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16mm tails 100A fuse - EV & ESS

vantech

Hi all,

Just looking for a quick sense check.

I currently have job with a 100A DNO fuse with 25mm meter tails feeding the main consumer unit. I’m planning to install an additional external consumer unit via a Henley block to supply:

  • 7kW EV charger
  • 5kW battery storage system (charging) plus 5kW backup circuit (discharge capability) - total 10kW. 

Due to routing constraints, installing 25mm tails to the external CU will be very difficult, so I’m considering using 16mm² tails instead.

The maximum potential simultaneous load on these tails would be approximately 74A (5kW charge + 5kW discharge + 7kW EV). The EV has a 60A load curtailment so the maximum is likely never going to be this high, and the backup circuit on the ESS is supplying sockets (excluding kitchen) and lights, so unlikely ever going to be more than 2-3kW. 

Given that the load is effectively limited by the connected equipment, would 16mm² tails be acceptable on a 100A supply in this scenario, or would 25mm tails be required?

Appreciate any guidance or references to regs / best practice.

Thanks.

Parents
  • 0

    Just reading  this  sorry if I have missed information.

    Presumably both the solar and esss can export to the grid, will dno require this to be limited and how is it going to be achieved with two inverters. Seems to be much more export capacity than is normally approved.

    Would it be simpler to have a hybrid inverter with solar and essential on same inverter, makes export easier to manage and if limited to say 25a output resuce max supply to cu1 atom some extent.

    Cu1 can then either be protected by switched fuse or a unit rated at 125a used. 125a units are available from the likes of schneider  although price at least doubles and space required increases by at least 50 percent. I considered this for one of my projects but going with a switched fuse to.protect the cu to keep costs down.

    Personally would avoid trusting user not to.play with max demand settings on ev charger  way to easy to change. Although I have done it with garage submains.

Reply
  • 0

    Just reading  this  sorry if I have missed information.

    Presumably both the solar and esss can export to the grid, will dno require this to be limited and how is it going to be achieved with two inverters. Seems to be much more export capacity than is normally approved.

    Would it be simpler to have a hybrid inverter with solar and essential on same inverter, makes export easier to manage and if limited to say 25a output resuce max supply to cu1 atom some extent.

    Cu1 can then either be protected by switched fuse or a unit rated at 125a used. 125a units are available from the likes of schneider  although price at least doubles and space required increases by at least 50 percent. I considered this for one of my projects but going with a switched fuse to.protect the cu to keep costs down.

    Personally would avoid trusting user not to.play with max demand settings on ev charger  way to easy to change. Although I have done it with garage submains.

Children
  • 0 in reply to Alan B

    Hi, 

    No problem, thanks for the reply. 

    The DNO has approved a 5kW export and there is a G100 compliant scheme installed.

    I have decided on an 80A upstream fuse for CU1 and calculated the CU2 for the EV/ESS cannot go beyond 100A in any scenario. 


    Thanks. 

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