PLASTIC CONSUMER UNITS

[ian_1980]

Hi, I need a consumer unit in a outside shed. I was wondering if its safe to run SWA cable from the house into a shed using a plastic consumer unit then run the SWA cable back out into a second shed using a metal consumer unit. Is this safe as I understand that the armour of the cable acts as a earth and would be broken if a plastic consumer unit is in the middle or is there a metal shield inside these plastic units to act as a earth?

 

[RF Lighting]

You would need to terminate the SWA into a metal adaptable box.

 

[ian_1980]

Thanks for your reply.
So what I will do is run the plastic consumer unit into a piece of Galvanised Steel Trunking just under the plastic consumer unit and terminate the SWA into the Galvanised Steel Trunking.

 

[bernardgreen]

Thanks for your reply.
So what I will do is run the plastic consumer unit into a piece of Galvanised Steel Trunking just under the plastic consumer unit and terminate the SWA into the Galvanised Steel Trunking.

I terminated SWA using a die cast box screwed to the wall.

SWA stripped and glanded to one end of the box and the tails, together with the earth from the banjo, taken out through a grommeted hole at the other end and up into the consumer unit.

No joints in the box, the SWA was stripped back so the tails were long enough to reach the consumer unit terminals

An extra earth was made to a bolt in the side of the box.

Same arrangement both ends.

 

[ELZ4742]

You would need to terminate the SWA into a metal adaptable box.

why?

 

[RF Lighting]

Because plastic is not suitable for glanding an armoured into.

 

[ian_1980]

I have found a couple of metal adaptable box to use suggested by RF Lighting on this site
http://www.screwfix.com/search.do;j...FFY?_dyncharset=UTF-8&fh_search=adaptable+box
I will just terminate just the glands of the SWA to the adaptable box and make the leads long enough to run up into the consumer unit.
Will the extra earth be necessary to earth the adaptable box from the earth in the cable/consumer unit?

 

[RF Lighting]

Yep one of the galvanised adaptable boxes will be fine.

You need to take an earth from the consumer unit, and connect it to a bolt through the hole in the earthing banjo and adaptable box. (supplied with the gland pack.

 

[Steve]

Bernard is it me or have you had need to use that photo 3 times in the last week?

Here's mine, same method as yours really:

 

[jj4091]

Because plastic is not suitable for glanding an armoured into.

Do you mean just from a physical strength point of view or is that a reg that I have missed?

 

[securespark]

I have terminated SWA into plastic before now, but it needs to be sturdy stuff, or else it distorts & rips. Fit a banjo on the outside and pass a brass M4 panhead screw with washers through & put a nut on the end. Once connected via a flying lead to the cpc, this gives earth continuity to the armour.

If there's space, you can fit the banjo inside, bending back the tab so as to fit a flying lead onto it.

 

[ELZ4742]

^^What he said. you can gland into pretty much anything that will take it.

 

[bernardgreen]

Bernard is it me or have you had need to use that photo 3 times in the last week?
Here's mine, same method as yours really:

Yes THREE times. I may show the other end next time, just for a change.

I had to use a die cast box as the OD of the SWA is 27mm and the tails (16 mm) were too stiff to bend so they had to go straight through the other end.