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Maximum Demand / ENA / EV Help!

D4G
Hello all,


This evenings issue relates to an EV charger install.

The supply cut out is labelled 60/80 amp so I called the DNO and asked if this could be uprated to 100 amp.

They have sent me the ENA EV application form which asks for the Maximum Demand including the new equipment.

The problem I have is the existing circuits are:


32A - 7.2 kW shower 

40A - 8.2 kW shower

32A - Ring main

32A - 7.9 kw cooker

6A - lighting

6A - lighting

6A - security


Additional 32A for EV charger


So even with diversity I'm way over 100A, obviously in reality the diversity calculations are not appropriate as the client has never blown the cut out.

The smaller shower is not currently in use although they want to replace it for another one, I have told them this may not be possible.

The EV charger will have load management but I still need to put a figure on the ENA form....


Help appriciated :)
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  • 0
    If you make the rough assumptions that the total mileage of each household is 10,000 miles per year and that EVs do about 5 miles per kWh, then the existing domestic infrastructure can just about cope as long as cars are given a slow 7 hour-ish charge each night when the local network would otherwise be mostly unused. That works out at about 3.5A per house.


    This does of course require smart chargers talking to smart meters so that the consumer plugs in their car when arriving home from work, and presses one of two buttons: (a) quick charge as I'm going out in half an hour or (b) please be fully charged by next morning. For (b) the smart charger needs to know not to come on until late evening, and not to immediately turn on full  like storage heaters, but to slowly charge, varying the exact rate according to feedback from the smart meter, and hence from the substation and ultimately from the national grid.


    As far as I'm aware, smart meters and chargers don't currently do this, and there doesn't seem to be any immediate plan to make it so.


    Also, I assume separately that 400kV pylons or similar will have to feed each motorway service station to provide the equivalent of 5-minute petrol station refills for many cars.
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  • 0
    If you make the rough assumptions that the total mileage of each household is 10,000 miles per year and that EVs do about 5 miles per kWh, then the existing domestic infrastructure can just about cope as long as cars are given a slow 7 hour-ish charge each night when the local network would otherwise be mostly unused. That works out at about 3.5A per house.


    This does of course require smart chargers talking to smart meters so that the consumer plugs in their car when arriving home from work, and presses one of two buttons: (a) quick charge as I'm going out in half an hour or (b) please be fully charged by next morning. For (b) the smart charger needs to know not to come on until late evening, and not to immediately turn on full  like storage heaters, but to slowly charge, varying the exact rate according to feedback from the smart meter, and hence from the substation and ultimately from the national grid.


    As far as I'm aware, smart meters and chargers don't currently do this, and there doesn't seem to be any immediate plan to make it so.


    Also, I assume separately that 400kV pylons or similar will have to feed each motorway service station to provide the equivalent of 5-minute petrol station refills for many cars.
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