SWA to twin & earth juntion box?

[JGH1948]

I'm powering up an outside office and greenhouse heating and have established I need a 10mm SWA for the load and distance from the house to the locations. Inside the house I plan to run 10mm twin & earth from the consumer unit to the wall where it meet the SWA. What would be the best connector/junction box to use between the two types of cable?

 

[plugwash]

A round galv conduit box would be a neat option but you may find it a bit of a squeeze to join the cables in there. If you want a bit more wiring room use an adaptable box.

 

[barch]

I'm doing much the same thing. On the Wiki on here, it mentions earthing the SWA cable with a gland at either end. How does this wrok? I'm going to have a weatherproof termnal box on the wall of the house from which the SWA cable will drop down the wall into the ground and covered by slab. Do I slip a gland over each end where the cable enters the ground and run an earth wire back to the main earthing point?

thanks

 

[Taylortwocities]

Nope, you use an SWA gland and the banjo (supplied with the gland). You then connect the banjo to earth at the supply end. This provides the protective earth for the cable itself.

Your cable should be three cores with one of the cores being the earth for the circuit.

Make sure it is for outdoor use & the right size for the cable u are using. They look like this:

when assembled they look like this:

 

[barch]

thanks, understood

 

[JGH1948]

Many thanks.

 

[Lectrician]

10mm in a galv round through box would not be possible! You just wouldn't do it.

I would use a gewiss 4x6x2 enclosure. Use some 60amp terminal blocks, or fit some rail and use some dinrail terminals.

Are you going to bring the T+E into the rear? Make sure you make the hole in the lower part of the box, drill a drain hole, make the cable entry the size of the cable (two round holes made into a long hole), and use some non-setting compout to seal the hole - Perrelli make some, and it is available all good wholesalers.

 

[Cremeegg]

You could always try these Piranha nuts for your SWA termination http://www.tlc-direct.co.uk/Products/PRPEN20.html makes getting a good earth easy for those inexperienced with SWA glands. You can always use 2 core SWA and use the armour as the earth as intended but many prefer to use a third core as earth. If you do you'll still need to earth the armour.

 

[Taylortwocities]

You can always use 2 core SWA and use the armour as the earth as intended but many prefer to use a third core as earth. If you do you'll still need to earth the armour.

Yes I agree you are technically correct, however, the practicality of achieving a good connection by a DIY'er using this method leaves a lot to be desired. Making off a gland with swa is difficult enough without assuring continuity of the armouring at both ends.

Also you need to do a complicated calculation to ensure that the armour is sufficient to for the job as earth. Again outside the realms of this (DIY) forum.

 

[JGH1948]

A good site for calculating cable sizes - not taking into acount diversity is: www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html.