Putting sockets in the garden... best way

[spookly]

Probably a bit of a repeated question.... BUT....

I am in the process of paving my entire back garden at the request of SWMBO. She is also asking for a single and a double socket to be installed in the garden. Obviously these will need to be IP56 rated etc.

The patio is not yet laid, so I am open to possibly digging the cable in but want to explore what may options are.

The nearest power is on a RCD protected (at the CU in the house) mains ring that supplies only the kitchen (this ring is separate from the CU supply to the cooker and fridge/freezer .

1) Can I run a fused spur from this mains ring outside to the first socket (single socket about 5 metres away), and then run the cable straight on to the second socket (double socket) about a further 10 metres away?

2) Is it absolutely neccessary to bury the cables, or can I just use PVC conduit running along boundary walls with T&E inside (is that allowed??). What options are there? I can still bury the cables as the patio is not yet laid, but conduit might be preferred as it will be far easier to move things later if required.

3) What size cable would I need. The only things that would be plugged into the sockets would be:
* 1500W pressure washer
* Occassional power tools, nothing heavy... circular saw/router up to 1Kw
* external lighting, no more than 500w maximum (filament/low energy mains type, not halogen or LV).

At the moment I am thinking that burying the cable is probably best (at least 450mm deep, I recall others saying?). Can I just use SWA and bury it at the correct depth, properly marked/protected etc?

Does SWA that is above ground need to be run in conduit? So if the SWA came out through a wall, and down the wall into the ground would it need any protection?

Part P disclaimer..... My BIL is a qualified sparky and inspects all my work prior to it getting turned on, so no danger of it being a train wreck. He just prefers that I don't bother him until I need something inspecting/signing off/certifying (or whatever it is that needs doing)... which suits me fine as he is a bit of an ar5e. So no part P references please.


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[Chri5]

If the boundary wall is a permanent structure (not wood fence) such as brick then it's perfectly acceptable to use as a cable fix point.

You should make sure the run is not likely to suffer from mechanical damage.

If 13a fused spur, then 13 x 230v = 4000w odd can run off the external sockets.

As a personal prefrence I would prefer to provide the external as a direct circuit if you have a spare way on the RCD split and rate it as 10/ 16 or 20 amp via SWA 3 core 2.5mm.

I'd also consider a 20a switch as further isolation between the cu and sockets.

SWA is quite lumpy and if you use conduit (which serves no purpose) you would have to earth it and will have issues on bends and route changes along the conduit run. SWA can be surface run or buried.

Make sure you mount the sockets at a decent height and away from fauna.

 

[spookly]

Thanks Chri5.

I would consider running it direct from the CU, but the CU is under the stairs in the middle of the house, and I don't fancy pulling up floors to route the cable from there to the back garden.

So the best option looks like 2.5mm 3 core SWA, either buried (suitably) or not. I think I'll definitely run it from a switched fused spur from the kitchen ring.

One more question.... connecting SWA into the ring... how?
Will I need a particular junction box, or can the SWA be wired directly into the existing sockets? If I need a junction box, and chance of a link to the type of thing I'd require?

As far as mounting the sockets goes, I was thinking of mounting one a couple of feet up a tree (fairly permanent ), and another screwed a couple of feet up an old stone wall (again, quite permanent).

Thanks for the advice so far.

 

[spookly]

Sorry, forgot one other thing.

Do I run the SWA cable out to the first socket, and then in series on to the next socket?

Or (preferably) can I run the SWA out to a junction box which then feeds directly to the two different sockets?

Probably a silly question, but I'd rather get it right.

 

[SeanT]

You can do pretty much whatever you want, after the switched fused spur (other than running really really long cables that is...)

 

[Taylortwocities]

Do I run the SWA cable out to the first socket, and then in series on to the next socket?

.

In parallel......

 

[scousespark]

Part P disclaimer..... My BIL is a qualified sparky and inspects all my work prior to it getting turned on, so no danger of it being a train wreck. He just prefers that I don't bother him until I need something inspecting/signing off/certifying (or whatever it is that needs doing)... which suits me fine as he is a bit of an a**e. So no part P references please.

Sorry to butt in but there is no Part-P disclaimer for adding outside sockets spurred from a kitchen. It's notifiable.

You either notify LABC yourself, or use a registered electricain.
Your BIL can't sign off for work he hasn't done (unless he oversees the job and is registered).

 

[spookly]

Thats kind of the point.

My BIL oversees the work by popping in regularly and inspecting it before I bury anything, and then testing it before he signs it off.

I'm aware that its notifiable work under part P. Hence the disclaimer to tell people that I'm not interested in replies saying that its part P notifiable.

Cheers for the replies.

 

[Chri5]

You shouldn't mount anything on a tree- they grow! And cable isn't elastic

I'd suggest you terminate the SWA in http://www.tlc-direct.co.uk/Products/WK607B.html

http://www.tlc-direct.co.uk/Products/TLC20.html

and use these (optional)

 

[spookly]

If the closest socket on the kitchen ring already has a spur can I use a junction box on the ring and spur off of this, or will I have to add another socket and spur off of that?

----------ring---------[junction box]--------ring------------

 

[bongos]

Slightly confused - do you mean this?

{ring}----[socket/spur]----[Junction Box]----[socket]----{ring}

I believe you could do this although having an extra socket could be more beneficial than a junction box. Not sure how easy it would be to terminate SWA in there!

The junction box would have to be accessible too. If its not going to be then you can't use it to join cables.

 

[scousespark]

Why not ask your BIL?
I don't understand an electrician leaving you struggling with your design decisions. Without being on-site it's impossible to advise you the best way forward.

If you put in a JB in, it has to be accessible.
If there is already a spur, you could put in an FCU and add your spur.
This limits the current outside to 13A, so may not be okay. It's down to what you think you are going to use outside.

 

[Chri5]

Break the ring with a fused spur, run a bit of TE between spur load and the external junction box (keeping the TE internal and then direct through wall to external jb), terminate TE and SWA inside jb and off you go.

 

[ban-all-sheds]

I'd suggest you terminate the SWA in http://www.tlc-direct.co.uk/Products/WK607B.html

I wouldn't, based on recent experience.

The threaded holes are fine for plastic compression glands, but it would be a case of the tail wagging the dog with brass CW armoured ones, and there's no room inside for piranha nuts or banjos, and there are ribs and other mouldings which prevent locknuts from sitting properly.

 

[ban-all-sheds]

If 13a fused spur, then 13 x 230v = 4000w odd can run off the external sockets.

Q1. 13 x 240 =

• 4000
• 0.05
• 3120
• 18.46