External Garage - Charging

[NastyNick83]

Don't be surprised if it's just a normal ring main cable in a plastic pipe - what I found installed between our house and garage!! (No idea who installed that 35 years ago!)

Worse of all it wasn't even a single plastic pipe, it was in sections and ended up having to dig a trench to find the damn thing which of course took a random, non-direct path across the garden - since it proved impossible to just pull the new cable through with the old!

The end result is I have new cable running from house box to garage where it terminates in a fuse box (breakers) and then on to the lights, sockets and car chargers.

I shall look forward to what I discover when we move in!

Assuming it's still 2.5mm then there wouldn't be a need to replace it (just not armoured SWA)? Were you able to pull the cable through or did you have to dig it all out?

Nick

 

[Glan gluaisne]

The garage in our old house just had a 2.5mm² run of T&E inside a length of 15mm copper water pipe to protect it. It was only a short overhead run across a path between the house and the garage, though, and was a perfectly OK way of doing it. Whoever had done it had done a decent job, with a bonding wire and clamp to the copper pipe. Seemed a good solution for an overhead run of around 2m or so.

 

[NastyNick83]

Because this is an existing circuit, and all you're doing is changing things at the ends of it, then there's no legal requirement for another Part P EIC to be lodged. The same applies to any changes to existing circuits, and is worth knowing, as it can make things a lot easier with a bit of careful planning.

I'm not Part P registered, only because none of the Part P cartels will accept someone that's competent, but retired, as a member any more (which pretty much proves they are really about protectionism and making money!). When we built our house I had to get a Part P chap to sign it off, because of that. In theory building control are supposed to be able to sign off third party work, but in practice the Part P cartels are reluctant to grant third party sign off rights to members, so it's rare to find a BC dept that can do it. The way I future proofed things, was to add several cable runs, mostly ducted runs of SWA, terminated in wiska boxes, with nothing connected to them. They were all on the EIC and duly tested and signed off against Part P, so I've then been able to add stuff outdoors, like CCTV supplies, garden lights, power to a shed, etc, without breaching any regs, as I've only been changing the ends of existing approved circuits.

Presumably the difference with a new car charger is it's a new cable/run from the CU so classed as a new circuit? And it's a 32A (or in my case 16A) going out to a metal object so they're being extra cautious.

All food for thought!

Thanks again!

Nick

 

[Glan gluaisne]

Presumably the difference with a new car charger is it's a new cable/run from the CU so classed as a new circuit? And it's a 32A (or in my case 16A) going out to a metal object so they're being extra cautious.

All food for thought!

Thanks again!

Nick

Yes, that's it. Any new circuit that's outdoors, or in a few other special locations, has to have a Part P ticket (unless you're in Scotland, where Part P doesn't exist). In this case the garage circuit already exists, so any changes to the ends of it don't require another Part P chit.

Part P also applies to new circuits in places like bathrooms, but it's OK to run a new circuit to, say, a living room, without needing a Part P chit (still have to comply with the regs, but that's all).

 

[Alistairuk]

I shall look forward to what I discover when we move in!

Assuming it's still 2.5mm then there wouldn't be a need to replace it (just not armoured SWA)? Were you able to pull the cable through or did you have to dig it all out?

Nick

Ended up digging it all up as the cable kept jamming every meter or so when trying to pull it through as the pipe was not a single piece.

 

[pgkevet]

There may be no-dig solutions depending on shape of buildings and relationship. Here my car is in the barn some 50yds from thehouse with armoured cable tied to an overhead wire - high enough to get a trailer of bales under it. When my dad built his house he put a pergola between house and garage and ran the wire on that.

 

[Glan gluaisne]

You can also hire a mole, but you need a big compressor to drive a pneumatic one, plus a bit of skill in lining it up in the starter hole. Rather than hire and DIY, I opted to get a moling chap in, definitely the best solution. I dug the start and end pits, he turned up, lined up the mole and had the job finished in a couple of hours, including pulling the cable through for me. That was going under a concrete farm yard, perhaps 15m wide. Only issues with moling are that you need to know whether there are any services in the vicinity and they aren't a great solution in rocky ground. Other than that they are probably the cheapest and easiest way to get cables under surfaces you don't want to dig up.

 

[j1mgg]

Our house was built in 2004 and has a detached garage supplied with electricity. I only had to get e new fuse box in the garage, only had two slots, and I needed a extra for the car charger.

I am getting the quoted 7kw.

 

[Adopado]

I am getting the quoted 7kw.

At the end of the day they all broadly do the same job and, unless actually faulty, charge at the same rates. You pay for some different features and for the appearance and perhaps the general quality of the housing.

 

[Glan gluaisne]

Our house was built in 2004 and has a detached garage supplied with electricity. I only had to get e new fuse box in the garage, only had two slots, and I needed a extra for the car charger.

I am getting the quoted 7kw.

This all depends on whether or not the cable to the garage was conservatively sized or not when the house was built. In the overall scheme of things the cost of the cable isn't significant, and in a perfect world all houses would be built with over-sized cables, so that additional loads could be added without major disruption. However, it seems very common for new houses to be built with only a 2.5mm² cable supplying the garage, and that then limits the maximum allowable current from a charge point to about 16 A or so, perhaps 20 A at a push.

Presumably you were lucky enough to have a 6mm² supply to the garage, which is pretty unusual, but, TBH, might only have added around £10 or £20 to the cost of the original installation. Be nice if more builders included provision like this in new houses, although I believe that there is now a recommendation to include provision for installing a charge point without major new works in all new houses, which could probably be met by just uprating the cable feeding the garage.

Presumably along with the additional MCB you also had the mandatory additional protection installed on the garage circuit? For a detached garage this may mean changing the whole garage to a TT installation, to comply with the mandatory requirement that there shall not be two different earthing systems within touching distance of each other.