New Extension & Board

[daver]

Sat in a boring conference and some time on my hands, but dont have any reference material to hand. So a bit of help please.

Been asked to price an extension, which is bigger than the original house.

Could come from original board in hallway, go up and across and then down for the following circuits

Kitchen Ring
Cooker
Living room radial
Bedroom Radial
Lighting on both floors
Smokes

But my thinking is, henley block go under floorboards with SWA out to extension to a new board. Length approximately 6 - 7M.

All that will be left then on original board will be 2 rings and a lighting circuit.

No electric shower.

Could one of you kindly see how this calculates out and what size cable is needed to the new board.
Will clip direct, but any factors for through wall and in footings for 6 inches. Will feed through plastic pipe for this.

Cheers in advance.

Dave

 

[stephenf8542]

wouldn't your henley block be classed same as a junction box and have to be accessable?

 

[TPES]

But my thinking is, henley block go under floorboards with SWA out to extension to a new board.

Cheers in advance.

Dave

Maybe a daft question but how do you terminate SWA into a henley block, or have a read it wrong ?

Sounds like a **** hot plan though, I'd go with that.

 

[Spudnik]

I dont see why cant use 25mm tail set cliped and safe plated across joists.

Sorry, but im not sure i would do that.

If the SWA is fairly easy to install to the new CU point then use that.

 

[acat]

I agree with Jason, junction box, henley block henley block or whatever I would avoid where possible, a continuious run of cable is always best.



Chris

 

[daver]

Think I am put on this planet to cause confusion.

All original gear is in hall in a cupboard (C/U - Fuse etc). My option is to go up with all the new circuits, then across into new extension and then down and up for the new circuits. That would all be of that consumer unit.

Or

Split tails (Henley block), then adaptable box to SWA. Go down then run under floor boards (2.5 foot clearance) for 6M, through outside wall and up to new consumer unit in extension. Then all new circuits of this.

I only really needed to know cable size as I have no reference material with me at the moment.

Cheers

 

[Spudnik]

I would split tails into henly, 80A switch fuse and 25mm SWA to new cu position.

If you dont know the load then max it.

 

[daver]

I would split tails into henly, 80A switch fuse and 25mm SWA to new cu position.

If you dont know the load then max it.

Hi Jason, sorry to jump back to an old post but going to do as you suggested above.
Going to do this in 16mm T&E with additional 10mm CPC to new C/U. No problem under floor as there is 1M clearance, but up wall in new extension will be less than 50mm.

Can you link me to an 80A switched fuse with RCD protection. Just trying to quote and cant find one that is enclosed.

Cheers

Dave

 

[ajelec10]

Just a thought, But if you use phase blocks you will need to provide one main switch for the installation before it splits.
Regards
AJ

 

[Doomed]

WYLEX 80A 30mA DP RCD - Screwfix.com, Where the Trade Buys the enclosures are seperate but listed with the RCD

 

[Spudnik]

Hi Jason, sorry to jump back to an old post but going to do as you suggested above.
Going to do this in 16mm T&E with additional 10mm CPC to new C/U. No problem under floor as there is 1M clearance, but up wall in new extension will be less than 50mm.

Can you link me to an 80A switched fuse with RCD protection. Just trying to quote and cant find one that is enclosed.

Cheers

Dave

This is where its going to be a problem.

You cannot put a 30mA RCD upfront of the CU.

Im afraid you are either going to have to run it surface, get it deeper than 50mm, or use a suitably mechanically protected cable (SWA).

 

[daver]

This is where its going to be a problem.

You cannot put a 30mA RCD upfront of the CU.

Im afraid you are either going to have to run it surface, get it deeper than 50mm, or use a suitably mechanically protected cable (SWA).

Hi Jason and thanks again. This is only my second job, so be gentle.
I'm a little confused, because on my assesment, the job I took him to was 1 large house with 8 flats. The first question he asked was how I had done the sub mains to each flat. It was run in 16mm T&E with an additional 10mm cpc. His quote was, that if the 16mm was less than 50mm deep, then I would have to change my 60947 80A fused Isolators to RCD's. As it is, all the sub mains are around 150mm deep and boxed so no problem there.

So I was carrying this principal forward to this extension. I can just run new circuits up from existing board, accross and then down and up. But it would probably be easier and less disruptive to put sub main to extension and work out of a new DB.

Is this the issue of a circuit tripping the RCD, which will take out the sub main RCD and the whole extension.

Does metal capping constitute adequate protection or should I whiz out a couple of bricks on outside wall and put sub main in cavity.

Sorry for repeating and being a pain, your help is very much appreciated.

Dave

 

[not clever]

What is the rating of the suppliers cut out fuse? .... 100A? then you cant use the 16mm.
If you are wanting to use 16mm I'd go

1) split tails
2) install single point of isolation by 100a DP switch
3) extension sub on a 60/80a switch fuse
4) My preference would be swa so no rcd required on a TN over 32a or distribution circuit.
4a) if using 16mm T/E make sure it's dropped into some earthed trunk/tube where not below 50mm.
5) extension cu either use dual rcd board or rcbo each circuit.


Metal capping doesn't constitute adequate earthed metal protection

 

[daver]

What is the rating of the suppliers cut out fuse? .... 100A? then you cant use the 16mm.
If you are wanting to use 16mm I'd go

1) split tails
2) install single point of isolation by 100a DP switch
3) extension sub on a 60/80a switch fuse
4) My preference would be swa so no rcd required on a TN over 32a or distribution circuit.
4a) if using 16mm T/E make sure it's dropped into some earthed trunk/tube where not below 50mm.
5) extension cu either use dual rcd board or rcbo each circuit.


Metal capping doesn't constitute adequate earthed metal protection

Just out of interest, from your 80A Switch fuse, how would you connect to your SWA. Adaptable Box ?? Just want to be neat without to much clutter and with the T&E I can go straight in.

Still learning

Thanks

 

[ROBERTEBBUTT]

kmf for over 3m run?