Garden Socket - Sockets from SWA

[Ra Suhl]

Hi Folks,

I moved into a house that had an existing SWA cable (20mm, 4-core) going from the house CU (RCD) up the garden to a smaller CU in a brick shed (about 80 feet away). When the house clearance people were clearing the garden they thought it wise to burn all the old weeds and ended up burning through the SWA's sleeve. I've since spliced in a new length of SWA cable using 2-way Pratley junction boxes.

Moving forward a couple of years, I'd like to have some outdoor sockets in the garden to feed a pond pump and a few lights. I've purchsed a couple of BG IP66 double sockets (WiFi/smart) and was intending to take a feed from the existing SWA using a 3-way Pratley junction box as shown in the diagram below.

Is this feasible/safe? I'm confident in undertaking the preparatory work (measuring, cutting cables and installing the sockets etc.), but would leave the final connections to a qualified electrician as I'm aware of the risks and regulations. I'm just unsure of whether taking a line from the main cable would affect the stability of the supply and whether it needs to be in parallel/series.

Thanks in advance.

 

[ericmark]

Looking at the outside diameter of 4 core SWA cable it could be 2.5 mm², 4 mm² or 6mm² depending on the make and type of cable, and it will need protection to suit the size used, and any new sockets will need RCD protection. As to earthing normally a SWA gland is used and the SWA carries the earth, but not always, in some cases the out building is on it's own earth using a TT system, which can be safer.

So there is no yes or no answer. this old publication on outbuildings supply and this on broken PEN may help.

In Wales where I live the garden is a special location and needs notifying under Part P building regulations, and I think there is a good reason as so easy to get things wrong.

 

[Ra Suhl]

Thanks for your reply. My mistake - the cable diameter is about 14mm, with 4-core 2.5mm²:

https://www.tlc-direct.co.uk/Products/SW2dot5slash4.html

Cheers.