# Forum Home Renovation Electrical  Green Ooze in wiring

## m6sports

I was painting today and i needed to take unscrew a light switch so that i wouldnt paint over it 
and thought to my self while its off i will change it to a new one because it had a crack in it  BTW i know i should change it my self as im not a sparkie
but to my surprise i found green ooze coming from the copper wiring 
is this normal or is rewiring the house somthing i need to be thinking about

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## nev25

> i know i should change it my self as im not a sparkie

   :Shock:  Naughty Naughty Naughty 
Without seeing it I would guess you have old cable with aluminum conductors 
Ive come across this a few times and was wondering the same thing
I asked an old very experience Electrician who told me they used to paint the end of the aluminum conductors where they where terminated in a copper terminal with a blue substance (he did tell me the name but it was a while ago) to stop things like electrolysis/corrosion etc caused by dissimilar metals 
I'M tipping the copper has turned the substance Green 
Ive seen this a few times mainly on neutral bars (old ones) 
In my opinion if you have aluminum conductors you should be looking at a rewire 
BTW what colour was the sheath (white or black)

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## m6sports

it had Black Sheath
and yea i know i was Naughty but i survived to live another day  :2thumbsup:

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## Master Splinter

From Olex Cables -  http://storage.baselocation.com/olex...503640c2d7.pdf  (PDF file - useful cable info too!)  
"What is Green Slime or Goo? And do I need to re-wire circuits with Green Slime coming out of the wires?   
Also known as "Green Slime", this phenomenon is characterised by the appearance of a sticky green exudate leaking out of PVC-insulated wiring at locations such as switches, hot points and light fittings. The green goo problem is predominantly associated with older (25+ years) TPS-type cables operating in a warm environment. The exudate comprises a plasticiser that has migrated out of the PVC insulation, coloured due to reaction with the copper conductor.  
Due to its stickiness and unsightly colour, the goo has a high nuisance value, however it poses no significant health hazard. It may be cleaned from surfaces by wiping with a rag soaked in a petroleum- or alcohol-based solvent (such as meths).  
The long-term consequence of the exudate is that it represents a de-plasticising of the insulation, meaning that as the process continues the PVC will eventually become brittle, and crack."

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## nev25

> it had Black Sheath

  Yeah I would be tipping it rubber and not PVC 
The problem with the rubber sheathing is it goes brittle and crumbles over the years and eventually leaves bare exposed conductors especially when its moved as in where fitting have been replaced. 
I would suggest a rewire might be on the cards

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## m6sports

Master Splinter is it somthing to worry about

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## Smurf

I've seen it quite a few times in roofs, mainly in warm situations such as cabling that's a bit too close to wall ovens, heater flues or other heat sources. 
With PVC (white) cable it's simply a case of the PVC gradually "wearing out" and eventually the wiring will need replacing. But just because there's a bit of green doesn't mean it's actually worn out - yet. It just means it's getting older. A bit like anything that's nowhere near new but isn't necessarily due for replacement yet. 
Anywhere there's corroded copper you'll find some green residue. Old copper power lines are a classic (new ones are aluminium) and also you'll see it on pipes, old copper water heaters etc. Copper "rust" is green in the same way iron rust is brown. If you end up with underground cables becoming heavily saturated with water over a prolonged period (eg an abandoned cable) then the whole thing ends up a mass of green inside if you strip back the insulation. Just like a piece of steel would end up a mass of brown rust. 
Back to the cable, if its black insulation then odds are it's rubber and well past its use by date anyway. Only once in the past few years have I found such cable in what I would call "good" condition, nearly always it's getting brittle and a re-wire is needed. Two choices with it really - call an electrician now and have it replaced or alternatively leave it for a few years and call the fire brigade instead. Personally I'd go with the re-wire.  :Smilie:

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## m6sports

ive just looked at some other wiring that the sparkie removed from a power point when we knocked down a wall and its also got that green ooze 
i will post some pictures of the wire tomorrow

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## Master Splinter

I'd be thinking long and hard about a rewire in the very near future.

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## Bros

> From Olex Cables -  http://storage.baselocation.com/olex...503640c2d7.pdf  (PDF file - useful cable info too!)

