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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 :)
  • 0
    well if the old cut out was 60 amps and has never blown, add on your 32A and ask for 92. If you ask for 81 or more they will fit a 100A fuse, which is what you want them to do.

    M.


    (do not worry the substation that supplies the street will be sized on something like 8 amps per house and they won't be changing it just for you.)
  • 0
    Well, I imagine that you could put the dinner in the oven whilst taking a shower with a heater in the bathroom and the car is still charging. Forget the size of the fuse, what is the ADMD agreed (contracted) with the DNO?


    In this area, I understand that 18 kVA is the norm.
  • 0
    The straight answer is you cannot have the EVSE without load management to turn it off whilst the other appliances are in use or you pay for a new three phase supply.
  • 0
    Thats the problem, It could be a 60 or 80 amp or even already been replaced with 100a and just not marked up!

    I know there is no issue as what I am adding has load management but just wondered what to put on the form....


    Thanks for you input, sounds sensible :)
  • 0
    Agreed but I still need to put a number on the form though??
  • 0
    The client may find that they can't operate two electric showers simultaneously anyway due to water pressure issues.
  • 0
    wallywombat:

    The client may find that they can't operate two electric showers simultaneously anyway due to water pressure issues.


    Didn't think of it that way!

    Just been looking at priority units so may suggest one anyway..


  • 0
    Still need to put a figure in that box though!
  • 0
    Whatever you put in the box will be unrealistic
  • 0
    Having Googled the question, I see the problem. If it is maximum demand, there is possibly a problem; but if it is after diversity maximum demand, possibly not.


    On the face of it, you have a problem because you have revealed your intention to install an EVCP, rather than just doing it. Good for you!


    I think that you need to clarify with the DNO whether they want to know your peak maximum demand or ADMD.


    Quite how you work out ADMD is for those in here who are cleverer than I. Even if you have an ADMD of 18 kVA, if that is your average consumption, the leccy bill will be eye-watering.

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