UK Advice on outdoor circuit please

[MatcherMike]

Hi All,

Appreciate some advice on an outdoor socket and lighting circuit please.

I currently have an outdoor socket on my house, that i believe to be a spur from a 32A ring. I would like to extend this out to decking for some lights and sockets, and onward to a shed for a couple of lights and 3 sockets.

I believe i can - Changed the socket to a fused spur (13A?) and from this run 4mm SWA to my decking and from here it will onward run to the shed. The socket to decking run is 17m, as is the decking to shed run. So my thoughts were this:

13A FSU in place of outdoor socket
4mm SWA to decking, terminated in an IP66 enclosure.
4mm SWA from this enclosure onto the shed, terminated directly into a 2g socket.
2.5mm run onward from this socket to another 2g socket, and one further on from this.
5A FSU hanging off the first 2G socket in this location, to provide a lighting circuit.
Switch and light unit wired in 1.5mm from this 5A FSU

Does this work?

Back on the decking. Do i need to connect my sockets here in radial, or can these spur off the 4mm SWA junction box?

So from junction box, go 4mm SWA to a 2G socket
From this socket 4mm SWA to another 2G socket
From this final 2G socket, go 4mm SWA to a Knightsbridge remote switch unit (5 circuits all fused individually).

How does this sound? I think i am fairly confident about the bit to the shed, but don't know about the decking bits and how i would wire them into the circuit.



Any advice very gratefully appreciated.

Thanks
Mike

 

[pc1966]

First question, is your socket already on a RCD protected circuit?

Second question, and fundamental to all of this, is what sort of a load do you expect to have? If the total is less than 13A you can do it that way.

However, you need to properly terminate SWA cable, it won't simply go in to a FCU and some will struggle to take 4mm cable (as usually a 13A appliance is no more than 1.5mm or 2.5mm at most).

Do you actually need SWA? Short version, will you bury it or need it to be protected against damage (odd kick, glancing blow, mice, etc)? If not you can make life a whole lot easier by going for something suitable for outdoor use such as HO7RN-F in 2.5mm or so. At that point it might be simpler just to put it on a 13A plug to your existing socket.

Realistically if you need more than 10A regularly, or if you need high reliability/availability for any hobby/work use, then get a professional to put in a dedicated circuit for it.

 

[buzzlightyear]

looking at the idea of adding more gear for a existing circuit, it would be better to get a spark in to design and and test the circuit and putting in a new circuit for the loading.

 

[pc1966]

For your decking area you will find most double outdoor sockets have multiple cable entry points so it is easy to use plastic glands to have the cable going in-out as a daisy chain. Try to use the bottom ones, side at most, to reduce the risk of water getting in.

Simply looping though and on to the shed is simplest. For lights just put them on a 13A plug with 3A fuse or similar in to one of the double sockets (proper ones with latching lids).

If you do decide to do this make sure you have some way of testing it, a socket tester at the very least!
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Even if you want to bury the cable on part of the route, it might be easier just to put in duct and then feed the rubber cable through with a draw string.

 

[Pete999]

Hi All,

Appreciate some advice on an outdoor socket and lighting circuit please.

I currently have an outdoor socket on my house, that i believe to be a spur from a 32A ring. I would like to extend this out to decking for some lights and sockets, and onward to a shed for a couple of lights and 3 sockets.

I believe i can - Changed the socket to a fused spur (13A?) and from this run 4mm SWA to my decking and from here it will onward run to the shed. The socket to decking run is 17m, as is the decking to shed run. So my thoughts were this:

13A FSU in place of outdoor socket
4mm SWA to decking, terminated in an IP66 enclosure.
4mm SWA from this enclosure onto the shed, terminated directly into a 2g socket.
2.5mm run onward from this socket to another 2g socket, and one further on from this.
5A FSU hanging off the first 2G socket in this location, to provide a lighting circuit.
Switch and light unit wired in 1.5mm from this 5A FSU

Does this work?

Back on the decking. Do i need to connect my sockets here in radial, or can these spur off the 4mm SWA junction box?

So from junction box, go 4mm SWA to a 2G socket
From this socket 4mm SWA to another 2G socket
From this final 2G socket, go 4mm SWA to a Knightsbridge remote switch unit (5 circuits all fused individually).

How does this sound? I think i am fairly confident about the bit to the shed, but don't know about the decking bits and how i would wire them into the circuit.



Any advice very gratefully appreciated.

Thanks
Mike

Doing it that way you will bw limited tp 13 Amps though

 

[MatcherMike]

First question, is your socket already on a RCD protected circuit?

Second question, and fundamental to all of this, is what sort of a load do you expect to have? If the total is less than 13A you can do it that way.

