ADVICE PLEASE - SURFACE CONDUIT SYSTEM FOR REWIRE 3 BED SEMI FRC

[marconi]

I am heading off next week to visit my parents (84 and 83). They live in a nicely decorated and carpeted 3 bed semi with original wiring from 1965.

I noticed last time I visited they have the dreaded green goo in the 7/029 wiring. The 1/044 lighting does not have it. They only have one or two single un-switched sockets in each room apart from kitchen and side extension which are all new and on separate circuits to the original sockets.

The advice I am seeking is on a good, neat, easy to install surface conduit system to contain wiring for new radials/rings upstairs and downstairs in the 3 bedrooms, hall, landing, lounge and dining room. I can then present it to my father and explain the benefits and ease of installation. Neither would cope with floorboards being lifted and walls chased. He is a chemist and read what it says about green goo so I don't need to convince him it's time to re-wire and at the same time to add more handy sockets higher up.

 

[dksanders]

RUBBISH, it has no detriment to the cable what so ever, we are talking about PVC, the life span is infinity. providing its not subject to over heating. etc

Cloud cookoo land calls, 1) see my photos, it is detrimental to the cable 2) nothing has an infinite life span (except stupidity it seems) 3) The manufacturers only warrant cable for 20 years, it may last longer but they won't warrant it, doesn't sound infinite to me.

 

[Deleted member 9648]

In the first two pics there doesn't seem to be any goo that I can see, in fact the wires look deliberately nicked.

 

[telectrix]

think after IR testing giving good readings,leave well alone.

 

[DPG]

Cloud cookoo land calls, 1) see my photos, it is detrimental to the cable 2) nothing has an infinite life span (except stupidity it seems) 3) The manufacturers only warrant cable for 20 years, it may last longer but they won't warrant it, doesn't sound infinite to me.

Anyone who thinks twin&earth will only last 20 years is living in cloud cuckoo land.

 

[7029 dave]

@dksanders , those conductors have been nicked in all your pictures, due to the shallow back boxes.IMO

 

[dksanders]

In the first two pics there doesn't seem to be any goo that I can see, in fact the wires look deliberately nicked.

If you look carefully (zoom in) at that you think is a nick, you'll see that the break then splits down the conductor, this picture shows it better and also the green goo that has formed on the conductor and is running down the inside of the insulation. That's what I mean about you can't see, tell or know, what's inside or underneath. In this particular installation the goo had started to form on the conductors and had made the insulation brittle but was only oozing out on some of the cables. It was that characteristic machine oil smell that made me look closely.

 

[dksanders]

Anyone who thinks twin&earth will only last 20 years is living in cloud cuckoo land.

Please note, I said 'manufacturers warrant for 20 years', not that I believe it only lasts 20 years.

However from Eland Cables: "The standards that cables are manufactured to do not specify a particular life expectancy. Some cable manufacturers will determine a likely life expectancy based on typical conditions. For example a household fixed wiring cable with typical electrical loading, wired using the appropriate wiring guidelines, could be expected to last 20 years."

From The IEE:
"Commentary on IEE Wiring Regulations 16th Edition BS 7671 : 2001

TABLE 6 Life until deterioration against conductor core temperature

Estimating the life of a cable can only be approximate because of the obvious difficulties in accumulating data. There is a general understanding that p.v.c. cables with a continuous conductor operating temperature of 70 °C have a life of 20 years. There is also a rough guide that for each 8 °C increase in core conductor continuous operating temperature above 70 °C the life of the cable will be halved. A p.v.c. cable running with an overload such that its core conductor temperature is 78 °C will last for 10 years "

 

[telectrix]

If you look carefully (zoom in) at that you think is a nick, you'll see that the break then splits down the conductor, this picture shows it better and also the green goo that has formed on the conductor and is running down the inside of the insulation. That's what I mean about you can't see, tell or know, what's inside or underneath. In this particular installation the goo had started to form on the conductors and had made the insulation brittle but was only oozing out on some of the cables. It was that characteristic machine oil smell that made me look closely.

View attachment 39677

bit of heat shrink on that will last till well after the cheque has cleared.

 

[dksanders]

bit of heat shrink on that will last till well after the cheque has cleared.

Hahaha, is that the Scouser Sparky Expertise (SSE) way of doing it....?

 

[123]

@dksanders I've never seen green goo in that form. And if the Green/Yellow sleeving is from the time of install, I've never seen it cause an issue in cable as modern.

TBH only ever seen it in imperial T&E

 

[KEV 1 N]

Dodgy cable I reckon....look at the neutrals, they appear unaffected.
I’ve seen a similar effect on LSF t&e wired in some 2D fluorescent dish style light fittings. The heat had turned the red cable insulation pink/white and was brittle, the black cables were unaffected yet were exposed to the same elements.

 

[telectrix]

those pics are a conundrum. it's not green goo. the exposed copper is oxidised.there must be some other explanation. green goo syndrome has never been seen since the advent of solid core metric T/E.

 

[dksanders]

those pics are a conundrum. it's not green goo. the exposed copper is oxidised.there must be some other explanation. green goo syndrome has never been seen since the advent of solid core metric T/E.

I have to disagree there, all the green goo i've come across has been in solid T&E, I think I've only ever found it in twisted once or twice. The green copper is from the goo forming from the inside out, not oxidisation, the splits opened up as I pulled the plate away, as I said the smell was a dead give away. And as seen in the other picture where the goo was very visible, these were all from the same installation, wired at the same time, when the PVC plasticiser was at fault so quite likely for most of the cables to be effected as shown.

On one switch, as I pulled the plate away from the wall, the core insulation just fell off in big pieces it was so brittle.

 

[marconi]

Update - I visited my father and went through this thread with him. Three stage approach - a friend in his angling club is an electrician and will ask him to do or someone he recommends to do an EICR. Then he will get some estimates of what the outlay and disruption will be. Then we will have another chat. Progress.