SWA Penetration

[CWalling]

Hi guys,

looking at a small stable conversion. DNO is putting supply to a out door box away from house. So putting in switched fuse and 25mm2 SWA underground to the house, up the corner and under the gutter to where CU will be inside. What’s the best way to bring the SWA into the house? Drill straight through and use sealant? Wiska box on the outside big enough to take 2 Henley blocks and an earth terminal and take standard tails into the house? Not seen any examples on a purely wooden structure before.

cheers in advance

 

[cliffed]

Swa into the house maybe the best idea would terminate in adaptable box, leave the sheath on the cables on route to your DB.
The problem with Swa is that it’s bulky & bending it can be a problem drilling @ an angle towards the outside helps.

 

[James]

Have you considered using a standard meter box on outside of house to terminate the swa into an isolator?

it is nice to have a means of isolation that is easy to identify for emergency services or other trades that may need to turn off the power without having to ask where to do so.

I would avoid terminating a large swa into a plastic box, eventually it will bend or crack and let in water.

 

[CWalling]

Sorry, should have mentioned I’m terminating into a double pole switch before the CU, as you say for ease of isolation. The client doesn’t want a meter box on the house, DNO could of put cable to a meter box that would have been within 3m of the CU if it they would have one the house.
I’m thinking my best bet is terminating the SWA in a wiska box with Henleys in it so I can bring standard tails in, that way I can keep double insulation when I get to the isolator.

cheers

 

[James]

I would avoid terminating a large swa cable into a plastic box.
some careful routing should allow you to terminate swa directly into a suitable isolator.
pick a good size metal one with plenty of space to deal with cable management.

 

[mattg4321]

Sorry, should have mentioned I’m terminating into a double pole switch before the CU, as you say for ease of isolation. The client doesn’t want a meter box on the house, DNO could of put cable to a meter box that would have been within 3m of the CU if it they would have one the house.
I’m thinking my best bet is terminating the SWA in a wiska box with Henleys in it so I can bring standard tails in, that way I can keep double insulation when I get to the isolator.

cheers

Sounds like a bad idea to me.

Can you bring the swa inside a few feet below the consumer unit so you can gland into that directly?

 

[telectrix]

drill from CU straight out. decent size box over hole.SWA glanded into box but tails left long enough to terminate in CU. tube in hole to pass cable through wall (containment). add fly lead to earth armour.

 

[CWalling]

drill from CU straight out. decent size box over hole.SWA glanded into box but tails left long enough to terminate in CU. tube in hole to pass cable through wall (containment). add fly lead to earth armour.

this is where the problem lies. I’m coming to an isolator before CU so need double insulation to the isolator. I suppose I could do as telectrix says but could come straight to the isolator in 25mm conduit if I use one of the metal enclosure style isolators. Would have enough room for SWA flylead too.

 

[telectrix]

why not fit isolator inside house, adjacent to house CU, then from isolator out in conduit/tube as per mylast post.

 

[CWalling]

why not fit isolator inside house, adjacent to house CU, then from isolator out in conduit/tube as per mylast post.

Yea sorry, this is what I meant. I havnt got the best English skills

thanks for all the help

 

[CWalling]

Hi Guys,
Revisiting this as it has changed. The client has now extended the outside wall to come down with the overhang.
There is now a ‘gutter’ in the floor was used to take away rainwater off the floor outside the stable, it’s about 50-60mm deep and runs from one end of the house to the other.
It would make this job a lot easier to bring the SWA through this in some ducting (possible workshop and outside socket/light supply to run outside too).
I’ve asked other electricians this question and it’s literally 50/50, do I need to put an RCD up stream if I’m running through the floor and up the wall? Does this count as the fabric of the house as it would with normal tails? I was always taught that the SWA negated the need for an RCD upstream?
Sorry for the revisit, I mainly deal with industrial electrics, if you want pictures then I’ll be at the job this evening so I can take some and post it.

cheers

 

[DefyG]

Not necessarily,, depending upon earthing arrangement (eg TT)!

was always taught that the SWA negated the need for an RCD upstream?

 

[telectrix]

SWA does not requre upstream RCD unless it's TT and you need the RCD for fault protection.