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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
    The maximum demand situation is an absolute mess at the moment. I adopt the view taken by Jon Steward. My nett increase is zero as I only use EVSE with load curtailment.  I make my assessment of each situation based on the ENA cut out guidance and whether there are any combustible items stored within the immediate area. If I feel a safe install can proceed, I install and notify the DNO afterwards. I make it abundantly clear to the customer that the DNO may require upgrade not because of the additional EVSE but because their MD was theoretically already in excess of the supply capacity. 

    I have been asked on occasion by the DNO (NIE) to advise if the load curtailment is fail safe, ie. that the charge current will be switched off in the event of any failure of the load monitoring circuit. I use the Myenergi Zappi for domestic installs so I simply sent the DNO their answer to that. I have had no response and that was at least 6months ago.

    We all must make sure our installations are safe but the burden of supply capacity has to be borne by the DNOs who can in turn deal directly with any agitation from their customers!


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  • 0
    The maximum demand situation is an absolute mess at the moment. I adopt the view taken by Jon Steward. My nett increase is zero as I only use EVSE with load curtailment.  I make my assessment of each situation based on the ENA cut out guidance and whether there are any combustible items stored within the immediate area. If I feel a safe install can proceed, I install and notify the DNO afterwards. I make it abundantly clear to the customer that the DNO may require upgrade not because of the additional EVSE but because their MD was theoretically already in excess of the supply capacity. 

    I have been asked on occasion by the DNO (NIE) to advise if the load curtailment is fail safe, ie. that the charge current will be switched off in the event of any failure of the load monitoring circuit. I use the Myenergi Zappi for domestic installs so I simply sent the DNO their answer to that. I have had no response and that was at least 6months ago.

    We all must make sure our installations are safe but the burden of supply capacity has to be borne by the DNOs who can in turn deal directly with any agitation from their customers!


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