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Connecting Multiple Bemco/Ryefield Boards

GHEC
Ok I have a new build project where one Bemco/Ryefield board is not large enough to cover all apartments. 


I will need to install 3 to cover the number of outgoing ways required.


My questions is this. Given that there is one incoming bulk supply, what options are there to split it between the three? I know Lucy do an MSDB with a vertical busbar. Would the DNO accept daisy chaining these together? Or should we use a busbar chamber and tap-off to each board?


Any advice would be gratefully received.
  • 0

    Engineer01:

    Hi Gareth,


    On larger developments which require more than 1 Ryefield board you would simply supply them from a Schneider "mode" board or similar, this allows each Ryefield to be unmetered to allow the apartments to get their own MPAN numbers.


    Substation supply to MODE usually 400A - Mode to BEMCO usually 200A per phase each via 95mm 4Core. This is pretty standard IDNO / BNO arrangement and standard sizes.


    If you have one incoming supply at present youll want the DNO/IDNO to modify the supply arrangement to serve the MODE board first to allow unmetered supplies to be taken from it. 


    The landlord supply can then either be taken from from one of the BEMCO boards if MD is under 70KVA or taken direct from MODE if you require greater.  


    I wouldnt recommend supplying any apartment from landlords supplies due to tenants rights to be able to switch energy supplier should they wish. With supply from landlords supply they will be responsible for sourcing energy supplier and would have to sell the electric back to tenants for no profit.   


    Hope thats useful and makes sense. 

     







    Hi Engineer01


    I wasn't aware of the Schneider Mode boards. Just had a look. 


    Makes perfect sense thanks. 

  • 0
    I have designed quite a few blocks of flats from low rise up to 2 x 40 story modular builds.


    How many flats per floor and how many floors. Anything else to be. Supplied such as gym, laundry, shops etc?
  • 0

    John Peckham:

    I have designed quite a few blocks of flats from low rise up to 2 x 40 story modular builds.


    How many flats per floor and how many floors. Anything else to be. Supplied such as gym, laundry, shops etc?




    Hi John,


    Have you ever come across a block of flats which are served from a rising busbar to the BEMCO's? 


    Whats your typical supplying arrangement / metering strategy out of curiosity? 


    Just interested to see how others design large resi jobs. 

  • 0
    Yes for taller blocks Zuccini bus bars, tenants bus bar on one side of the riser and the landlords on the other side. LSS in the corner of the mechanical riser to upset the plumbers.
  • 0
    Thanks for confirming, I have seen this on a few jobs recently.


    I personally have never designed them in this way, as i understand it this would mean the tenants are unable to switch meter supplier?


    Ive always gone for a completely unmetered supply for tenants (via mode and bemco board) and dedicated metered supplies for landlord. 

  • 0
    The tenants bus bar is part of the un-metered BNO network. The supplies to the Ryfield boards are taken from tap off boxes on the BNO bus bar. Each flat supply comes from a fuse in the Ryfield to a Series 8 head fitted with a " Red Head" solid link for meter isolation to the meter and then a switch fuse. The meters are in the riser cupboard on each floor that the flats are on. SWA cable from switch fuse to the consumer unit in the flats.

  • 0
    Just noticed that your job is 3 phase to each flat for electric heating. Not done one of those. I would still do it the same way but 3 phase. One of the requirents is the option to change the credit meter for a key meter, I have not seen a 3 phase key meter?
  • 0
    The schematics for 3 phase (or indeed split phase) prepayment metering that I have seen are a bit like This thing    

    basically the card reader part's gated output operates a singe phase contactor coil with a contact per phase to cut the power to the loads, and the 3 phase metering, which may be whole current or based on CTs creates a pulse count type output that feeds into the card reader part. (pulses being the standard LED flash of nominal 80msec long, and 1600 per kwh, or  a pulse every 2250 watt seconds)

    The whole thing is then boxed up as an  anti tamper  sealed assembly.

    An example of the kit of parts is   here  I have not seen it in the wild, but we were once asked to look at the feasibility of a system like this for someone, it is not cheap, but it can be done.
  • 0

    John Peckham:

    The tenants bus bar is part of the un-metered BNO network. The supplies to the Ryfield boards are taken from tap off boxes on the BNO bus bar. Each flat supply comes from a fuse in the Ryfield to a Series 8 head fitted with a " Red Head" solid link for meter isolation to the meter and then a switch fuse. The meters are in the riser cupboard on each floor that the flats are on. SWA cable from switch fuse to the consumer unit in the flats.

     




    Thanks John. How is the busbar served, via LV Switchboard & MCCB? id have thought it would need to be metered, otherwise whats to stop someone putting a tap off onto the busbar and taking themselves an unmetered supply or taking a supply from the switchboard? 

  • 0
    The BNO network is un-metered and it is one of the jobs on the BNO to prevent abstraction by restricting access and locking the Ryfield boards.


    The bigger jobs I have designed using bus bars have been supplied straight from a transformer in AWAs to a panel board with MCCBs protecting SWAs to the end feed units on the bus bars. The supply to the landlords bus bar is metered.

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