Advice On Rewire Of Lighting Circuit

[Master Mech]

I have just had some work carried our to rewire a lighting circuit in my house due to it having no earthing.

The lighting circuit is the original lighting circuit that was installed when the house was built in the 50's which was ran in steel conduit.

We now want to fit metal accessories but obviously require earthing for this to be safe so a rewire of this circuit is required & to be honest has been way overdue for replacement anyway.

Like most people I did not fancy chasing all the walls out to install new cables so asked the electrician if the steel conduit already plastered into the walls could be used saving the need to chase the walls out & redecoration.

He said that would not be an issue after looking over the installation as there would be enough room for the new cabling to be fed down the old conduit which was great news.

When he came to install the new cabling here found that he could not install the twin & earth cabling with the sheath attached as there was not enough room inside the conduit.

His solution was to strip the sheath from the twin & earth cabling and then wrap all the individual wires together in electrical insulation tape.

Removing the sheath created the room required to be able to feed the cables down the existing conduit.

Where the conduit ends in the loft space he left the sheath on the cables & the ran them to a junction box.

Here are some pictures of the junction box in the loft space & the tops of where the conduit for the switch drops end.

The same lighting circuit also covers not only the upstairs bedrooms but the landing, hallway & dining room lighting so cables needed to be ran under the landing floor boards & junction boxes installed.

Here are some pictures of the junction boxes under the landing floorboards.

So my question is are there any issues with how this work has been carried out?

I am probably making a mountain out of a mole hill but I would really appreciate your input.

Many thanks

Adam

 

[Micktw68]

Thats pretty poor. Unsheathed inner cores of the T&E cabling is likely to be damaged on the sharp edges of the conduit, the containment and joint boxes is terrible .
a better solution if you wanted to avoid chasing/redecoration would have been the use of Quinetic wireless switches.

 

[Pete999]

Thats pretty poor. Unsheathed inner cores of the T&E cabling is likely to be damaged on the sharp edges of the conduit, the containment and joint boxes is terrible .
a better solution if you wanted to avoid chasing/redecoration would have been the use of Quinetic wireless switches.

Very poor workmanship striping all the mech protection off of the twin cable is very poor the inner cores of the twin, and earth are not designed to be used this way, not a very knowledgeable Electrician, nor is it compliant with the Regulations ( BS7671) PS Did you receive any certification from this so called Electrician? an EIC,

 

[James]

It’s not a good job, there are ways that it could have been done better.

I suspect that the original wiring was 1mm and they have used 1.5mm because it was what they had in the van.


Stripping back twin and earth to feed down conduit is not an installation method I would be happy to use.

 

[Dustydazzler]

On a fall rewire i would have expected the metal split tube ideally be removed and a new back box + plastic conduit be installed for the new cables.
As for all the random junction boxes , it’s not a bad job but again on a full rewire I would have preferred to have the connections at the switch.

 

[Mike Johnson]

Very poor workmanship striping all the mech protection off of the twin cable is very poor the inner cores of the twin, and earth are not designed to be used this way, not a very knowledgeable Electrician, nor is it compliant with the Regulations ( BS7671) PS Did you receive any certification from this so called Electrician? an EIC,

Genuine question, are the inner cores of T&E different to single cores?
Can you also point out which Regulation it contravenes?

Must admit I wonder if using single cores of 1mm would have solved the problem if indeed they did use 1.5mm, difficult to see.

I would also like to see the EIC especially the CPC resistance/insulation values.

 

[Wilko]

It’s good that Wago connectors have been used, but none of those junction boxes are suitable to be placed in the building fabric. For reference Regulation 526.3 applies. If I’ve understood correctly how these junction boxes are to be placed (in walls and under floors) then for me this work is non compliant. As well as messy.

 

[Baddegg]

Can’t see the point in using wagos without the enclosures?....Not sure if it is against regs but not something I’d have done with regards the switch drops conduit.....

