garage power, old house, help needed

Gents, im hoping for some help / advice, before i start i am not an electrician, i am a very competent diyer, however i have no interest in burning my house down! so i want advice so when i get some quotes in i know what to check the electrician for so i feel comfortable, i am not after any technical details but guidance please, i have searched though old posts, and got a general idea, but would like some help.

i have recently moved into a 1930's house where there is no power supply to the garage, however i would like one. The garage is watertight with no leaks, and is of concrete panel construction.

i have attached an image below of the layout, should the power be taken from the fusebox? one electrician i called in offered to take it from a plug in the kitchen, which seemed very dodgy to me, and duct the cables under my patio, and adding a fuseboc in the garage? The drainage in my garden is not too good, is it okay the cable will be essentially sitting in water?

also if the feed is taken from the fuse box do i have to chip up a line in the drive (which i would rather not do)? or can it be run along the house? if it did the feed would cross what appears to be the main earth from the electricity supply.

just so you are aware as i say i am confident at most diy tasks, but electricity is not something i want to have a go with, changing sockets im okay with, but im not attempting anything else, so id like to be in a position to know what someone is talking about before letting them work on my house

Any advice would be hugely appreciated.

thanks very much

A supply to an outside building can't just be attached to the circuit supplying sockets in the house, it needs its own dedicated supply.

Underground cable is OK. Infact most homes in the UK are supplied by underground cables. The cable has to be suitable for undergound use (steel wire armoured is the most common) and burried to the proper depth with warning tape above it.

Cables installed above ground need to be to the correct height and suitably supported, it can't simply be attached to a fence. In your example, it could be clipped direct to the wall of the house and then run overhead to the garage.

As a detached building your garage needs its own consumer unit for isolation and distribution with suitable MCB and RCD protection.

The sizes and ratings of the cables and MCB's will depend upon what you want to use the garage for.

What is your expected maximum demand for the garage.

If it is 13A or under then you can take a spur off a ring main to feed the garage, the only problem with this option is there is no way to upgrade when you find you need more capacity and you'll end up running a new circuit after all.

If you run conduit along your house you can run the cable in that to remove the need for digging up a concrete path, and it's going to be easy to upgrade at a later date.

Remember to get a sparky who is a member of a self-certification scheme as this work is notifiable.

thank you both very much for the reply, i understand the work is notifiable, in regard to demand, im thinking a couple of lights and a few power tools, maybe a small welder.

do both your replies contradict each other though? one says take a spur, one says don't, i would personally rather have a dedicated feed.

so in all i am best having a feed from the fusebox, run along the house in conduit, the span between the house and garage is fairly large - perhaps 5m, and i think a cable would sag, would it be best then running down the house to the ground and doing the last stretch underground, rather than an excessive span above ground?

thanks again

I didn't say 'take a spur' I said if your demand is below 13A you can take a spur, it is better to take a dedicated feed but if you know you won't ever need more than 13A it's overkill.

From your picture it looks like you can just take a straight run of conduit straight to the garage, no need for it to be suspended then.

ah right sorry davy, my misunderstanding.

The drawing isn't to scale, but im unsure how you mean by run the conduit, would it have to run at a certain height, and surely i couldn't run conduit to span the gap?

apologies if im misunderstanding.

thanks again

Sorry, I totally forgot about the patio.

Since you said you don't want to dig up the drive your only option is to run it overhead. 5m isn't a problem, but the cable will need to be suitable and will need support, but your sparky will ensure this.

thanks for all the advice, much appreciated