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Topic Title: EV Charger
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Created On: 13 January 2018 02:30 PM
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 13 January 2018 02:30 PM
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Nospark

Posts: 197
Joined: 05 October 2013

What are the load characteristics of a 3.6kW EV charger? Near 16A for the duration of the charge?
I've been asked to upgrade a garage supply to accommodate one, and am facing demand and discrimination issues.
 13 January 2018 04:51 PM
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broadgage

Posts: 2489
Joined: 07 August 2007

Sounds borderline even on a 16 amp ceeform outlet.
You would probably get away with 2.5mm cable from a 16 amp MCB, into a 16 amp socket.
Borderline though if the charger is a constant wattage load and therefore consumes more amps at lower input voltages.

Allowing for the worst case
"3.6 kw" charger is in fact 3.7kw, due to manufacturing tolerances.
Mains voltage at the lower limit of 217 volts at the intake and perhaps 210 volts at the charger.
Imperfect power factor, modern chargers have a good power factor, but not perhaps unity. Allow say 5% for a good but not absolutely perfect power factor.

Better practice in my view would be a 32 amp ceeform outlet on 6mm cable.

What size is the service fuse, and is it heavily loaded already?
 13 January 2018 05:15 PM
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Nospark

Posts: 197
Joined: 05 October 2013

Don't know the service fuse size. Got a 100A label on it, but I don't take that as certain. Although its a newish build, about 10 years old. Currently the house has the following ccts: 32A-Cooker, 32A-Skts, 32A-Skts, 16A-Skts, 16A-Water heater, 16A-Garage, 4 x 6A Lights, 6A-Central Heating, 6A-Smoke Detectors. According to the OSG, that puts over 100A demand with diversity. I don't know the exact load of the cooker. They have a boiler for heating/hot water, so the water heater is an immersion. I feel fairly confident that the extra EV charger load won't be too much, water heater never used, sockets not any where near 32A in practice, but what do we put on the EIC for max demand..
Thing is, the garage is fed via a 2.5mm 3 core buried SWA. It is near impossible to run a new cable due to concrete floors and CU position. So if I upgrade the mcb supplying the garage to a 20A or 25A, discrimination will not be achieved. I don't like the idea of the rcd protection being in the CU as part of a split load CU. But in practice, is this really a concern? Even if I somehow manage to take the mcb supplying the garage of the rcd, and install a garage CU with rcd/rcbo's, discrimination will still not be achieved.
The EV installers have requested a B16A mcb with rcd.
In addition, house is tnc-s, tt garage needed, although it isn't at present.
 13 January 2018 06:53 PM
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AJJewsbury

Posts: 16208
Joined: 13 August 2003

Better practice in my view would be a 32 amp ceeform outlet on 6mm cable.

Isn't the usual these days to have a wall mounted "charging station" hard wired to the supply rather than industrial sockets? (this kind of thing: http://www.meteorelectrical.co...ixed-lead-t2-plug.html ) - so that the lead to the vehicle is protected (the charging station only energises its output once the car is connected and earth continuity is verified). I gather there's also some negotiation about charge rates between such equipment and the vehicle.
- Andy.
 13 January 2018 09:09 PM
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alancapon

Posts: 6986
Joined: 27 December 2005

I agree with Andy. You really shouldn't be fitting industrial sockets for EV charging points. The correct answer is a purpose made charging point with a "type 2" EV socket on it.

Regards,

Alan.
 15 January 2018 11:00 AM
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CMK3PD

Posts: 74
Joined: 23 September 2016

Mode 2 devices are still in use, those are fed from a "standard socket-outlet" at anything up to 32A single or three phase. However to be fair I would prefer to have a compliant purpose made point fitted as suggested. You can get a grant for those too, whereas you won't get a grant for fitting a socket in the garage.
 15 January 2018 11:19 AM
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alancapon

Posts: 6986
Joined: 27 December 2005

I agree that there are still Mode 2 devices in use, but most of these vehicles also come with the standard cable with a "type 2" plug as well.

Regards,

Alan.
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