 

[James]

Genuine question, are the inner cores of T&E different to single cores?
Can you also point out which Regulation it contravenes?

Must admit I wonder if using single cores of 1mm would have solved the problem if indeed they did use 1.5mm, difficult to see.

I would also like to see the EIC especially the CPC resistance/insulation values.

Inner cores of T+E are not designed to give any significant mechanical protection (this is dealt with by the outer sheaf)

The cover on single cores is thicker and often a harder grade of pvc.
Also, it has been tested and certified for installation and use in conduit, including resisting damage caused by pulling down conduits.

 

[Master Mech]

Very poor workmanship striping all the mech protection off of the twin cable is very poor the inner cores of the twin, and earth are not designed to be used this way, not a very knowledgeable Electrician, nor is it compliant with the Regulations ( BS7671) PS Did you receive any certification from this so called Electrician? an EIC,

He finished the job Friday & says I will receive the certificate in around two weeks. I did say I thought that was a long time to wait & he said he has 30 days to issue the certificate & is very busy hence the delay.

It’s not a good job, there are ways that it could have been done better.

I suspect that the original wiring was 1mm and they have used 1.5mm because it was what they had in the van.


Stripping back twin and earth to feed down conduit is not an installation method I would be happy to use.

I am pretty sure he used 1.0mm as this is what was written on the sheath stripped off the cables I cleaned out of all the loft insulation.

Does using stripped T&E in conduit contravene the wiring regulations? If so this gives me something else to go back to him with.

It’s good that Wago connectors have been used, but none of those junction boxes are suitable to be placed in the building fabric. For reference Regulation 526.3 applies. If I’ve understood correctly how these junction boxes are to be placed (in walls and under floors) then for me this work is non compliant. As well as messy.

Would the appropriate Wagobox for the connector type solve the junction box issue?

Now I know about these Quinetic wireless switches that obviously would have been an option. Is there any other solutions that do not involve chasing the walls out that comply with the regulations?

 

[Mike Johnson]

Inner cores of T+E are not designed to give any significant mechanical protection (this is dealt with by the outer sheaf)

The cover on single cores is thicker and often a harder grade of pvc.
Also, it has been tested and certified for installation and use in conduit, including resisting damage caused by pulling down conduits.

Surely both types of cable have to meet the Thermoplastic criteria of withstanding 70deg C, in which case I can't see the manufacturer using a different grade of pvc on T&E, I think I will follow this up with Doncaster cables and see what they say.

 

[westward10]

If I was asked can I use the existing conduits I would find out first before committing. You can strip the outer sheath away however I would argue it should be correctly contained and I am not convinced an open ended conduit drop achieves this.
For a rewired circuit you avoid junction boxes at all costs whether they are maintenance free or not, in this case he has employed them no matter what the cost.

 

[Pete999]

Genuine question, are the inner cores of T&E different to single cores?
Can you also point out which Regulation it contravenes?

Must admit I wonder if using single cores of 1mm would have solved the problem if indeed they did use 1.5mm, difficult to see.

I would also like to see the EIC especially the CPC resistance/insulation values.

Can't tell you the reg no as I don't have a copy handy.
If you look at the BS number for single core cables used in conduit systems, they are different from TandE, plus the inner cores of T and E are what they are insulated inner cores and not designed for the purpose described in the OP.

 

[Pete999]

Surely both types of cable have to meet the Thermoplastic criteria of withstanding 70deg C, in which case I can't see the manufacturer using a different grade of pvc on T&E, I think I will follow this up with Doncaster cables and see what they say.

Don't think there is any difference in the PVC, it's the construction that counts, usage should be the criteria here horses for courses as the saying goes, you wouldn't use single cables to wire you're house unless they were designed for that purpose, and totally enclosed with conduit or trunking, would you????
Please let the forum know what Doncaster say, it will be interesting, plus why do they manufacture TandE the way they do with an outer sheath of Mech protection?

