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Topic Title: SWA into consumer unit
Topic Summary: Running through adaptable box first
Created On: 22 February 2019 07:40 PM
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 22 February 2019 07:40 PM
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Baldyhugh

Posts: 413
Joined: 01 June 2007

Evening

A job I'm in the middle of requires 25mm 3 core swa to supply a plastic IP rated consumer unit on a farm. The consumer unit doesn't lend itself very well to glanding swa so I'm going to gland it into a metal adaptable box then continue the cores unbroken through the box to terminate in the consumer unit. I'm going to use a 32mm open grommet where the cores leave the box and another 32mm grommet where they enter the consumer unit. I will then butt the adaptable box up to the consumer unit so that the two grommets are pressing against each other and the cores can pass straight through. To ease manipulating the cores through the box I plan to remove the bedding material from inside the swa right up to the gland rather than continue it through the box into the consumer unit (space is quite tight through the hole considering that I'll also be running an earth back through the hole to earth the box. As such I will have basic insulated cores passing through two grommets. The question is this, are these grommets sufficient to provide the second layer of insulation? When installed, no basic insulation will be visible as they pass through the grommets as they are both butted up to each other.

Thanks in advance
 22 February 2019 08:01 PM
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dustydazzler

Posts: 3068
Joined: 19 January 2016

Don't see a problem with this slightly unorthodox method...

Just don't forget to Earth the metal box
 22 February 2019 08:25 PM
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psychicwarrior

Posts: 683
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or ... 32mm coupler and bushes perhaps (or even just a brass bush and nut)... perhaps not enough room.
 22 February 2019 08:26 PM
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IronFreely

Posts: 445
Joined: 06 November 2014

Sounds like you're installing a completely new sub main which begs the question is it not easier and possibly more appropriate to install a metal consumer unit.... If it's a building attached to a dwelling it really should be metal.
 22 February 2019 08:32 PM
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mikejumper

Posts: 2810
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Have done similar with 10mm 3 core SWA.

Can't see a problem.
 22 February 2019 08:37 PM
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Baldyhugh

Posts: 413
Joined: 01 June 2007

Originally posted by: IronFreely

Sounds like you're installing a completely new sub main which begs the question is it not easier and possibly more appropriate to install a metal consumer unit.... If it's a building attached to a dwelling it really should be metal.


It's a farm so IP44 applies so plastic consumer unit is the only option. The building is remote from any domestic dwellings
 22 February 2019 08:38 PM
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Baldyhugh

Posts: 413
Joined: 01 June 2007

Originally posted by: psychicwarrior

or ... 32mm coupler and bushes perhaps (or even just a brass bush and nut)... perhaps not enough room.


Yes I could try a bush and locknut as I could get away with bigger than 32mm if needed. Thanks
 22 February 2019 08:45 PM
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OMS

Posts: 22864
Joined: 23 March 2004

The adaptable box is likely earthed from the SWA (and possibly with the 3rd core onto the banjo and into the con unit

Other than that, personally, I'd take the bedding through but wouldn't be that concerned if it wasn't

You don't mention earthing arrangements so my initial comment may be skewed and you are using the AB to gap the earthing to a TT for the con unit



Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 22 February 2019 08:53 PM
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Baldyhugh

Posts: 413
Joined: 01 June 2007

Originally posted by: OMS

The adaptable box is likely earthed from the SWA (and possibly with the 3rd core onto the banjo and into the con unit



Other than that, personally, I'd take the bedding through but wouldn't be that concerned if it wasn't



You don't mention earthing arrangements so my initial comment may be skewed and you are using the AB to gap the earthing to a TT for the con unit


Hi OMS

No it isn't being used to change earthing systems which remains continuous




Regards



OMS
 22 February 2019 11:10 PM
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mapj1

Posts: 12039
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I have done exactly this sort of thing on a few occasions, and in other cases glanded onto a right angle bracket in plastic trunking.
Remember you are allowed quite large gaps into enclosures for basic insulation, so long as no live parts are accessible, "IPXXB or IP2X" is surprisingly generous,.

-------------------------
regards Mike
 23 February 2019 10:03 AM
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IronFreely

Posts: 445
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Fair enough, if plastic is the only way your plan sounds like a good one. I often use a plastic whiska box to terminate SWA before a shed consumer unit so as to isolate the PME from a shed TT island...
 23 February 2019 10:03 AM
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IronFreely

Posts: 445
Joined: 06 November 2014

Fair enough, if plastic is the only way your plan sounds like a good one. I often use a plastic whiska box to terminate SWA before a shed consumer unit so as to isolate the PME from a shed TT island...
 23 February 2019 10:33 AM
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Baldyhugh

Posts: 413
Joined: 01 June 2007

Ironfreely

Current earthing system it TT so no need to create separate island in my case but have used your example myself a few times
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