Meter tails in cavity

[mattg4321]

Ok own up who's done this?

I try my hardest to never do this but have, on very rare occasion installed meter tails in a cavity as the lesser of evils.

Would be interesting to hear real world thoughts on this and potential work arounds so you don't have to. I know someone on here posted a while back about some sort of capping that you could put over the tails so they couldn't be drilled. Not entirely convinced about that although I've not had a proper look at it in real life.

I had one recently where the meter box was on external wall and I needed to run an armoured from there to an internal consumer unit. Went to great trouble to avoid running the cable in the cavity and builder comes along and says why didn't you just push it up the cavity!

 

[Dillb]

Whats your issue with running cables in a cavity?

 

[Midwest]

Can't see how it can be avoided?

My only issue with it, you can't see whats happening to the cable as its being installed, and unsupported over the distance.

 

[Dillb]

Can't see how it can be avoided?

My only issue with it, you can't see whats happening to the cable as its being installed, and unsupported over the distance.

While I agree you cant see whats happening, then end you pull out should give you a idea that its not being damaged. As for supporting of it, its only the same as cables in vertical trunking, which dont get supported.

 

[mattg4321]

Whats your issue with running cables in a cavity?

UKPN don't like it and building inspectors often don't like it as you're bridging the cavity. Although quite what the insulation filling the cavity is doing if not bridging the cavity is anyones guess.

 

[Midwest]

While I agree you cant see whats happening, then end you pull out should give you a idea that its not being damaged. As for supporting of it, its only the same as cables in vertical trunking, which dont get supported.

The cable is made up of its entire length, whats happening at its ends, doesn't necessarily suggest what has happened to the rest of it.

I though vertical trunking was required to have cable supports over certain lengths; was there some new reg or update on that in the last amendment.

 

[Midwest]

UKPN don't like it and building inspectors often don't like it as you're bridging the cavity. Although quite what the insulation filling the cavity is doing if not bridging the cavity is anyones guess.

Thing is though, if the meter box is on the outside and CU on the inside, it has got to go in the cavity some point, even straight through will bridge the cavity.

 

[Dillb]

The cable is made up of its entire length, whats happening at its ends, doesn't necessarily suggest what has happened to the rest of it.

Well thats it, we cant run a cable through any wall at all then if thats the case, unless we completly dismantle it then rebuild it once the cables installed.

 

[Wes1000]

I think you are thinking of this.
External Cable Protectors - https://www.directchannel.uk.com/gs9-tail-cable-protectors
A lot thicker than capping and you’d have to really try to be able to hammer or drill through it.
Like you say matg4321 I’m sure it has been mentioned here before.

 

[Leesparkykent]

PRODUCTS | TridentSections - http://www.tridentsections.co.uk/press/products/

My wholesaler orders it from here.

 

[Midwest]

Well thats it, we cant run a cable through any wall at all then if thats the case, unless we completly dismantle it then rebuild it once the cables installed.

Thing is though, if the meter box is on the outside and CU on the inside, it has got to go in the cavity some point, even straight through will bridge the cavity.

Now your just being silly. I have and will install such cables in a cavity, but you have to bear these points in mind.

 

[Dillb]

Now your just being silly. I have and will install such cables in a cavity, but you have to bear these points in mind.

Thats exactly my point, use your professional judgement as to weather any damge to the cable is occuring.

 

[Midwest]

Thats exactly my point, use your professional judgement as to weather any damge to the cable is occuring.

The potential damage to the cable, is a bit of a shot in the dark though (if you excuse the pun).

 

[telectrix]

Thats exactly my point, use your professional judgement as to weather any damge to the cable is occuring.

what's the weather got to do with it?

 

[Octopus]

All this worry about bridging the gap ... yet they fill up the “cavity” with insulation, after the builders have filled up the bottom with carp ...

 

[Spoon]

Isn't the issue with bridging the gap so that water doesn't transfer from the outside wall to the inside wall?
You can stop this by installing the cable at an angle, so the water can't run down the cable to the inside wall. This is of course for installing the cable virtually horizontal.

 

[Midwest]

Think its the suggestion of such cable running vertically in the cavity, that allegedly can cause water breaching the cavity.

 

[HandySparks]

If the cavity is subsequently filled with insulation, the current carrying capacity of the cables will be significantly reduced.

 

[Dillb]

If the cavity is subsequently filled with insulation, the current carrying capacity of the cables will be significantly reduced.

Thats like wiring a conservatory and putting sockets on the wall attached to the house, they will need to be IP rated incase they ever take the conservatory down.

You can only allow for what is there when installing.

 

[Deleted member 26818]

Thats like wiring a conservatory and putting sockets on the wall attached to the house, they will need to be IP rated incase they ever take the conservatory down.

You can only allow for what is there when installing.

When working on the O2, we installed IP rated containment and accessories, just in case they ever removed the cover.
The fact that the internal structures are made from MDF not withstanding.

 

[Des 56]

Put the cables in the cavity,tell no one you did so
Any officious council employee will be none the wiser

He will have the exact measure of wisdom whether he knows or not (regarding cables in cavities)
The measure of his wisdom means he would have no clue of what should be done if he objected in the first place

 

[Spoon]

I though vertical trunking was required to have cable supports over certain lengths; was there some new reg or update on that in the last amendment.

Just been looking for this, cause I was curious.
We have:

522.8.4 Where conductors or cables are not supported continuously due to the method of installation, they shall be supported by suitable means at appropriate intervals in such a manner that the conductors or cables do not suffer damage by their own weight.


522.8.5 Every cable or conductor shall be supported in such a way that it is not exposed to undue mechanical strain and so that there is no appreciable mechanical strain on the terminations of the conductors, account being taken of mechanical strain imposed by the supported weight of the cable or conductor itself.

Neither of these state a measurement. The only one that does is regards to caravans..

721.522.8.1.3 All cables, unless enclosed in rigid conduit, and all flexible conduit shall be supported at intervals not exceeding 0.4 m for vertical runs and 0.25 m for horizontal runs.

 

[HandySparks]

Thats like wiring a conservatory and putting sockets on the wall attached to the house, they will need to be IP rated incase they ever take the conservatory down.

You can only allow for what is there when installing.

Not really a fair analogy. If you demolish a conservatory, you'll want to remove the sockets and wiring with it. Cavity wall installation is a popular home improvement, ie not unusual. The installers may well be unaware of the cables in the cavity and are unlikely to do anything about it if they are.

 

[telectrix]

The installers may well be unaware of the cables in the cavity and are unlikely to do anything about it if they are.

they wouldn't give a sh*t anyway. bung it in as quick as possible, move on. sod any other trades being compromised.

 

[DPG]

Never a fan of cables in cavities. They will bridge the cavity in multiple locations - this can cause problems and is frowned upon. Traditional wall ties also bridge the gap, but they are designed so that any moisture is dropped down the cavity rather than tracking across.

And, as someone alluded to earlier, how do you support horizontal runs of cable in the cavity? It could be going through for several meters without any support other than where it is sat against the edge of a brick at either end.

And thirdly the issue of all that wall insulation being added at some point to nicely downrate the cable.

Just generally not a good thing to do.

 

[Spoon]

And, as someone alluded to earlier, how do you support horizontal runs of cable in the cavity? It could be going through for several meters without any support other than where it is sat against the edge of a brick at either end.

Just out of curiosity, what do you guys do then you put cable in the oval trunking like below?

What max length do you use.
As you see by my earlier post. There is no actual length specified in the regs.

 

[DPG]

Doesn't matter - the tubing supports it??

 

[Dillb]

Never a fan of cables in cavities. They will bridge the cavity in multiple locations - this can cause problems and is frowned upon. Traditional wall ties also bridge the gap, but they are designed so that any moisture is dropped down the cavity rather than tracking across.

And, as someone alluded to earlier, how do you support horizontal runs of cable in the cavity? It could be going through for several meters without any support other than where it is sat against the edge of a brick at either end.

And thirdly the issue of all that wall insulation being added at some point to nicely downrate the cable.

Just generally not a good thing to do.

So how do YOU pass a cable through a wall with a cavity in it?

 

[DPG]

So how do YOU pass a cable through a wall with a cavity in it?

No problem going through a cavity wall with any cable. It's long runs of cable run within the cavity I dislike.

 

[happysteve]

PRODUCTS | TridentSections - http://www.tridentsections.co.uk/press/products/

My wholesaler orders it from here.

Silly question...: how do you cut it to length?

 

[Leesparkykent]

Silly question...: how do you cut it to length?

Grinder of jigsaw.

 

[Wilko]

Just out of curiosity, what do you guys do then you put cable in the oval trunking like below?
View attachment 42847

What max length do you use.
As you see by my earlier post. There is no actual length specified in the regs.

Hi - well, it's just used for drops from ceiling, so typically less than 3m, and there never seems to be any issues.
Just for some fun (still sick today ) - I did see some data saying soft copper could take a static load 15N /mm2 without damage (internet source, so not sure if correct). Now 1mm twin and earth would be 3mm2, so about 4.5kg max static load. But for safety, let's assume only 1 core takes all the load and for further safety divide my internet number by 2, that's about 750gm loading, not much! But I get 1m of Prymesian's finest 1mm twin and earth to weigh in at 60gm, so 3m of it seems fine for hanging undisturbed in the conduit. Hopefully .

 

[robd]

All this worry about bridging the gap ... yet they fill up the “cavity” with insulation, after the builders have filled up the bottom with carp ...

Poor carp what have they done wrong

 

[robd]

All this worry about bridging the gap ... yet they fill up the “cavity” with insulation, after the builders have filled up the bottom with carp ...

Poor carp what have they done wrong

 

[Spoon]

Poor carp what have they done wrong

It was sooo funny I gave you a 'funny' for both posts...

 

[robd]

It was sooo funny I gave you a 'funny' for both posts...

Sorry don't know what happened there

 

[Spoon]

Sorry don't know what happened there

No worries..

 

[Andy78]

Regarding the length of unsupported vertical cables, the OSG gives guidance of no more than 5m with adequate support at the top and states this should satisfy the requirements of 522.8