  Thanks for that info it explains a lot. A couple of yrs ago my Sister in Law showed me some GPO's that had the green goo coming out and I was puzzled. I took the GPO off and all looked fine but it could be traced back to the cabled which leaked out of the GPO.
By coincidence the GPO's were wired in PVC and would be about 25 yes old but no more and is on the western side of the house the hottest part.
Not great for cable that had a rating of 75 deg C

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## juan

One cause of copper discoloration is the effect of anhydrous ammonia. It reacts with copper resulting in a blue / green discoloration of the copper. Anhydrous ammonia is a key ingredient used in the manufacture of methamphetamine. Is your lab in this room?

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## LordBug

> I asked an old very experience Electrician who told me they used to paint the end of the aluminum conductors where they where terminated in a copper terminal with a blue substance (he did tell me the name but it was a while ago) to stop things like electrolysis/corrosion etc caused by dissimilar metals

  Might've been a lanolin based product. I've known a few cockies in the past who slathered it onto battery terminals to stop them corroding.

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## m6sports

Here are those pictures they arnt great quality but you can see a green 
coating on the red wire

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## Master Splinter

Eeewww - at least the old stuff will function as a pull through for the new wire (which is smaller in insulation size these days, so it should be easier to pull through).

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## nev25

Huh   

> it had black sheath

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## Smurf

I recall one instance of a PVC insulated cable simply snapping in two for no apparent reason. It just went open circuit, seemingly without being touched in any way.  
That wasn't a good situation as it was an underground mains cable out in the street, the conduit running to and up the pole was blocked and this was at night in the middle of Winter...  :Cry:  
Temporarily it was fixed by a join until the street could be dug up and the cable replaced at a more sensible time than midnight. We had to be pretty careful joining it though to avoid snapping it again. Both the insulation and the copper were incredibly brittle. 
That's the only time I've seen this but if it can happen once then it's not impossible that it could happen again. We were pretty confident that there had been no overloading of the cable based on cable size, protection rating and the actual connected loads. This was a couple of years ago and I'd guess that it was originally installed sometime during the 1970's or maybe late 60's.

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## m6sports

> Huh

  sorry im no sparkie when you ment black sheath i thought you ment inside the 
white out side sheath lol

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## 2x4

Your cabling is not rubber sheathed.This older style type of cable is sub standard. 
The cable in the picture, while not modern, should be fine for many more years. 
The only true way to know for sure is to get your sparky to throw a megger over the sub circuits to check the integrity of the insulation. 
While he is there , get him to check out the size of your mains, commonly run in 6mm up untill the 1980s.(ish) Standard requirments know is minimum 16mm. This can be quite important as we are prone to little luxuries such as new bigger kitchen appliances/ whitegoods/ reverse cycle aircon etc. etc.   
.

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## Bloss

This is simply verdigris - will occur on any copper (not aluminium) exposed to air and some moisture. 
Verdigris is the common name for the green coating or patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea will be a basic copper chloride.[1] If acetic acid is present at the time of weathering, it may consist of copper(II) acetate. 
This is a common site on the backs of old switches & power points and as has been said the stickiness is from the breakdown of plasticisers in PVC insulation or the rubber in older cables. It is common to see ants around the back of switches and power points that have verdigris exudations - sometimes in enough numbers to cause arcing and shorting. Not sure why they like it. In fact some cloudy ammonia will wipe it off the end of the wire, but sometimes the verdigris has moved quite a way down the cable. Usually not though - the sparky will usually trim the cable back to clean wire, brush off the green muck and re-attach the wires. Not a DIY job! 
BTW - that cable is not 'sub-standard' - it is a very common compliant cable with twin & uninsulated earth used until the late 70s and in some places into the 80s. Because the earth was not tightly covered in insulation it has had some verdigris form - it has simply stained the plastic. This will not affect the conductivity or the safety of the cable although as I said the connector and cable should be cleaned and re-tightened - like many electrical safety issues it's poor termination that can cause problems. Of course stripping away the outer insulation means that piece is no longer usable.

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## m6sports

Thanks guys for all the advice 
might sleep a bit better knowing its not at bad

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## suzerz

> I'd be thinking long and hard about a rewire in the very near future.

  Due to the green goo?

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