Hi All, Our garage is at the bottom of the garden, there is currently a 20A feed to it made up of twin and earth in the house then connected to SWA for the outside run. We're thinking of getting wooden floors laid in the not too distant future, so I'm thinking about getting the feed upgraded to the garage. I don't need more than 20A at present, however I am thinking in terms of future proofing for having an electric car charger there. It's likely that one of the cars will be fully electric when they come up for replacement. Question is what size cable to go for? Should I max it out so that what is installed is plenty for say 63A all the way through. or just deal with the indoor section and tackle the outdoor later? I'll not be doing the work, but I'll be doing all the furniture shifting for access.
some fast chargers need three phase! always go for the largest supply as the amount of work / labour does not alter with wire size.
What’s the run length? That may ultimately determine what you can draw. Cost may also become a factor unless of course you know someone that can get you a decent price on the cable. I wouldn’t waste my time upgrading part, just do the lot then it’s done, especially if your planning on spending years at your current property. But as above, go for the biggest you can afford
6mm SWA is good for up to 40 amps, my sparky told me, so you should go for 10mm, or bigger. Plus the length makes a difference to how much power you can get down it.
Go big, or go home. I sat down with my sparky, he reckoned 6mm would just bout do, so go for 10. I priced it up and it was not much between 10 and 16, so I went for 16. I did the grunt work, ran and clipped the cable, dug the trench, holes in walls etc etc. He came and checked it out and I back filled the trench. He then supplied the DB which has 4 slots plus the main breaker, and wired it all in. I think I got change from £200 for his bit and the SWA was a bit less than that
I have a 10mm SWA cable running from a 50A MCB in the main CU in the house to a CU in my workshop some 20m away. The cable run is probably near to 25m. It runs underground all the way and according to the tables that works out to just under 7.5v drop at the cable rating of 67A (well within 4%). That is of course, assuming I can read and have done my sums right. Neither of these is guaranteed! I've yet to trip anything either in the house or the workshop (not by accident that is!) so it can't be too far out. BTW, my recommendation, definitely do the whole thing at the one go.
Also if your trenching then it’s good to stick a cat5 cable in as well. I have wired internet out here and it’s handy.
Yeah, I got that too! Two of them actually, and it came in quite handy when lockdown started and I had to work from home. It meant I could plug my work laptop in and still have my home computer connected too. Mind you, my back drop got a bit of envy amongst the office staff! Beats a wall full of unread books
Cheers all. There is already ducting in place for the existing feed. Hopefully should be able to draw through that. The main prompter has been the solid wood flooring as once that's down I don't want to have to lift it. Makes sense to go as big as possible. Time to phone the sparkey.
Probably not. It isn't at present. It would also be a bit of a pig to get it there. What are you thinking?
your only other option is use flat twin and earth in the house and a weatherproof joint on the outside wall of house and finish off with the armoured . makes no odds which
I managed to get my 3 core 35mm armoured in to the house and sunk it in the wall up under the floor and put a joint inside then 10.0mm flat to the db reason cable was so big I nicked a big length from a factory that went bankrupt it was left outside next to where I was working
bet you got a sweat on doing that, I work with the sparkies pulling cables when I want to remind myself what hard work is.
there was 35 meters just layed outside. 2 of us rolled it up and took 4 of us to put it on the van roof rack
I ran my SWA to just inside the garage, then a junction box, to use T & E to the consumer unit. That saved having a waterproof connection out in the back yard.
Got lumbered into running cables on the site of the new waste water works in Grangemouth in Scotland years ago, we only did half a day and i was cream-krackered after it, some of it must have been 30mm in diameter, and bloody heavy.
