Can anyone point me in the direction of some current information relating to the phenomenon of Green Goo (di-isoctyl phthalate) from electrical cable/fittings?
For those who are not familiar, it is a green substance which oozes from electrical fittings and caused by reaction of PVC compound used in cables from mid 1960's to early 70's.
I'm looking for something authoritative - I believe there used to be something by NICEIC, but I can't seem to find anything on their site
cheers
dg
The following statements were attributed to the IEE or NICEIC by the people who posted them:-
Attributed to NICEIC:-
"Green goo is a phenomena sometimes encountered in electrical installations constructed in the late 1960s.
Unsightly green slime can occur in switch and socket-outlet boxes. It is understood that this phenomenon is most prevalent where pvc cables manufactured between 1965 and 1971 have been used. The green slime, or green goo, is degraded di-isoctyl phthalate and is considered to result from a chemical reaction between the plasticiser of the insulation and the copper conductor in the pvc cable. Between 1965 and 1971 the temperature performance of pvc was uprated by the inclusion of an anti-oxidant into the pvc compound. An unappreciated side effect was that the anti-oxidant encouraged production of the exudate.
There is evidence to suggest that high ambient temperatures accelerate the process. The exudate is of low flammability and low toxicity. Although unsightly, it does not reduce the electrical integrity of the conductor or the insulation. However, the exudate may have detrimental effects on both accessories (in appearance and functionality terms) and their surrounding decorative finishes."
Attributed to IEE:-
"It is most prevalent in cables made between 1965 and 1971. The gunge is degraded di-isoctyl phthalate and is the result of the reaction between the plasticiser in the insulation and the copper. Between
1965 and 1971 the temperature performance of PVC was uprated by the inclusion of an anti-oxidant in to the PVC. An unappreciated side effect was that the anti-oxidant encouraged the production of exudate.Evidence suggests that high ambient temperatures accelerate the process. The exudate is of low flammability and low toxicity. Although unsightly it does not reduce the electrical integrity of the conductor or the insulation.
Green exudate from PVC
Draft BCA statement (April 2001)
1) PVCPVC comes in two main grades, plasticised and unplasticised PVC.
Unplasticised PVC (UPVC) is used for example in double glazing window frames where a rigid material is required.
The PVC used for manufacture of cables is a plasticised PVC that conforms to the relevant British Standard for the cable type in question.
2) Ageing effectsAs a cable ages; (at temperatures above normal ambient), the elongation to break decreases (also the Insulation Resistance increases). The life expectancy of a cable is arbitrarily considered to be when the elongation to break of the PVC is 50%. A lower elongation to break value could be considered suitable especially for a fixed wiring cable. Therefore, providing the cable is not subject to movement or when moved due to inspection of socket outlet or the like, the PVC does not crack, a much lower value of elongation to break is considered by some as suitable.
3) GreeningGreening is the appearance of a wet green substance that is a product of an adverse reaction between certain types of plasticiser and the copper conductors. This greening, which is a rare occurrence, can happen either after a long period of time for some cables, or if the cable has been severely overheated. The plasticiser itself is a clear oily liquid that is non conductive. The green substance is a combination of copper oxide and plasticiser which may become conductive under certain adverse conditions.
4) Action if Greening is foundTherefore whenever this green substance is found at socket outlets etc. initially it should be removed and the terminations cleaned (gloves should be used) otherwise it is possible that tracking/overheating may occur. It is strongly recommended that rewiring should be carried out as soon as possible."
Take your pick :-)
That's from an article in a thread in the IEE/IET wiring regs forum, rather than from the institution itself. The whole thread is here:
Green exudate can also be caused by dampness in the socket corroding the copper cable, and this can be confused with the plasticiser issue mentioned in this thread.
NT
ISTR Dr.Who had a problem with green goo in a mini series (John Pertwee).
As Dr he should have known to go to the GU clinic to get it sorted.
Adam
Australia:-
I'm a bit concerned about that Australian link though ..... especially after reading the disclaimer, which amongst other things says -
"The department makes no statements, representations, or warranties about the accuracy or completeness of, and you should not rely on, any information contained on this site"
lol. What is the point of puting it there then?
dg
On Wed, 01 Aug 2007 13:32:55 -0700, dg mused:
Australia:-
Could say the same about the internet and usenet as a whole.
Like I'm going to believe that!
It's made of copper, it's bright green, and the only salt involved is the _oxide_ ? I rather think not. Wear the gloves.
Goos have a habit of trapping dusts, some of which are conductive to some extent. Hence 'under adverse conditions.'
NT
Copper oxide is black. Its the carbonate thats green.
cupric oxide black cuprous oxide red/orange
I thought that was a little too advanced for the chaps..
Any acid will produce various other salts from the basic oxides.
Carbonate is green, sulphate is blue..can't remember what color acetate is and copper chloride/chlorate is soluble IIRC and washes off..
One of the most useful metals when playing the 'maximum number of colored stripes in a test tube, using what's in the chem lab' game ...
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