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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
    It will not be the DNO ADMD - that is pretty much the one that matches the leccy bill and is the 1 to 2kw or whatever that the load averages out to smoothed over a few days.

    They want max demand - in  the sense that this is the current that may flow for up to half an hour or so when the worst reasonably credible combination of loads is in use, so they can set their fuse and tails side accordingly, and also so they can panic when more than a certain fraction of houses on the same substation request a similar supply upgrade.

    Is the form asking for amps, or kVA ?


    Or you could turn on all the lights and run the showers and put a few rings on the cooker,  and stick a clamp meter over the live meter tail.

    The thing to realise is that the on-site guide approach to diversity is not really the right thing for this purpose.

    M.
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  • 0
    It will not be the DNO ADMD - that is pretty much the one that matches the leccy bill and is the 1 to 2kw or whatever that the load averages out to smoothed over a few days.

    They want max demand - in  the sense that this is the current that may flow for up to half an hour or so when the worst reasonably credible combination of loads is in use, so they can set their fuse and tails side accordingly, and also so they can panic when more than a certain fraction of houses on the same substation request a similar supply upgrade.

    Is the form asking for amps, or kVA ?


    Or you could turn on all the lights and run the showers and put a few rings on the cooker,  and stick a clamp meter over the live meter tail.

    The thing to realise is that the on-site guide approach to diversity is not really the right thing for this purpose.

    M.
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