SWA Earthing

So,a 10 metre run of 6.00mm twin and earth, which has a 2.5mm cpc.( although some have 4.0mm)

You don't say how big the SWA is.

You don't say how many cores the SWA has.

The general consensus seems to be that if the supply and earthing characteristics are PME, then you earth the armour back to the cu but do not use it as an earth for the hot tub end. The hot tub end should be TT'd with a rod and provided with RCD protection as required.

6.00mm twin and earth, which has a 2.5mm cpc.( although some have 4.0mm)

Not that I'm aware of and be compliant, it is normally the 10 mm2 that people think has 6 mm2 but it is only 4 mm2.

Regards

BOD

The common standard by suppliers for 6.0 is indeed 2.5 but you could have it other sizes which usually means bespoke which usually means no thanks it`ll cost too much. I must admit that I see why some others think our reduced cpc sizes are a bit strange as it makes a bog standard short cct more than half mains voltage as a starting point on T&E etc (except 1.0) OK para paths sometimes mitigate some things but yes I accept that we are viewed to be a bit strange. 

Ring finals puts others off too 

whjohnson: 
 

So,a 10 metre run of 6.00mm twin and earth, which has a 2.5mm cpc.( although some have 4.0mm)

You don't say how big the SWA is.

You don't say how many cores the SWA has.

The general consensus seems to be that if the supply and earthing characteristics are PME, then you earth the armour back to the cu but do not use it as an earth for the hot tub end. The hot tub end should be TT'd with a rod and provided with RCD protection as required.

As above follow 702 for hot tubs located outdoors TT.

whjohnson: 
 

The general consensus seems to be that if the supply and earthing characteristics are PME, then you earth the armour back to the cu but do not use it as an earth for the hot tub end. The hot tub end should be TT'd with a rod and provided with RCD protection as required.

But note that  simultaneously-accessible exposed-conductive-parts cannot be connected to different earthing systems. Regulation 411.3.1.1.

If this is a small-curtilage property, that could be an issue because of extension leads. Even if you check everything “fixed” is OK when you leave the installation, the use of extension leads must not be possible - remember the users of a domestic installation are usually not skilled or instructed persons (electrically) as defined in BS 7671.

Don't hot tubs come with a 13A plug and RCD molded into the supply cable?

Plenty of pictures of melted plug and sockets on Twitter from hot tubs. Most run at around 16amps so worth checking before relying on a supplied hot tub plug.

Just before it enters outside I have then used a Junction box to connect this with SWA. As the SWA only starts 10m away from the Consumer unit will I need to run a separate earth cable for the armour back to source (Consumer unit)?

Provided all the sizes c.p.c. calculations check out OK then you'd just connect the armour of the SWA to the c.p.c of the T&E (along with any core of the SWA cable you're using one as an additional c.p.c., if any).

   - Andy.