space and been pulled through roofing tar, and the poor sparks got covered and couldnt be bothered to clean it off befor doing the board.. been covered in sticky crap like that before and got it everywhere, just dont come off

 

[Dean Williams]

thats a good point. the school has a flat roof and most prob has had bitumen or something on it. i'll have a search tomorrow.

 

[Darkwood]

Couple of points here, doing my csi... the likely cause is leaching of plastercisers out of some of the older cables, the majority in your picks is second hand contact (transfer) probably caused by other sparkies getting it all over their hands like yourself too, for the plastecisers to leach out their has to be a chemical reaction and may have taken decades this could all come down to the original installers greases the wires to drag them in or as mentioned before the tar issue is a likely cause too, if they were dragged through tar (even set tar) they will have black streaks rubbed onto them, tar reacts with the pvc causing leaching of the plasticisers which in turn liquifies the tar to a sticky goo. The issue is that when the plastisicers leach the cable insulation can change it properties for the worse, ive seen insulation showing 230v to earth before where leaching occured.

 

[Darkwood]

Or the obvious one is the previous sparky left his bag of liquorish allsorts on top of the dist board,....... give it a lick :wink_smile:

 

[Dean Williams]

cheers Darkwood. most of the goo was tacky, but some had set a bit and when i picked it off, the insulation came off too. i originally thought that it was some sort of plasticiser migration, i saw a similar thing at a theatre i tested last year, except it was green goo...the dreaded migration of the plasticiser di-isoctyl pthlene.

 

[SPARTYKUS]

my money is on roof tar, awful stuff.

What a mess!

Just spray a can of WD40 into the CU........ !

 

[Darkwood]

Its always hard to pinpoint without knowing the full history but i do recall seeing old pvc cables run over tar in a cellar and it layed in a line of sticky wet tar where the rest was solid, its seems that both react to each other and yes its a 'bitumen' to get off your hands (see what i did there! lol).... , but im on the understanding modern cables dont suffer like the old stuff but are prone under the right conditions.

 

[Darkwood]

my money is on roof tar, awful stuff.

What a mess!

Just spray a can of WD40 into the CU........ !

Only if your trying to blow it up!!!!!!!!! I seriously hope this is sarcasm!!!!

 

[SPARTYKUS]

Darkwood


Worry ye not. Meant to be sarcastic!


Want a quick flamethrower? One match, can of WD....

 

[Darkwood]

Darkwood


Worry ye not. Meant to be sarcastic!....

A emoticon of destruction would have been nice on this one as it can come across as advice to those who dont know its conductive, flamable and eats many types of plastic even i had to check your post was siding with humour.... ive seen an apprentice turn a motor into a ball of fire before with WD40! :willy_nilly:

 

[vernam616]

With you mentioning it was a school is the cabling ran in conduit?

Once had a job where there was a greeny black goo on the conductors just like that in your photo, turned out it was a lubricant they used years back to pull cables through the conduit easier

 

[ackbarthestar]

I remember a job we did. Before the galv conduit was buried in concrete we poured bitumen over all conduit and trunking system. Now if there was conduit set in the flat roof some of the tar may have seeped into a part of it and when the cables were pulled through at a later stage had picked it up. rather than cleaning it up the installation sparks just left it as is.

 

[jimmymac]

I think it's Anti-climb paint, formaly known as Vandal grease. One of my mates is a school janitor and he's always covered in it. I bet the jani was poking around in the DB with his paint brush

 

[Dean Williams]

Thanks for all your replies. After a bit of searching today i found the culprit. as most of you said, it was.....wait for it........Bitumen.
i got into the roof space and found it had dripped down walls and was all over the place.

 

[SPARTYKUS]

A emoticon of destruction would have been nice on this one as it can come across as advice to those who dont know its conductive, flamable and eats many types of plastic even i had to check your post was siding with humour.... ive seen an apprentice turn a motor into a ball of fire before with WD40! :willy_nilly:

You know what, you're right, sorry should have made sure blindingly obvious!

Point taken darkwood. :82::82::82: