Mains box to Consumer unit SWA or tails?

[grandfortune]

HI all,

usually take tails form a MEB box to consumer unit no matter what the length as long as i can get the 50mm depth, builder has told me he wants it in SWA, ive told him its pretty much impossible to terminate it right if i use SWA also i run up the cavity with the tails and there is no way i can get SWA up there so will have to run inside up the wall which i hate doing, what do you guys do if using SWA??

Cheers
Grand

 

[grandfortune]

like the look of split concentric??

 

[buzzlightyear]

is this to a flat?

 

[westward10]

like the look of split concentric??

Split concentric is no longer deemed suitable for use in walls without additional rcd protection, no idea why this is now the case.

 

[davesparks]

Split concentric is no longer deemed suitable for use in walls without additional rcd protection, no idea why this is now the case.

It is the case because it doesn't have an earthed armouring. The earth strands only surround a third of the core, the other two thirds is the neutral.

 

[grandfortune]

mmmm thats interesting, so surly tails isn't suitable then as the earth is totally separate?, SWA it is then

its a domestic house btw


how do you terminate the armored in the mains cupboard, and ---- me it will look ugly terminating it into the board.

 

[Des 56]

Could you terminate the swa into a metal box directly under where the consumer unit is mounted and connect direct ? If not can you use a adaptable box butted up to the consumer unit, gland into that with the cores straight through

 

[westward10]

It is the case because it doesn't have an earthed armouring. The earth strands only surround a third of the core, the other two thirds is the neutral.

Are you talking concentric or split concentric because I have often wondered as originally it was deemed acceptable.

 

[davesparks]

Advise the builder that if he wishes to do the electrical installation design then he will have to sign the EIC for design and accept the liability.

One method of terminating SWA in a meter box is to fit the gland to a short piece of brass angle, then heatshrink the cores with adhesive lined heatshrink to give protection and again heatshrink over the breakout.
This should give you an idea of what I mean, though in this case the bedding is stripped within the gland and the gland filled with epoxy to seal it.

 

[Dave OCD]

But if this is a new installation the board itself will be steel and you'd gland straight into it.

 

[davesparks]

Could you terminate the swa into a metal box directly under where the consumer unit is mounted and connect direct ? If not can you use a adaptable box butted up to the consumer unit, gland into that with the cores straight through

Terminate the SWA into a metal flush box behind the CU

 

[davesparks]

mmmm thats interesting, so surly tails isn't suitable then as the earth is totally separate?, SWA it is then

its a domestic house btw


how do you terminate the armored in the mains cupboard, and ---- me it will look ugly terminating it into the board.

It will only look ugly if you make it ugly.

Terminate the SWA into the flush box you fit behind the CU the same as the outgoing circuits.

 

[bigspark17]

Terminate it into a metal switch fuse isolator as you would use if the cu was >3M away.. you could float it into the back of the board without a gland if the swa was soundly cleated to provide protection of cable being dragged back & that the swa was bangod correctly supply end and a 3rd inner core was used inside the swa, it may be frowned upon & i would only do this as a last resort.

 

[Dave OCD]

Advise the builder that if he wishes to do the electrical installation design then he will have to sign the EIC for design and accept the liability.

One method of terminating SWA in a meter box is to fit the gland to a short piece of brass angle, then heatshrink the cores with adhesive lined heatshrink to give protection and again heatshrink over the breakout.
This should give you an idea of what I mean, though in this case the bedding is stripped within the gland and the gland filled with epoxy to seal it.


View attachment 37373

Ah the upside down Switchfuse is back.

 

[westward10]

Bolt an adaptable box to the back using the lid fixing screw points.

 

[davesparks]

Are you talking concentric or split concentric because I have often wondered as originally it was deemed acceptable.

I mean split concentric, the requirement for buried cables is that they have earthed armour or sheath etc. Split concentric doesn't satisfy this.

I don't know if it was ever deemed compliant for burial in a wall without RCD since that rule came in.

 

[davesparks]

Ah the upside down Switchfuse is back.

Yeah, it annoys the hell out of me, but I thought it better to have the incoming and outgoing the right way round rather than the switchfuse the right way up.

 

[davesparks]

Ah the upside down Switchfuse is back.

