Anybody up to speed with the Electricity regs?

[spikey]

I'm given up trying to find this in the regs themselves, so can anybody tell me what the score is nowadays about running a power supply overhead to a shed that's 1.5M away from the house wall?  It would be 3-core 2.5mm SWA and I assume it would have to be on catenary, but what's the minimum clearance height above ground level?

 

NB. I know that this is a job for a professional sparky and he would know the answer.  My problem is that that height will determine if the job's a goer, and there's no point in getting quotes if it isn't.

[J. S. Bach]

I would call the pro (if quotes are free) and let they will let you know all of the details.

 

EDIT: I have the same problem with shed number three; I have decided that an extension cord from the shed to the outlet on the house will be sufficient. Just unroll the cord when I need to use it. Note that the only use for power would be lighting  the occasional dredging trip into the shed.

 

Shed number one shed already has power (buried) and shed number two is right next to it if I decide to do the same for it. Number two would be hard-wired to number one.

 

Edited May 18, 2023 by J. S. Bach

[Free At Last]

2 hours ago, spikey said:

 but what's the minimum clearance height above ground level?

High enough to pass under it.

At 1.5mtrs wide you won't be getting a double decker bus trying to get under it.

Edited May 18, 2023 by Free At Last

[Michael Hodgson]

I'm not a sparky and mine was done before the last couple of changes to the regs, but I think there is a strong preference for the cable to be run underground (and armoured or run in ducting) but I'm pretty sure overhead supported on catenary is still allowed for a short distances - but as you're not allowed to do the work yourself ask the contractor who quotes you.  Height does have to be enough so it isn't a hazard. You'll to to run it off its own circuit breaker in the house consumer unit, and the shed will want its own mini consumer unit (probably has to have RCD these days).

[96701]

 

[spikey]

Cheers 96701 🙂  That didn't come up with my searches, so your Google-fu is obviously far stronger than mine.  Anyhow, there's no sensible way to get 3.5M headroom and underground's a no-no, so no point in getting sparkies out to quote.

[2E Sub Shed]

Could you fix a vertical support to the shed to get the required height ?

Edited May 19, 2023 by 2E Sub Shed
Spelling !

[Derekl]

Mine was installed professionally about a year ago - the distance is about 1.5m and it is 2.1m above ground level. That may be of assistance. It is overhead supported by catenary.

[Jeremy Cumberland]

You only need 3 metres if you run it in steel conduit (>= 20 mm diameter, unjointed), which is a feasible option for a 1.5 metre span.

 

I suspect that many electricians turn something of a blind eye to the height limits for overhead wiring to a garden shed.

[Michael Hodgson]

Where the shed isn't tall enough I've seen people fit a simple mast to the end of the shed to raise the cable high enough to give their required clearance.

[spikey]

16 hours ago, 2E Sub Shed said:

Could you fix a vertical support to the shed to get the required height ?

 

Alas no.

[KeithMacdonald]

On 18/05/2023 at 19:16, spikey said:

what the score is nowadays about running a power supply overhead to a shed that's 1.5M away from the house wall? 

 

Is that metres or miles?

[Reorte]

How deep does a buried cable need to be? I've got a connection in to my shed from the past that I'm pretty sure doesn't meet the regs (of course it would depend on what they were when it was installed), and would prefer it to be buried. It probably won't be practical to do so (there's an area of decking in the way, pulling all of that up to dig a trench under it is more work than I want, especially since the planks have only recently been replaced), but it would be good to know what the options are.

[spikey]

FWIW I finally managed to get two sparkies to actually come and see what's what.  Neither have yet got back to me with a price, but I suppose it's early days yet.

 

Both opted to come off a twin socket on the kitchen wall, go through the wall, and run along it towards the shed.  From there, one favoured going to the shed via the rear elevation of the kitchen, over the annex doorway, along the bathroom wall and then across to the shed at a height of about 2.3M, the cable supporting itself across the 1.5M gap.  

 

T'other bloke has a far better idea: remove pointing between paving slabs 'twixt kitchen wall and shed, drop cable into groove, then up and through shed wall at about 50cm above ground level, re-point slabs and Bob's yer mother's brother.  This is obviously our preferred option, subject of course to the quote being affordable.

 

Both sparkies are established and suitably qualified.  Neither of them mentioned what the regs say ...

[spamcan61]

In terms of burying cable then some useful info here:-

 

https://uk.rs-online.com/web/content/discovery/ideas-and-advice/armoured-cable-faqs

[chris p bacon]

If you hide cable it needs to be at least 450mm underground with a tell tale strip 100mm above it.  I would never advise placing it in the joints between slabs, I'd be surprised if the armoured cable would actually bend that sharply between joints. 

 

I'd also be wary of tagging it onto the kitchen supply, this is usually (but not always depending on the age of installation) a separate circuit as it has the highest load in the house. The electricians that work for me always make any exterior supply a standalone circuit.

 

Out of interest are the electricians NiC EiC or another accreditation body?

[Reorte]

3 hours ago, chris p bacon said:

If you hide cable it needs to be at least 450mm underground with a tell tale strip 100mm above it.  I would never advise placing it in the joints between slabs, I'd be surprised if the armoured cable would actually bend that sharply between joints.

Interesting thanks, thought it would be deeper than that. Might be worth looking in to at some point then. Presumably the tell tale strip is something obvious that you hit before the cable to warn you it's there when you're digging.

 

Might still not be possible because I've a suspicion that the sewer pipe heads in that direction.

 

 

[Enterprisingwestern]

 

 

Mike.

[chris p bacon]

8 hours ago, Reorte said:

Presumably the tell tale strip is something obvious that you hit before the cable to warn you it's there when you're digging.

 

I should have put 'Warning tape'  such as this

 

https://www.tlc-direct.co.uk/Main_Index/Necessities_Index/Electric_Cable_Below_Tape/index.html

 

You can get much shorter lengths or put it in a metal pipe to protect it from spades etc