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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



    What colour is the existing cut-out, grey or black?


    Regards


    BOD


    Black


  • 0
    Bad choice ?

    https://www.energynetworks.org/industry-hub/resource-library/low-carbon-technologies-cut-out-rating-guidance-to-electric-vehicle-or-heat-pump-installers.pdf
  • Former Community Member
    0 Former Community Member
    I agree, the black ones are only rated at 80 A by the DNO so if you ask for 81 A, it will trigger the need to change it to the newer DMC type that are rated at 100 A by the DNO. This in turn will trigger network involvement and possibly reinforcement at consumer's cost as the standard supply is typically 15 kVA for domestic.


    Regards


    BOD
  • 0
    perspicacious:

    I agree, the black ones are only rated at 80 A by the DNO so if you ask for 81 A, it will trigger the need to change it to the newer DMC type that are rated at 100 A by the DNO. This in turn will trigger network involvement and possibly reinforcement at consumer's cost as the standard supply is typically 15 kVA for domestic.


    Regards


    BOD


    It all started as I was taught to ask for upgrade to 100A if installing EVSE. This would just involve upgrading meter tails to 25mm. This by the way has been done already and a smart meter fitted. I’m guessing if the cut out has been upgraded it would have been appropriately labelled...


  • Former Community Member
    0 Former Community Member
    Good document there Andy, I was only going by "experience", not something documented like that pdf.


    Not good bedtime reading for the OP though................


    Regards


    BED
  • 0
    perspicacious:

    Good document there Andy, I was only going by "experience", not something documented like that pdf.


    Not good bedtime reading for the OP though................


    Regards


    BED


    Fortunately I’ve read that before!


  • Former Community Member
    0 Former Community Member
    Just one more thing [(c) Columbo]


    What is the Ze at the cut-out?


    Regards


    BED
  • 0
    perspicacious:

    Just one more thing [(c) Columbo]


    What is the Ze at the cut-out?


    Regards


    BED


    I haven’t measured it yet, I would hope it was in spec...


  • 0
    Black cutouts can be fitted with 100 amp fuses the one here is I've seen the fuse when the DNO came to re attach a loose earth cable.
  • 0
    Returning to the O/P, I suppose an optimist might assume that if the existing cut out fuse has never operated, that the addition of an EV charger WITH LOAD LIMITING  will not increase the risk of the fuse operating since the maximum demand is not increased.


    I do perceive a slightly increased risk of the fuse operating since it may be run for hours at full load, IN ADDITION to the odd short term overload.


    The wider issues are interesting, but frankly are the worry of the DNO and not the consumer.


    As EVs become popular, I suspect that most will be charged either at night, on off peak tariffs, when wind power is a larger percentage of demand, or perhaps at work places during working hours when PV is more plentiful.

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