Hi,

We’re moving in August and the new house has a stone outbuilding at the top of the garden which is about 18 feet from the back door. The consumer unit/junction box is in the front of the house. Any ideas what this entails and rough costs? I’ll get a sparky in once we move for a proper quote, but after a rough idea in the meantime.

Thanks.

No idea on cost but you would need to run an armoured cable in some ducting along the side of the house and then underground into the outbuilding….. You may need a small consumer unit in the outbuilding also.
If you ran the cabling yourself you could just use the sparky to make the connections thus reducing your costs.
It sort of depends on what you want to power in the outbuilding – just lights or heater, kettle, welder, …….

Thanks. Would want a couple of strip lights inside and a couple of sockets, plus an outside light and an outside socket. The most I would be using would be a drill, soldering iron etc so nothing of any significant load.

6mm armoured over that distance, no need for ducting. Decent garage/shed consumer unit at the other end. As above connections at both ends can be done by a sparks easily in a coupla hrs. Just make sure you have an existing spare way in your house consumer unit as it would be preferable to feed it individually.

I used a kit from B&Q when I put power into the shed. The kit includes everything to do it yourself and there’s no need for an electrician as it just plugs into a normal socket in the house with a rcd adapter. Involves a bit of drilling through the walls but easy enough. Will take up to 13 amps so should be ok for your needs. Think it was only £80 ish for the kit.

I used a kit from B&Q when I put power into the shed. The kit includes everything to do it yourself and there’s no need for an electrician as it just plugs into a normal socket in the house with a rcd adapter. Involves a bit of drilling through the walls but easy enough. Will take up to 13 amps so should be ok for your needs. Think it was only £80 ish for the kit.

Thanks. Not sure how this affects building regs as I read that as soon as something becomes ‘fixed’ it is then subject to inspection by the planning people? Did you have to bury the cable that was included in the kit?

6mm armoured over that distance, no need for ducting

You sure about no ducting? I thought you needed to run the armoured through some PVC pipe. Either way if your digging a trench for the cable you may as well put it in a couple of quids worth of duct for the extra protection.

Na not needed

Yeah had to dig a foot deep trench for the armoured cable. Not sure about inspections and planning regs but cant imagine you would need it, or just dont tell anyone !

6mm cable for maybe 40 feet of circuit?
I’d say 2.5mm would be fine – what is the expected load? – typically the biggest current drawer would be a lawnmower at 1.5kW, so no need for a bigger cable, for either current consumption, or voltage drop.

No, you would not need any ducting if you use armoured (SWA) cable. to comply with the Regs, it will have to be RCD protected, either at the shed end, or from the consumer unit, entirely up to you how that is done. It does need Part P certification. This is regularly ignored, with no real penalty if you do DIY.
The cable should be buried to a depth that it is not going to be damaged in normal use i.e., at least deeper than a spade if it crosses a garden, preferably 600mm deep. If under a footpath/slabs, then a few inches would be sufficient, as it is protected from mechanical damage by the slabs.It should have a warning tape laid above it.
Price – MCB, or RCBO in CU, £3 – 20, cable ~ £1.50/m , CU in shed £20,fittings in shed £20-50, labour, £100ish, probably 3 hours work, without digging the trench, so around £250 I reckon.
If you’d like any more info, then please let me know.

Thanks Alan, that helps enormously.

Like what Alan has said there 🙂 but I will disagree on the SWA cabling.

2.5mm would be fine for the proposed load but if you’re going to wire stuff up, why not go a bit overboard and put something in with a higher rating?

Who’s to say you won’t want to run more stuff in the outbuilding in the future, which could mean having to redo it?

Just a thought

Oh and here’s a useful guide

Thats why I said 6 mm, it will cover most options easily and as I’m sure you know, once man has power, man plug everything into cave!! Plus we always have loads of 6mm knocking about on site!

And no you don’t need duct, it offers no more protection against a spade edge than the swa!! And seriously who puts warning tape up the garden??

You put warning tape 6 inch above the cable in the trench.

According to Western Power Distribution who wanted to run two cables under our garden to feed two houses (via wayleave) their plan was to bury a non armoured cable approx 40cm deep using a mole, and that was all, no duct, no armour. We have declined. But apparently it must meet regs (unlike the uncovered live cable 10′ off the ground that crossed our garden!!!)

Beaware that there may well be a sewer going across the garden, also water and gas pipes, not all are fed from the front of house.

A roll of electric caution tape is a few quid, and may well save someones life if they put a spade through it.

Armoured cable has stands of steel wound around the internal wires and is coated with a strong PVC jacket, not to mention the Earth Live and Neutral will have a nice PVC jacket too so ithink its safe to say you don’t need to run it through any trunking.

It is notifiable to Building control but most people ignore this and given it’s your house, no one need know! unless you come to sell then you just take out an indemnity policy to cover the fact you don’t have it signed off by BC or a Part P registered Sparky which would cost you A LOT more than the indemnity policy!

swa in side conduit, inside water pipe, vacuum sealed. berried to a depth of 3 m with with visual and audible warnings that them self have a automatic back up power supply of either battery or generator suitable of supply power to warnings for at least one week.

😆