However, you need to properly terminate SWA cable, it won't simply go in to a FCU and some will struggle to take 4mm cable (as usually a 13A appliance is no more than 1.5mm or 2.5mm at most).

Do you actually need SWA? Short version, will you bury it or need it to be protected against damage (odd kick, glancing blow, mice, etc)? If not you can make life a whole lot easier by going for something suitable for outdoor use such as HO7RN-F in 2.5mm or so. At that point it might be simpler just to put it on a 13A plug to your existing socket.

Realistically if you need more than 10A regularly, or if you need high reliability/availability for any hobby/work use, then get a professional to put in a dedicated circuit for it.

Hi, Thanks for taking the time to reply.

The socket is on a 32A RCBO.

I don't expect to have a great deal of load. Biggest will be in the shed which will have a timer for a tortoise light (EVO - Microclimate - https://www.microclimate.co.uk/product/microclimate-evo/) and a tortoise heat lamp (ceramic lamp and the thermostat adjusts its power accordingly). This is currently on a 13amp extension lead. This unit has it's own 5A fuse in it.

I won't use much else from here.

On the decking, i'll probably have that remote unit, with decking lights, some downlighters, and maybe some fairy type lights.

The sockets will possibly be used in future for an inflatable hottub. Plugging in a power tool if i am doing any adhoc projects and that is about it.

It will be buried in conduit i have already run into the ground. I know SWA needs terminating on glands with earthing to the shielding, but hoped this would be easy enough into standard outdoor sockets! I'll take a look at HO7RN-F. Maybe this will be suitable for the cabling on the deck.

It's not a big shed, and i won't be using it for anything. Just the things mentioned above.

Mike

 

[MatcherMike]

For your decking area you will find most double outdoor sockets have multiple cable entry points so it is easy to use plastic glands to have the cable going in-out as a daisy chain. Try to use the bottom ones, side at most, to reduce the risk of water getting in.

Simply looping though and on to the shed is simplest. For lights just put them on a 13A plug with 3A fuse or similar in to one of the double sockets (proper ones with latching lids).

If you do decide to do this make sure you have some way of testing it, a socket tester at the very least!
[automerge]1588707251[/automerge]
Even if you want to bury the cable on part of the route, it might be easier just to put in duct and then feed the rubber cable through with a draw string.

Thanks

For the lighting, i was going to go for something like this: Remote Controlled Switch Box IP66 - 5 Gang - https://www.tlc-direct.co.uk/Products/KBIP665G.html

Hardwire that into the junction box, or the last socket on the deck.

Mike

 

[MatcherMike]

Doing it that way you will bw limited tp 13 Amps though

Sure. I guess the alternative is a dedicated RCBO in my CU?

Mike

 

[Taylortwocities]

Sure. I guess the alternative is a dedicated RCBO in my CU?

Mike

Yes, but that would be a new circuit which would require notification to the local authority. Expensive for a small DIY project, alternatively you'd need to use a registered electrician.
Best to stick to 13A FCU plan, unless you have larger load.

 

[Pete999]

Sure. I guess the alternative is a dedicated RCBO in my CU?

Mike

Best get a Sparky involved Mike, difficult to advise from afar, good luck anyway

 

[pc1966]

Think through what you want now and longer term. If you can get away with a "glorified extension cable" for less than 13A it is an easy, cheap and quick route to having electric out there safely.

But if you want it more permanent, or want to have extra capacity, then get an electrician to look at it. You would end up with a dedicated circuit from your main board, but depending on the needs on reliability you might go for a fused-switch from the meter tails feeding the SWA cable instead of another RCBO.

Basically if you have a RCBO/MCB feeding the outdoor stuff you won't easily get selectivity with any down-stream protection. So if you blow a fuse on a 13A outlet it will probably trip the feeding MCB/RCBO as well as any local breakers. That may not matter to you if lights go off, etc, but in other cases it might be an issue (say you have a freezer on a 2nd circuit and you don't notice it has gone off and de-thawing everything).

However, if the feed SWA is of adequate size and so the feed fuse is relatively big (say 30A or more, but it depends on the downstream stuff) it will usually survive long enough for the down-stream fault protection to clear the fault.

Another factor in the cable / system design is if you need any earth bonding for "extraneous conductive parts" in the garage (steel structure, water pipes, etc) and you are on a TN-C-S supply (where your local earth and neutral are common up to the meter cut-out). In those cases you are required to have a minimum of 10mm copper-equivalent earth conductor size due to the potential high sustained fault currents if the PME goes open. Or you do a separate earth rod for a TT style of arrangement.

So plan what you want to do with all these factors in mind.