 

[Vortigern]

Thanks guys, that was one of my jobs. Anyway such a device (metal containment) for singles/T&E should technically be earthed which it is not. As @Wilko points out the JBs should be MF so replacing them with wago MF boxes would sort that. In order to stop thermal cycling and vibration causing any harm the JB should be affixed to the joists which Wago boxes have provision for so that would meet that criteria. I normally sleeve the three core as well. Essentially I see nothing too bad here, it could be improved but I do wonder why the OP does/did not have enough confidence in the spark in question to not go around after him and check his work. Any comments OP? I have once or twice been held to account by customers questioning methods of installation which comply with regs and it can be very difficult for the installer where there is no merit in such a lack of confidence. However there is some merit in the OP, in this case, but clearly the installation has been left a lot safer than when he started looking on the bright side.

 

[westward10]

PVC T&E and PVC singles are both manufactured to BS6004 and it would be assumed the insulation of the copper conductor is of an equivalent. If the sheath of the T&E is removed then it should be correctly contained as with singles after all the sheath is removed at accessories and within distribution boards.

 

[HappyHippyDad]

I agree that on a rewire junction boxes should be avoided, but sometimes we do use them when it's going to make live MUCH easier. That surface box is an odd choice but if it is in the loft then they do not need to be maintenance free, I have seen far far worse, at least there is no basic insulation showing and he has cable tied them to keep in place.

I cant comment on twin and earth being stripped back and put in metal conduit as I don't know if it's any different to singles, although from James's post it looks like it is. The metal conduit will certainly give greater protection than a piece of plastic. I don't like the sharp edges on it though, some heat shrink would have been better along with something to soften those edges. Plus it needs to be earthed, but perhaps it is.

 

[Master Mech]

The consumer unit is under the stairs & original lighting circuit comes out of the top of the consumer unit into the cavity inside the stairs making its way to under the floorboards of the landing.

All the cables going to & from the consumer unit are plastered into the wall & if I can avoid it I asked if it was possible to not chase the wall out. As you can tell I am not a fan of decorating

The solution he came up with was to drill a hole through the wall the consumer unit is mounted on which is an external wall & run a cable from the consumer unit in conduit on the outside of the house up to the loft.

From there he has split that feed in the loft for all the lights in the three bedrooms upstairs.

To be able to rewire the landing, hallway & dining room lights he used the switch drop for the landing light that also drops all the way under the landing floorboards. Then placed junction boxes under the landing floor boards to be able to supply the dining room & hallway lights.

I hope this all makes sense.

Thanks guys, that was one of my jobs. Anyway such a device (metal containment) for singles/T&E should technically be earthed which it is not. As @Wilko points out the JBs should be MF so replacing them with wago MF boxes would sort that. In order to stop thermal cycling and vibration causing any harm the JB should be affixed to the joists which Wago boxes have provision for so that would meet that criteria. I normally sleeve the three core as well. Essentially I see nothing too bad here, it could be improved but I do wonder why the OP does/did not have enough confidence in the spark in question to not go around after him and check his work. Any comments OP? I have once or twice been held to account by customers questioning methods of installation which comply with regs and it can be very difficult for the installer where there is no merit in such a lack of confidence. However there is some merit in the OP, in this case, but clearly the installation has been left a lot safer than when he started looking on the bright side.

I did question the electrician about some other work he carried out which did not end very well. He got very offended that I was questioning his work & that I did not trust him. He took it very personally.

I have another thread here about a radial he installed along with this circuit & when I asked him why he installed a 32 amp MCB on a 4mm2 cable that he ran in conduit with other cables he said it was fine & posed no risk.

I told him it did not meet the wiring regulations but apparently he has never had an issue in his years of experience & they were only guidelines.

 

[Master Mech]

Plus it needs to be earthed, but perhaps it is.

