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We've ordered two electric vehicles, and we're entitled to two home charge points, as shown here:

https://www.britishgas.co.uk/energy-saving-products/electric-vehicles

The charge points are now 7kw/32amp (up from 3kw/16amp), so if we have two in use at the same time, that's 64amps!(?).

When I spoke to British Gas, they said 2x7kw chargers should be fine if we have "two 100amp isolators", and if we don't, this is something that could be done (at a price) and I should speak to an electrician.

Before I do, I want to make sure I understand exactly what's required.. By "two 100amp isolators" I presume he's referring to the things we have two of here marked "RCD Controlled Circuits" (both rated 80amp).

Consumer Unit

Totals for the two sides here are:

  • Left: 6+6+16+32 = 60amps
  • Right: 6+16+32+32 = 86amps

"Water Heater" presumably refers to the immersion heater that will hopefully never need to be used. We have no electric shower. Oven ("Cooker", 32amp) is electric though hobs are gas.

What's the best way we can connect two 32amp EV chargers here?

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The most important thing to check is probably the size of the main supply fuse on your incoming feed. Between 60 and 100 amps is typical for a domestic supply. If you have a 60 amp fuse, I'd be very wary of trying to run two chargers at 7KW each simultaneously.

The other thing to consider is the actual consumption of the chargers that will be connected. Just because the supply point is rated to 7KW, doesn't mean that the charger will actually draw that.

You don't need to accommodate the full current capacity of all the breakers because you're unlikely to be using everything that you possibly can at any one time, but if your peak load exceed the main fuse, you have a problem.

Personally, I'd be very tempted to have nothing further to do with British Gas and approach a local electrician about the work. If their electrical work is priced like their plumbing, it'll be very expensive. (And I wouldn't be surprised if they subcontract it out anyway).

  • British Gas are fitting the chargers (I have no choice in this, the chargers are funded by the Gov't and Renault picked British Gas to supply them). The chargers will likely draw 32amps while charging, and could both by in use in the evening (at the same time as the 32amp oven), so obviously this makes me a little nervous. It's possible we could live with just one charger (given it's 4hr full charge, and my wife will only need to charge around once per fortnight!). Will check the fuse on the incoming feed by the meter, didn't realise there would be one there! – Danny Tuppeny Feb 20 '15 at 9:01
  • Actually, it's unlikely that the oven draws anything close to 32A. Probably more like 13A (some ovens come with a standard plug) - you'd need to check the power rating of the oven to be sure. A large cooker circuit is only usually actually needed when you have an electric hob. – John Feb 20 '15 at 13:58
  • You're right; the oven says 4.1kw (18 amps?). The fuse in the meter cupboard is only 100amps, so I guess adding 64amps of charging both cars (I do suspect they'll draw close to that) is pushing it. We'll just stick with one charger for now instead. Thanks! – Danny Tuppeny Feb 20 '15 at 17:47
  • @Dannytuppeny I would still get them both installed while the government is footing most of the bill. You might be able to use them both at the same time, you might not. But if you are getting them both cheap, at least you have a spare if one breaks, and you have the option of upgrading your electrical service later to handle both. – Grant Feb 22 '15 at 1:21
  • @Grant I doubt they'll install a second if it doesn't look like we'd comfortably be able to use it. We've thought about it lots, but with the wife's usage, it just doesn't really seem worthwhile. We're trying to get a 3-pin cable from Renault instead, which we can use in emergencies both at home, and away (usually £495!!). – Danny Tuppeny Feb 22 '15 at 9:12

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