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.

 

[Spoon]

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.

But wouldn't surface trunking/conduit make the place look tacky/nasty???

 

[Pete999]

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.

Difficult to say Mate without eyes on the house, my choice would be PVC trunking, but as Spoon said it will not look nice in a domestic setting, but definitely trunking over tube any day, where do they live?

 

[Andy78]

For a domestic surface rewire I would go for trunking over conduit any day, using D-line clips inside the trunking.

 

[DPG]

There's some nice rounded trunking available these days. Looks much better than the standard stuff.

 

[Strima]

You need to consider cable support to prevent premature collapse in the event of a fire, @Andy78 has mentioned D-Line clips to help overcome this.

 

[Wilko]

Hi Marconi - have a look at these
D Line Mini Trunking PVC White Self Adhesive - https://www.tlc-direct.co.uk/Main_Index/Trunking_Pvc_Index/Dline_White_Index/index.html

 

[KEV 1 N]

I remember years ago, we rewired some flats that had concrete ceilings. We used cornice trunking....

....although we chased the wall upto the top, then fed cables through back of trunking, but as shown you can get adaptors for drops to points.

 

[freddo]

We fitted a load of MK coving trunking, hated it a lot.

How about surface bare MI? Unobtrusive, won't collapse in a fire or produce toxic smoke like plastic conduit and trunking does, fun to install etc.

 

[Des 56]

Use mini trunking and wire atop skirting boards wherever possible.

 

[Deleted member 9648]

Given the age of your parents it may be worth thinking about just living with it if test results are satisfactory. In my experience it rarely causes any real problems. New accessories if contaminated, and a clean up might be enough to nullify the problem for the time being. A surface rewire will be a short term solution in reality and will always look cheap however it's done.

 

[Sparkie30]

i would do it next time they go on away and can do all the chasing aswell me thinks.

 

[1Justin]

Your chemist father doubtless understands the nastiness of the Dioctyl Phthalate, but a surface rewire will leave all that in place anyhow won't it?
If it's dripping out of the fittings (that does happen) I can understand the point, but though the cables get soft and a bit vulnerable in the areas it collects (bottoms of vertical runs mostly), in my experience they don't fail IR.
- Wear gloves and don't handle it!

 

[123]

How are the cables installed at the moment? I know most installs from around that era in my area would have been in oval or round steel conduit

 

[7029 dave]

Wait, just because you have the green stuff, does not necessary need to rewire, my suggestion would be wipe it off and IR the circuits. 7/029 pvc is better than the cable today. (I take it its copper)

 

[7029 dave]

 

[marconi]

Given the age of your parents it may be worth thinking about just living with it if test results are satisfactory. In my experience it rarely causes any real problems. New accessories if contaminated, and a clean up might be enough to nullify the problem for the time being. A surface rewire will be a short term solution in reality and will always look cheap however it's done.

So if after some FRC testing including IR the readings are satisfactory, one could keep the cabling (for my parents remaining lifetime) and renew the accessories. Could you tell me a little more about how this might be done please? Do you have to cut back the cable, splice on new tails and then connect these into the new accessories? Is there a best way of doing it? Afterwards, would one have to do regular FRC testing to check for any deterioration?

 

[marconi]

How are the cables installed at the moment? I know most installs from around that era in my area would have been in oval or round steel conduit

A loop around the first floor and then drops down from first floor sockets to the sockets immediately below on the ground floor. Drops in metal conduit. First floor threaded under the floor boards. Copper 7/029.

 

[Pete999]

So if after some FRC testing including IR the readings are satisfactory, one could keep the cabling (for my parents remaining lifetime) and renew the accessories. Could you tell me a little more about how this might be done please? Do you have to cut back the cable, splice on new tails and then connect these into the new accessories? Is there a best way of doing it? Afterwards, would one have to do regular FRC testing to check for any deterioration?

As 7029Dave said it could be after testing that the cables are OK.
Changing accessories shouldn't be that arduous, you could change the single sockets for doubles, surface or flush, your choice on that issue.
You might like to think about a CU change with RCBOs, your elderly Parents have lived with these issues for a while, whilst I'm not discounting the safety issue, it would be a bit of an upheaval to put them through the trauma of a rewire at their age, not saying it shouldn't be considered, but there are things you can do to improve their twilight years, good luck whatever you decide.

