Wire rot

10-10-20

I suspect I know what this is, but I'd appreciate the opinions of others also.

My parents house was built in 1973 and no major modifications were made until recently.
I just noticed yesterday that under the kitchen light switch there is a distinctive green patch appearing, and growing.
I opened the switch housing and found that the green substance was of an oily nature, appearing to have taken the green colour from the corrosion of the copper wiring. Seemingly the oily substance is leaching from the plastic insulation on the wires and running downwards as dictated by gravity.

To prove that this wasn't a one-off event, I opened another switch plate and noticed the same substance, but less of it, in another room.

Is this common in 35 year old wiring?
Any idea what the substance is?

There isn't an RCD on the fuse box, should I be thinking of getting one installed for them?

crosstownk

I'm no electrician but given the age of the wiring I'd hazard a guess that you are correct in saying it's corrosion of some sort. Maybe a rewire might be the best solution - but I'll leave the final word to any baords electricians who care to comment.

eoghan.geraghty

It might be time to start pricing for a rewire.
I've never seen the type of decay you're describing but would agree with your preliminary diagnosis.
It won't cost anything to get some quotes and the visit by each electrician should confirm your suspicion or provide alternative explanation.
Good luck.

Alun

I've come across this before, and the gunk you're seeing is the plasticizer used in making the PVC insulation being released from the PVC and seeping out, reacting with the copper of the wire.

Plasticizers are the chemicals added during the manufacture of PVC that make it flexible. When the plasticizers seep out, the insulation can become brittle, and crack. Most common cause of this is heat, often due to overloading circuits, but they can also be released under the influence of heat from other sources or in the case of fire.

The plasticizers themselves, especially from that era, are highly toxic and carcinogenic, so be careful (Google DOP or DEHP + plastiicizer for more info).

Copper

As Alun said, the plasticiser leaches out of the insulation making the insulation very brittle. The cable will sit there fine but if it is disturbed, the insulation may crack which can be dangerous.

Also, over time the connections will have worked themselves loose so a rewire is probably a good investment, especially if its been over 30 years since it was installed.

10-10-20

Great, thanks for the replies. It all fits together now!

So, any guesses on a price for a re-wiring of a 2-story 4 bed house?
€15k?
Does that include re-gluing 7 layers of floral and wood-chip wallpaper?

delly

My mothers house had this happen a few months ago, again built in the '70s. She never really worried about it, but judging by comments a rewire may be needed. Brothers a sparks which helps.

eoghan.geraghty

10-10-20 wrote:

Great, thanks for the replies. It all fits together now!

So, any guesses on a price for a re-wiring of a 2-story 4 bed house?
€15k?
Does that include re-gluing 7 layers of floral and wood-chip wallpaper?

15k would be very expensive.
You can always redecorate downstairs first, followed by the bedrooms as you can afford it.
Its never a bad time to replace floral and woodchip wallpaper:D

kilasser

My house was built in the 70's. Just had a shower and extra sockets in the kitchen put in. Ive got this green stuff also, the electrician told me that it is a very common with installations done in the 70's and it was caused by a reaction between the copper wires and the plastic coating. He also said that theres was no problem at all and that the wireing is fine as it is as long as its not ingested by a person.

crosstownk

I had my house rewired 18 months ago. It's a 2 storey 4 bed. It cost €5300 in total and the amount of 'damage' done to the walls etc was minimal.

pat127

kilasser wrote: »

My house was built in the 70's. Just had a shower and extra sockets in the kitchen put in. Ive got this green stuff also, the electrician told me that it is a very common with installations done in the 70's and it was caused by a reaction between the copper wires and the plastic coating. He also said that theres was no problem at all and that the wiring is fine as it is as long as its not ingested by a person.

I hope it's ok to re-activate an old post but it's the only one I can find relevant to my query. I had a small job done on my 1972-built house and the electrician pointed out this oily substance, warned about its health dangers and the associated risk of fire. He said that copper being dear at the time, builders used inferior Turkish and other foreign-made cable. His boss used a meter of some sort to test the wiring and said the readings were very low ("0.2 instead of 0.8"), that the house was a fire hazard and the wiring should be replaced. Said also that insurance companies won't necessarily pay out in the event of an associated fire.

Is all this likely to be correct? What sort of meter was used - one for measuring the strength of the insulation? Should I seriously be considering a re-wire (€5,900) 4-bed detached? Is there a way of getting an objective assessment?

Many thanks

meercat

pat127 wrote: »

I hope it's ok to re-activate an old post but it's the only one I can find relevant to my query. I had a small job done on my 1972-built house and the electrician pointed out this oily substance, warned about its health dangers and the associated risk of fire. He said that copper being dear at the time, builders used inferior Turkish and other foreign-made cable. His boss used a meter of some sort to test the wiring and said the readings were very low ("0.2 instead of 0.8"), that the house was a fire hazard and the wiring should be replaced. Said also that insurance companies won't necessarily pay out in the event of an associated fire.

Is all this likely to be correct? What sort of meter was used - one for measuring the strength of the insulation? Should I seriously be considering a re-wire (€5,900) 4-bed detached? Is there a way of getting an objective assessment?

Many thanks

the electrical section may be better for this(mods may move it for you)
i would imagine he done a megger test(insulation resistance)
if your house was built in 72,it is probably due a rewire anyway
think the bit about turkish wire was misleading
i have seen this green oily substance before which is an indication of the insulation breaking down
i would advise getting a couple of registered contractors to look at your installation and quote you on a rewire
i think that the insurance company reference was a bit of scare tactics,however it has been known for them to require a test of some older installations in order to secure insurance

i would expect that the electrician is right however ,when he says a rewire is required

pat127

meercat wrote: »

the electrical section may be better for this(mods may move it for you)

i would advise getting a couple of registered contractors to look at your installation and quote you on a rewire

Many thanks. I've contacted a couple.