What's the best way to know if it's earthed?

Right now its just a piece of metal conduit plastered into the wall. It is not connected to the back box it drops to or anything on the other end in the loft.

 

[Pete999]

Thanks guys, that was one of my jobs. Anyway such a device (metal containment) for singles/T&E should technically be earthed which it is not. As @Wilko points out the JBs should be MF so replacing them with wago MF boxes would sort that. In order to stop thermal cycling and vibration causing any harm the JB should be affixed to the joists which Wago boxes have provision for so that would meet that criteria. I normally sleeve the three core as well. Essentially I see nothing too bad here, it could be improved but I do wonder why the OP does/did not have enough confidence in the spark in question to not go around after him and check his work. Any comments OP? I have once or twice been held to account by customers questioning methods of installation which comply with regs and it can be very difficult for the installer where there is no merit in such a lack of confidence. However there is some merit in the OP, in this case, but clearly the installation has been left a lot safer than when he started looking on the bright side.

"you see nothing to bad" what? stripping twin and earth and threading the cores down a conduit is not bad? it's downright disgraceful workmanship.

 

[James]

PVC T&E and PVC singles are both manufactured to BS6004 and it would be assumed the insulation of the copper conductor is of an equivalent. If the sheath of the T&E is removed then it should be correctly contained as with singles after all the sheath is removed at accessories and within distribution boards.

They both meet the requirements of BS6004, for abrasion resistance tests, they are tested as a complete product, inner cores are suitable for being contained within an enclosure.
However there is no testing or approval for taking a cable apart and drawing its unprotected inner cores through conduit.

 

[Vortigern]

I don't see it Pete, singles are drawn through conduit all the time what is different in this case. While I understand you feel it is disgraceful, and maybe you are right, what is wrong with it? How does it not comply or present a danger to the client? What reg would you quote in an EICR for instance. I eschew going in too hard on another electrician especially in a public place. I always feel the other side should be present to defend themselves. Besides which it is tantamount to libellous in describing work in such a way and may have no defence where it cannot be proven.

 

[7029 dave]

Well for starters 1mm t&e should have been used, also why 2 cables down could of used 1mm 3 core and earth.

 

[westward10]

Whether he should have stripped the cables back is debatable, what isn't debatable is that once he realised he could not get the cables down the tubes was to stop and review the situation. As previously stated this would have been my first port of call to see if it was feasible. Conductors are clearly exposed outside of the tube and wrapped with tape, this is not acceptable.

 

[Wilko]

As @Wilko points out the JBs should be MF so replacing them with wago MF boxes would sort that.

The connector 2273 seems to have been popular and it will need an adapter for the standard Maintenance Free box (I don’t use these connectors for that reason ).

 

[westward10]

I suppose the most not obvious solution as it isn't used too much now was to use 6181Y they would have flown down the tube.

 

[Pete999]

I don't see it Pete, singles are drawn through conduit all the time what is different in this case. While I understand you feel it is disgraceful, and maybe you are right, what is wrong with it? How does it not comply or present a danger to the client? What reg would you quote in an EICR for instance. I eschew going in too hard on another electrician especially in a public place. I always feel the other side should be present to defend themselves. Besides which it is tantamount to libellous in describing work in such a way and may have no defence where it cannot be proven.

Simple really mate, whilst I can't point you to any hard and fast written regulations, the simple facts are the cores of a multi core cable are not designed to be use without the Mechanical protection provided by the outer sheathing,
Singles designed for installing in conduit or trunking are and are installed as such , I agree that twin and earth is stripped down to the individual cores are visible in switches etc, but that is an enclosure in it's own right, it's the same as saying I can't get this twin and earth through this hole, "I know Ill strip the sheathing off it will fit then.
I stand by what I said earlier the OP described the install in his house is disgraceful.

 

[ferg]

It looks a bit rushed / rough and there are undoubtedly bits that could and should have been done differently.