 

[Midwest]

So if after some FRC testing including IR the readings are satisfactory, one could keep the cabling (for my parents remaining lifetime) and renew the accessories. Could you tell me a little more about how this might be done please? Do you have to cut back the cable, splice on new tails and then connect these into the new accessories? Is there a best way of doing it? Afterwards, would one have to do regular FRC testing to check for any deterioration?

From what I've seen and read, once it starts, there's no way of stopping it from coming back, even after cleaning.

However, I do agree with the others, the stress of a rewire could be too much for some elderly people. My departed father-in-law got stressed out, when they got a new washing machine. If you put yourself in their shoes, what would they gain from a rewire?

 

[telectrix]

agree with last couple of posts. clean up , fit new sockets etc. the green goo may be unsightly, but it will take years for the cables to deteriorate enough to need replacing.

 

[dksanders]

Given the age of your parents it may be worth thinking about just living with it if test results are satisfactory. In my experience it rarely causes any real problems. New accessories if contaminated, and a clean up might be enough to nullify the problem for the time being. A surface rewire will be a short term solution in reality and will always look cheap however it's done.

As the green goo makes the insulation brittle and fall off, exposing live conductors which can then cause fires or electric shocks; 'living' with it may be short lived.

 

[dksanders]

agree with last couple of posts. clean up , fit new sockets etc. the green goo may be unsightly, but it will take years for the cables to deteriorate enough to need replacing.

but haven't the cables been there years already? How can you tell what the condition of the insulation is in the cables you haven't seen yet? This would be a C2 on an EICR. The way I work is if I find anything that has the potential to cause injury or fire, then it's got to be put right,; there's no brushing it under the carpet and hope it works out OK.

 

[Deleted member 9648]

As the green goo makes the insulation brittle and fall off, exposing live conductors which can then cause fires or electric shocks; 'living' with it may be short lived.

It may do in exceptional circumstances, but I've seen installations where it's running with the stuff and yet cable appear and test fine, I have never once seen PVC insulation falling off in association with green goo. I think your apocalyptic prediction of fire and brimstone if it's not tackled immediately is a tad far fetched.

 

[KEV 1 N]

I came across this stuff on some lighting circuit cables, wasnt expecting IR readings to be high, but to my surprise they were >299 Mohms.

 

[7029 dave]

As the green goo makes the insulation brittle and fall off, exposing live conductors which can then cause fires or electric shocks; 'living' with it may be short lived.

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

 

[Dozer 73]

You can buy single to double even quadruple socket converters , I have used them years ago on council upgrade works they are really good , as long as you buy a half decent make , google it , I’ve added a link to one
Robus Socket Duplicator - https://www.electrical2go.co.uk/led-group-socket-duplicator.html?utm_source=google_shopping&gclid=EAIaIQobChMI-ILEkpvc1wIVhpPtCh1vrQrXEAQYCCABEgJXOPD_BwE

 

[marconi]

Thank you to all who have contributed their advice, recommendations, experience and opinions - all very helpful.

 

[baldelectrician]

I would suggest keeping the wiring as is now (if it tests OK) and doing a consumer unit upgrade / bonding. Maybe even an RCBO board to make it easier for your dad (as he won't be paying labour anyway )
Just replace the accessories for new ones (I prefer Hager) and leave alone (assuming it is safe)
No matter what you do surface it will look worse than what they have now

 

[dksanders]

It may do in exceptional circumstances, but I've seen installations where it's running with the stuff and yet cable appear and test fine, I have never once seen PVC insulation falling off in association with green goo. I think your apocalyptic prediction of fire and brimstone if it's not tackled immediately is a tad far fetched.

Almost every time I've come across this, at least some of the inner insulation has gone brittle. That tells me that, being as I don't have X-Ray vision, I have to assume that more insulation may be brittle elsewhere in the cable; it's just not worth the risk.

 

[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.