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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
    wallywombat:

    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.


    What about diversity? If everybody charges slowly at the same time, there is none; but if cars are charged quickly quite a lot of diversity could be applied. Granted we might all try to travel at the same time, but that doesn't mean that we would all plug in at the same time.


    I don't know how far the average car commute is, but 20 miles is more than enough for me. That's 10 kWh (for both ways) or about an hour and a half on a 7 kW EVCP.


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  • 0
    wallywombat:

    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.


    What about diversity? If everybody charges slowly at the same time, there is none; but if cars are charged quickly quite a lot of diversity could be applied. Granted we might all try to travel at the same time, but that doesn't mean that we would all plug in at the same time.


    I don't know how far the average car commute is, but 20 miles is more than enough for me. That's 10 kWh (for both ways) or about an hour and a half on a 7 kW EVCP.


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