However I'd be struggling to justify paying someone else to rip it out and re-do it. I think that is a reasonable threshold for the difference between a bit rough and downright dangerous.

 

[Mike Johnson]

Well this has certainly polarised opinions, will be interesting when and if Doncaster cables get back to me.

 

[Dustydazzler]

I certainly wouldn’t advocate pulling it all out n starting agai.
I rewired my parents house 20 years ago using the original split tube , but managed to get a twin n earth all the way down it fully sheathed all the way.
if I couldn’t get it down the tube sheathed I would have chopped it out & put some 20mm pvc conduit instead. But that’s just me ...

 

[Master Mech]

Well for starters 1mm t&e should have been used, also why 2 cables down could of used 1mm 3 core and earth.

The drop that has the three core with the twin & earth cable feeds two switches. A 2 gang switch & 1 gang switch.

When the house was built they decided to use one drop for both rooms.

The only insulation the CPC's have is the electrical tape that is holding all the wires together.

 

[Pretty Mouth]

It seems to me that the problems with this install are a result of the spark trying to keep the OP happy, by avoiding damage to the decor. Had he been able to cut in chases and new boxes, there would have been no need for the junctions in the building voids, or for stripping the sheath from the T+E.

 

[7029 dave]

The drop that has the three core with the twin & earth cable feeds two switches. A 2 gang switch & 1 gang switch.

When the house was built they decided to use one drop for both rooms.

The only insulation the CPC's have is the electrical tape that is holding all the wires together.

The drop that has the three core with the twin & earth cable feeds two switches. A 2 gang switch & 1 gang switch.

When the house was built they decided to use one drop for both rooms.

The only insulation the CPC's have is the electrical tape that is holding all the wires together.

Okay understand that, 1.5mm cable was a bad choice, 1mm cable's might have gone down together with a bit of lubricate such as fairy liquid thats what I have used, failing that chase out the other switch drop, or surface mini trunking.

 

[Dustydazzler]

It seems to me that the problems with this install are a result of the spark trying to keep the OP happy, by avoiding damage to the decor. Had he been able to cut in chases and new boxes, there would have been no need for the junctions in the building voids, or for stripping the sheath from the T+E.

quentic switches would have been the best option

 

[westward10]

6181Y.

 

[7029 dave]

quentic switches would have been the best option

Forgot about them, see new products old sweats like me forget.

 

[Pretty Mouth]

quentic switches would have been the best option

I think the OP had metal accessories in mind. Do quinetic do modules to fit? Would be a good workaround if so

 

[Vortigern]

I would recommend quinetic in that situation but the cost can be offputting.

 

[Vortigern]

6181Y.

don't think you could have got all those down there though, same situation as a three core and earth with two core and earth.

 

[westward10]

don't think you could have got all those down there though, same situation as a three core and earth with two core and earth.

They would fly down?

 

[Master Mech]

Okay understand that, 1.5mm cable was a bad choice, 1mm cable's might have gone down together with a bit of lubricate such as fairy liquid thats what I have used, failing that chase out the other switch drop, or surface mini trunking.

Apologies if I am getting the wrong end of the stick but when you say 1.5mm cable was a bad choice you are saying that 1.5mm2 cable was used?

I can 100% confirm that all the cables used were 1.0mm2 both the three core & the twin & earth.

What seems to have happened back in the 50's when the conduit was installed they had the fantastic idea to flatten/crush the conduit a little that was plastered into the wall so it is more oval than round.

I can only guess but it seems they did this to avoid having to chase the walls out as much.

Even when using 1.0mm2 cable there was no way a three core with twin & earth way going to fit down that conduit with the sheath. He did try with fairy liquid as he asked me for my help to try & pull them through with him.

