Terminating SWA

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Hi,
I am putting a 4mm SWA cable from the house to an outbuilding. The outbuilding will have a small consumer unit.

Does anyone have any suggestions on how to terminate the SWA wire armour neatly into a consumer unit. The only thing I can come up with is to gland the cable off using an angle bracket near to the consumer unit, then take the 2 cores, earth core and earth from the gland into the consumer unit at each end.

BTW do you have to connect the armour to ground at both ends?
 
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Hi,
I am putting a 4mm SWA cable from the house to an outbuilding. The outbuilding will have a small consumer unit.
Have you notified the council yet?

Have you taken voltage drop and EFLI into consideration with the choice of cable?

Do you know how to correctly route the cable?

Do you have TNC-S earth export issues?

Do you have the ability to test the sub-main and new final circuits?


Does anyone have any suggestions on how to terminate the SWA wire armour neatly into a consumer unit.
It won't go into the CU itself?


The only thing I can come up with is to gland the cable off using an angle bracket near to the consumer unit, then take the 2 cores, earth core and earth from the gland into the consumer unit at each end.
Better to use an adaptable box butted up against the CU, that way you won't have exposed cores.


BTW do you have to connect the armour to ground at both ends?
Yes.
 
:oops: :oops: That's true :oops: :oops:

Although if the armour csa is large enough and you've elected to extend the house equipotential zone by bonding to the e-c-ps in the garage....
 
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I have checked the volt drop and current capacity and both are OK acording to the 17th edition tables.

What are the earthing issues and how do you check things out.

The BCO is aware of the works, and the finished install will be checked by an electrician and signed off when complete.

The cable will be put in a trench covered with warning tape etc at the correct depths.
 
just on a tangent, do sub mains have to be armoured?

No, just because it is a submain doesn't mean it has to be armoured. However if the cable is being installed outside or underground then armoured is probably the best way to go.
Instead you may install another cable type such as MICC, or you can even install another type of unprotected cable in plastic conduit above ground or earthed metal conduit if underground. If there is risk of impact above ground tho placcy conduit wont be suitable. A long run in placcy conduit might not work very well either.
Generally every cable must be selected taking into account its environment, if you are running a submain in to a CU for a kitchen which involves running between floorboards you can get away with flat twin and earth.
 
the finished install will be checked by an electrician and signed off when complete..

How will you arrange that then? Most registered sparkies are only allowed to notify works that they have done, themselves.

You may be able to get a spark to agree to work with you but he will want to be involved in all aspects of the design and oversee the installation.
 
back to the original question.

terminate it in a steel adapatable box under the CU
 
At the main CU end, I use a galv. through box, terminating the cable in a gland which is then screwed into one side of the box, the other butts up to the CU body (insulated cu). The tails are then left long enough to go right through the galv box into the CU & terminate there. Then I use a g/y single to link to the galv box.

At the other end, I use a metalclad CU & attach the gland direct to the CU.
 
just on a tangent, do sub mains have to be armoured?
They don't HAVE to be but afaict it's generally a good idea for them to be armoured or protected by earthed metal.

Generally you do not want submains to be on a 30ma RCD if you can avoid it. There is the skilled or instructed person exception but you generally can't really apply that on domestic work and on commercial work while you may be able to apply it with the present use of the building there is no gaurantee things will stay that way.

Submains also tend to have high current ratings making them higher risk than most other circuit types.
 

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