Wiring in an electric car charging point

Yes, sounds easiest provided getting the cable back to the garage from the CU isn't too tortuous ...

If needed you could put a small CU after the 63A breaker

You really *don’t* want to have your EV charger wired into your main consumer unit. If you do this, and then you (or your house buyer) goes for a solar/battery system you’ll need to redo it if you want to avoid discharging your home battery into your car when charging.

Yea, there are a number of workarounds but by far the simplest is to have your inverter CT clamp in a position where it can’t sense power drawn by your EV charger. This is much easier to arrange if your Eva charger has its own dedicated consumer unit.

Tim

You can put it inside the CU but it'll be limited by the overall 63A breaker. If you'd prefer it in the CU I'd look to upgrade the breaker, assuming the wiring from there to the CU is big enough.

What other loads do you have? Any ASHPs, electric showers or anything that takes a lot of current? How many ring mains?

Your options are:

- tee off and add a mini CU in the garage - before the breaker. Shouldn't have any problems with exceeding the 100A supply

- tee off after the breaker but be limited to 63A total

- replace the breaker - if the wiring to the house CU can't handle 100A you can still tee off at the breaker and get 63+32A via a new 100A breaker.

- replace the breaker and/or wiring to CU, make sure CU breaker is 100A and take from CU

- throttle the car demand. At 4miles/kWh a 32A charger is putting on 128miles/hour. Many people don't need this kind of charging speed because they only do a few dozen miles a day so 16A or less charging is fine. OTOH a high charging speed is better to make use of night tariffs that give you cheap 4/5h.

I'd decide what you actually need in terms of charging current and work back from there.

Look at 'intelligent' tariffs like Intelligent Octopus Go, where they need to talk to the charger to set your cheap rate. Decide if this is worth having, and if so fit one they support. Maybe not needed if they support talking to the car directly.

Also if you have or might have in future battery or solar, look for something that'll talk to that setup.

Otherwise they're much of a muchness. Chargers sold new have to be 'smart', used ones don't. You can sometimes pick up older non-smart used chargers for cheap on ebay - for the smart ones beware that you need to check the servers are still running and you don't need to be an official installer to re-register them.

Theo

Helpful, thanks.

It's a bit odd. The first video swears blind that RCD protection is not needed, and indeed there's a new consumer unit without RCD protection. The second video says that's all wrong.

So ...?

Is there any isolator before the 63A breaker, or *is* the breaker the only isolation between meter and existing CU? If the O/P is DIYing, is he comfortable pulling the main fuse?

There's no isolator before the 63A breaker.

Obviously make sure there's no current draw before pulling the fuse. The fuse was fitted last year, so it's not brittle plastic, and should be reasonably safe.

Depends what the "charger" includes, newer ones do their on PEN fault detection, older ones will require RCD ...

Should have got the DNO to fit an isolating switch at the same time.

Mmm. I'd be tempted to up that breaker to 100A and split off to a separate CU in the garage

I would. A lot more options that way.

I cant remember if you have to have a single 'whole house' breaker or not. My preference would be a 100A whole house breaker and then tee off to a new CU in the garage for that charger and any new garage circuits needed.

But installing a new main breaker is a bit hairy - you need to pull the company fuse for that.

Whatever fits the car?

The first (4 year old video) is talking about the "cable" not requiring protection not that the installation doesn't require protection. Also surge protection regulation seems to have changed.

...

In practice, with mine, I work on 25 miles/h.

nib

This is my understanding . The firm that installed solar panels, battery and charger for my daughter made this mistake.

It might be useful if the body of the car becomes mains live and you touch it.

Err. 32A only gives 32kW if you have a 1000v supply! For a 230v supply, it's about 7kW - or 28 miles/hour if you're lucky. My experience says that 4 miles/kWh is pretty optimistic. My VW ID3 has averaged under 3 miles/kWh over its 3-year life so far.

When my charger was installed 3+ years ago, you needed to apply to the DNO for permission to do so, and you had to submit details of all the circuits in the house so that they could evaluate whether the supply was adequate. In my case, they fitted a new head unit and upgraded the main fuse from 60A to 80A. [The incoming wiring wouldn't support 100A]

Do you not still have to do so?

Sorry, brain fart. I thought that figure was a bit high!

It depends on the vehicle - cars with good aero like Teslas approach

If you need less than 60A you don't need to notify the DNO after the fact but they don't need to approve it. If you need more than 60A you have to get the nod from the DNO first, in case they need to do any network work first. Most of the checks are automated nowadays:

(I got a smart meter fitted and Octopus upgraded the meter tails to 25mm2. I then contacted the DNO and they came out and switched the cutout to be

Theo

When I got my smart meter fitted via Octopus I also got upgraded meter tails (and an isolating switch) for free.