 

[Intoelectrics]

Personally I would have done things differently, my main concern would be at the entry to the split metal conduit. But I'm not going to jump on the electrician who did this work when we only have one side of the story.
No offense to the OP but we are not privy to what you agreed, cost, limitations, timeframes... It only appears to me that the electrician was trying to save you the headache of redecorating. Maybe there were alternative solutions to overcome this, difficult to say without actually surveying the job ourselves.

To the OP,
have you invited the electrician back to comment/fix any of the things you have pointed out to us?

 

[Intoelectrics]

Even when using 1.0mm2 cable there was no way a three core with twin & earth way going to fit down that conduit with the sheath. He did try with fairy liquid as he asked me for my help to try & pull them through with him.

So at this point did the electrician not suggest an alternative? Since you were witness to the fact that the cables could not be pulled down the conduit, you knew that there was a problem?

 

[Master Mech]

Personally I would have done things differently, my main concern would be at the entry to the split metal conduit. But I'm not going to jump on the electrician who did this work when we only have one side of the story.
No offense to the OP but we are not privy to what you agreed, cost, limitations, timeframes... It only appears to me that the electrician was trying to save you the headache of redecorating. Maybe there were alternative solutions to overcome this, difficult to say without actually surveying the job ourselves.

To the OP,
have you invited the electrician back to comment/fix any of the things you have pointed out to us?

I have him coming back to change the 32 amp MCB on the radial he fitted for a 20 amp MCB.

Like I said in another post when I brought up the above issue he was not a happy chappy so I would imagine it will be the same for the issues discussed in this thread.

I will talk to him about the issues people have brought to my attention in this thread which was the whole point of me creating this thread.

I am an automotive tech & when I looked over the work I saw a few things I was not happy with but this is not my industry so I have not clue if this work was acceptable or not so thought I would ask here to get advice from the people that do before approaching him.

 

[telectrix]

my first thought would ave been to install just 4.0mm single earth cables assuming that the existing twin cable was OK for continued use.

 

[Master Mech]

So at this point did the electrician not suggest an alternative? Since you were witness to the fact that the cables could not be pulled down the conduit, you knew that there was a problem?

Well he had a good think up in the loft & he came up with the solution we have now, the stripped cables.

I thought this was not "correct" so to speak but as I have said this is not my field so I had no way of knowing if this was acceptable or not so I was not in the position to make the call if there was a problem or not at the time.

Hence the creation of this thread, I am not trying to throw the guy under the bus I just wanted other peoples opinions on the work to see if my concerns had any merit.

 

[7029 dave]

Apologies if I am getting the wrong end of the stick but when you say 1.5mm cable was a bad choice you are saying that 1.5mm2 cable was used?

I can 100% confirm that all the cables used were 1.0mm2 both the three core & the twin & earth.

What seems to have happened back in the 50's when the conduit was installed they had the fantastic idea to flatten/crush the conduit a little that was plastered into the wall so it is more oval than round.

I can only guess but it seems they did this to avoid having to chase the walls out as much.

Even when using 1.0mm2 cable there was no way a three core with twin & earth way going to fit down that conduit with the sheath. He did try with fairy liquid as he asked me for my help to try & pull them through with him.

OK looking at the pictures the conductors/insulation do look bigger than 1mm2, but you was there not me.

 

[Master Mech]

OK looking at the pictures the conductors/insulation do look bigger than 1mm2, but you was there not me.

When I get home later I will have a close look at the cables emerging from the conduit but I am very confident they are 1.0mm2

I will let you know.

 

[Midwest]

If I recall, there were/are rubber bushes available for this situation in a rewire. Not that this helps with the amount of t&e down the split conduit.

Could the switch drop t&e cables be replaced with a suitable multi core flexible cable?

 

[Pete999]

It looks a bit rushed / rough and there are undoubtedly bits that could and should have been done differently.

However I'd be struggling to justify paying someone else to rip it out and re-do it. I think that is a reasonable threshold for the difference between a bit rough and downright dangerous.

"A bit rough" is the understatement of the year