UK DIY- advice on extending wiring into new shed

[swisstony]

Hi all, DIY here
First off let me just say it is advice I am after as I am fully aware that I will probably need an electrician to complete the job. My question is how much I can do myself up to a point.
So many years ago I built a shed at the top of the garden ( approx 30m away from garage). I needed power and lighting to the shed so purchased the armoured cable, fixings, outdoor sockets etc (on the advice of my sparky) and did the labour myself of digging the trench from the garage (where the feed would be ) laying the cable including tape, drainage etc. Then my sparky came in and did all the easy work Actually he was brilliant and connected up all the power, changed the fuse in the main board, added in lighting and fitted the exterior sockets for the garden. Tested and provided me with the certificate. All good.

So my next plan is to build even a bigger second shed behind the first one . During this lockdown project a man's got to have a project ! So I am building it myself over the course of the next few months. It will be positioned around 2 feet away from the first shed ( have attached a small rough diagram) . So the question at last : I would like to have power and lightning in the new shed (approx 10ftx8ft) pent roof style. So given that it will be so close to the old shed , how hard is to extend the power and lighting circuit into the new shed ? I will be using it as a small wood workshop so will need power sockets around the perimeter at worktable height. Probably about 4 double sockets. Lighting will be simple LED shop lights x 2 on the ceiling. nothing fancy.

How much could I do for the prep work ?
would it be an extension from inside the old shed across to the new shed or would it be a spur from the original feed ?
power tools are all 220V , I don't have any that are 110V

Thank you for any advice
cheers

 

[Baddegg]

What size cable and fuse/mcb are feeding the original shed mate?

 

[swisstony]

What size cable and fuse/mcb are feeding the original shed mate?

good point, I guess I could find that out by looking back at the invoice he sent me ?

 

[buzzlightyear]

given that it will be so close to the old shed , how hard is to extend the power and lighting circuit into the new shed ?

with out bursting your balloon, I would wait till this pandemic is over and get the spark back when he did the first shed.You mess up it will cost you, it is not easy until you know what you are doing.

 

[Baddegg]

good point, I guess I could find that out by looking back at the invoice he sent me ?

Possibly mate....have a look and let’s us know, you should be able to determine the protective device for the armoured by looking at your consumer unit or post up a picture

 

[swisstony]

with out bursting your balloon, I would wait till this pandemic is over and get the spark back when he did the first shed.You cock up it will cost you, it is not easy until you know what you are doing.

true. I wasn't trying to do it all myself. I was seeing how much legwork I could do myself in readiness when everything has calmed down
[automerge]1585900154[/automerge]

What size cable and fuse/mcb are feeding the original shed mate?

can't find the original order for the SWA cable but attached is his minor works , that may help
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Possibly mate....have a look and let’s us know, you should be able to determine the protective device for the armoured by looking at your consumer unit or post up a picture

I know he had to change the fuse from 32A to 20A as it was incorrect. Think he mentioned it in his invoice
Like "
Install a 20 amp Contactum MCB in consumer unit to replace existing overated 32 amp one."

 

[Baddegg]

Looks like you’ve only got a 2.5 mm armoured cable there mate, what sort of woodworking equipment are you thinking?.....you’ve also left the sparks name and address on there mate....not cool ?

 

[westward10]

Attachment deleted. If you can obscure the contractors details you can put it back up.

 

[swisstony]

Looks like you’ve only got a 2.5 mm armoured cable there mate, what sort of woodworking equipment are you thinking?.....you’ve also left the sparks name and address on there mate....not cool ?

whoops sure he won't mind . nothing too major. I will have a chop saw, various other power tools, shop vac . Nothing that has a massive draw that I can think of and none that would be working at the same time .
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attachment edited !

 

[pc1966]

At a quick look then you should be fine if all you want to run is something that hangs off a 13A plug normally. For example a small lathe, drill, etc.

What is there in the old shed in terms of how the armoured cable is terminated? Is there a small consumer unit (fusebox) to split it between the lights and 13A socket, etc?

You really have two options for the cable run. Obvious and proper one is another short run of armoured cable underground between the two sheds. For that you would need more of the same 2.5mm SWA cable but make sure you leave plenty to allow easy termination at both ends by the electrician. If digging then obviously take great care not to damage the existing wire!

But given short distance span, if high enough not to be a hazard if you are doing any maintenance, and properly supported (by metal conduit or a steel wire, etc), you could run some outdoor rated cable overhead between them as an alternative to buried cable.

 

[buzzlightyear]

A minor for a new supply to a shed I don't think so.

 

[westward10]

2.5 over 30m, 20A protective device exceeds the 3% volt drop for the lighting as it stands now.

 

[swisstony]

2.5 over 30m, 20A protective device exceeds the 3% volt drop for the lighting as it stands now.

At a quick look then you should be fine if all you want to run is something that hangs off a 13A plug normally. For example a small lathe, drill, etc.

What is there in the old shed in terms of how the armoured cable is terminated? Is there a small consumer unit (fusebox) to split it between the lights and 13A socket, etc?

You really have two options for the cable run. Obvious and proper one is another short run of armoured cable underground between the two sheds. For that you would need more of the same 2.5mm SWA cable but make sure you leave plenty to allow easy termination at both ends by the electrician. If digging then obviously take great care not to damage the existing wire!

But given short distance span, if high enough not to be a hazard if you are doing any maintenance, and properly supported (by metal conduit or a steel wire, etc), you could run some outdoor rated cable overhead between them as an alternative to buried cable.

I would have to have a look but I can't recall anything.

I like the idea of the overhead run as it is such a short span and could be raised high enough to carry an outdoor rated cable . Apart from the build itself once the roof is on I doubt I will be doing any regular maintenance up there, probably guttering height and that will be it.

 

[pc1966]

2.5 over 30m, 20A protective device exceeds the 3% volt drop for the lighting as it stands now.

The measured R1+R2 of 0.21 ohm implies a 2% drop at 20A, and from some data sheet on BS5467 cable the SWA is about the same impedance as the conductors so possibly the length is only 11m? Or maybe it really was 4mm SWA cable fitted?

Something is a little odd there!
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I would have to have a look but I can't recall anything.

I like the idea of the overhead run as it is such a short span and could be raised high enough to carry an outdoor rated cable . Apart from the build itself once the roof is on I doubt I will be doing any regular maintenance up there, probably guttering height and that will be it.

At a distance of only 2 feet you could probably use a length of 3" (or whatever) plastic drainpipe between sheds (glued/sealed in place with silicone sealent) and it would be self-supporting, then simply feed a 13A extension lead through as a temporary measure.

 

[barninks]

A minor for a new supply to a shed I don't think so.

The way the OP is written it sounds like it might be an extension off another circuit? But that doesnt really make sense with the breaker change etc?