Outdoor Socket Fitting - Advice

[LENNYLENNY16]

Hi all,



I'm looking at getting an outdoor double socket fitted. I'm hoping for some thoughts from the forum who have already provided a lot of valuable help and advice.

Any work will be completed and signed off according to regs by suitably qualified electrician.



The planned setup is to be as follows. The codes are Screwfix product codes for the items planned to be fitted:



1. 2.5mm T&E off the back of an existing internal ring main socket - TO -



2. 13a metal clad switched fused spur (737PF) with 2.5mm T&E with 2.5mm T&E - TO -



3. 13a metal clad RCD spur immediately next to this (4323P) where SWA will terminate.

(Both metal clad spurs surface mounted next to one another in cupboard close to ring main socket supply) - WITH -



4. The 20mm SWA terminated and earthed from metal clad RCD spur with approximately a 15m underground cable run to double outdoor socket (67928). SWA earthed at both ends using earthing nuts (77809).



Hopefully this makes sense. Any thoughts/suggestions/concerns with this planned arrangement please?



Many thanks in advance.



 Lee

 

[brianmoooore]

Nothing to be gained by fitting a RCD, assuming that the ring is already served by one (which I should hope it is, since we're a quarter of the way through the 21st century). The spur isn't required either, if it's just a single 2G socket being fitted, but it will form a useful connection point between T&E and SWA, and an indoor isolator for the socket might pay dividends at some point.
It's quite a long spur in 2.5mm2, so loop and VD needs to be considered for compliance.

 

[Risteard]

Along with the above remarks, I would suggest that a metalclad accessory outside is not appropriate. You mention this being signed off by an Electrician, but realistically any Electrician will insist on doing all works to do this. (And supply any materials.)

 

[LENNYLENNY16]

Nothing to be gained by fitting a RCD, assuming that the ring is already served by one (which I should hope it is, since we're a quarter of the way through the 21st century). The spur isn't required either, if it's just a single 2G socket being fitted, but it will form a useful connection point between T&E and SWA, and an indoor isolator for the socket might pay dividends at some point.
It's quite a long spur in 2.5mm2, so loop and VD needs to be considered for compliance.

Thanks for the quick reply.

The ring is RCD protected.

So the setup but removing the RCD and just having the switched spur for isolation purposes would work?

RE the length, the majority of the distance will be covered by the 20mm SWA not the 2.5mm T&E which will only be about 0.5m maximum. Does that make much difference?

Thanks again for your advice here.

Lee

 

[LENNYLENNY16]

Along with the above remarks, I would suggest that a metalclad accessory outside is not appropriate. You mention this being signed off by an Electrician, but realistically any Electrician will insist on doing all works to do this. (And supply any materials.)

Thanks for your quick reply here.

The metal clad boxes will be internal inside a cupboard indoors. The SWA will go from the metal clad box through a buried conduit to the outside and on to the socket.

The conduit and SWA was fitted previously when we had our Fibre Optic broadband fitted un anticipation of this socket being fitted at a later date.

I'm getting the materials and it will all be fit by a sparky. I am just curious and keen to know the best way of doing this taking different expert opinions in to account.

Cheers
Lee

 

[littlespark]

Are you doing this yourself?

Sorry if that’s incorrect, but it’s better just to say so at the beginning, rather than say there’s an electrician involved as all you get are comments saying “the electrician will get everything you need”

Beyond the legalities of part P notification, if required, and the need for issuing a test certificate…. We can advise better if we know if it’s going to be a diy project, or if indeed an electrician will be there.



My opinions…

A switch fuse off the ring. The 13A fuse means you can have as many sockets downstream as you like. And serves as an isolation point. (Double pole switch)

Outside to the weatherproof socket from screwfix. No problem there, I’ve got 3 myself on different corners of the house

From here, your armoured cable. 20mm is simply the size of gland you need, and covers quite a few sizes of cable. Stick to 2.5mm, because of the 13A fuse. Use weatherproof glands.
The armour of the cable needs to be earthed. At one end if you use a 3 core cable, at both ends if 2 core cable and using the armour as the earth wire.

And, I would like to know what the load would be. Is it just power to a light in a shed, lawnmower etc, or are we talking a hot tub, outside heaters etc?

 

[brianmoooore]

And, I would like to know what the load would be. Is it just power to a light in a shed, lawnmower etc, or are we talking a hot tub, outside heaters etc?

Not relevant, in my book. Design load is 20A if no 13A fused spur, or 13A if there is. You design for the life of the installation, not just the customer's immediate requirements.

 

[littlespark]

Not relevant, in my book. Design load is 20A if no 13A fused spur, or 13A if there is. You design for the life of the installation, not just the customer's immediate requirements.

You design for the load and work from there.

Customers might ask for “a socket in the shed” but what they really need is a bigger supply.

And with people asking for sockets for EV granny chargers as an example…. spurring off an already heavily loaded ring (like a kitchen) may not be adequate.

 

[Mike Johnson]

Outside sockets usually supply a hot tub.

 

[mainline]

The armour of the cable needs to be earthed. At one end if you use a 3 core cable, at both ends if 2 core cable and using the armour as the earth wire.

Generally it would depend on the circumstances whether the armour is earthed both ends or not, and not just dependent on whether it's 2 or 3 core.

If earthing only one end, that end should be at the source.

The armour of both ends should be earthed, unless it's something like a TN to TT supply.