Yeah, it annoys the hell out of me, but I thought it better to have the incoming and outgoing the right way round rather than the switchfuse the right way up.

 

[Ian1981]

Plastic switch fuse, why not metal?
Or is this not recent?

 

[Leesparkykent]

Use 16mm twin and earth and seperate 10mm green and yellow with mechanical protection where it runs down the walls.

 

[davesparks]

Plastic switch fuse, why not metal?
Or is this not recent?

its not particularly recent, But if I was to do the job today I probably wouldn't change it for metal and would record it as a departure on the EIC.

 

[Ian1981]

its not particularly recent, But if I was to do the job today I probably wouldn't change it for metal and would record it as a departure on the EIC.

Why not metal ? You could gland straight into it
Also explain how it's a departure and not a non compliance?
It's not a consumer unit but I'd put it as a similar switch gear assembly

 

[Leesparkykent]

Personally I feel the KMF is the wrong choice for the job in the above pics due to it having to be installed upside down as the load side is at the top..I would of opted for something different or done the job differently if nothing else would fit in the cab.

 

[davesparks]

Why not metal ? You could gland straight into it
Also explain how it's a departure and not a non compliance?
It's not a consumer unit but I'd put it as a similar switch gear assembly

A departure is a non compliance, if it complied then it wouldn't be a departure.

At the time there was no suitable metal option.
Now I am still not aware of a suitable metal option, bearing in mind it is in a meter box so steel is not suitable because it will rust.
The KMF is made of a Bakelite type plastic which to the best of my knowledge is not readily combustible in the way that the soft plastic used for CUs is.
It is located outside of the building and presents no greater risk than the other plastic equipment installed in there (meter, cutout, Henley block)

 

[Ian1981]

A departure is a non compliance, if it complied then it wouldn't be a departure.

At the time there was no suitable metal option.
Now I am still not aware of a suitable metal option, bearing in mind it is in a meter box so steel is not suitable because it will rust.
The KMF is made of a Bakelite type plastic which to the best of my knowledge is not readily combustible in the way that the soft plastic used for CUs is.
It is located outside of the building and presents no greater risk than the other plastic equipment installed in there (meter, cutout, Henley block)

To depart is to install or use something that is no less safe than full compliance with bs 7671 so if bs7671 calls for non combustible enclosure on a consumer unit or similar switch gear assemblies and you don't adhere to the regulations then it's a non compliance to me and not a departure

 

[davesparks]

Personally I feel the KMF is the wrong choice for the job in the above pics due to it having to be installed upside down as the load side is at the top..I would of opted for something different or done the job differently if nothing else would fit in the cab.

It only had to be installed upside down because I'd made off the cable and fitted the KMF the right way up before I realised my mistake.
Had I paid a bit more attention it would have been done differently the KMF would be the right way up.

 

[westward10]

Why not metal ? You could gland straight into it
Also explain how it's a departure and not a non compliance?
It's not a consumer unit but I'd put it as a similar switch gear assembly

If you decide to record a departure then the level of safety should not be less than obtained by compliance with the Regulations. It can be difficult to prove such things. DSs explanation in #24 does have validity that the enclosure is more likely to char than ignite but whether its level of safety is less could be debated. The only thing I would comment on if I undertook an EICR is that it is upside down

 

[davesparks]

To depart is to install or use something that is no less safe than full compliance with bs 7671 so if bs7671 calls for non combustible enclosure on a consumer unit or similar switch gear assemblies and you don't adhere to the regulations then it's a non compliance to me.

Yes well as the designer I deem this departure to be no less safe than compliance with that particular regulation.

 

[Ian1981]

Yes well as the designer I deem this departure to be no less safe than compliance with that particular regulation.

Touché

 

[davesparks]

If you decide to record a departure then the level of safety should not be less than obtained by compliance with the Regulations. It can be difficult to prove such things. DSs explanation in #24 does have validity that the enclosure is more likely to char than ignite but whether its level of safety is less could be debated. The only thing I would comment on if I undertook an EICR is that it is upside down

I'd question it being upside down too, I wasn't very happy with that when I fitted it but I'd dug myself into a hole and had to get out of it.

This has got me wondering whether GRP would be considered non-combustible