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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
    Hi everyone


    thank you for your answers. All very much appreciated. I think first and foremost, I will need to speak to the DNO in order to get their opinion. 


    To shed a bit more light on the project, this is a little different to most. There are only 35 flats, but they will be all electric in terms of cooking and heating. To add a twist, they are all being fitted with 24kW 3-phase electric water heaters.


    As a result, we need to take a 3phase supply to each flat! I know this is all against the norm, but this is an experimental "flagship" affair.
  • 0

    Simon Gallagher:

    I just had a quick look at SPENs earthing policy, and like most of the other DNOs they don’t seem to allow multiple services into ‘multiple occupied buildings’. . . 




    We would, providing the Ryefields were all next to each other. 


    Regards,


    Alan. 

  • 0

    To add a twist, they are all being fitted with 24kW 3-phase electric water heaters




    Presumably this is the equivalent of an electric combi-boiler, and instant hot water, no storage needed ? Such things are seen on the continent,  I have looked at a few installations like that in Berlin in the early 2000s.


    If  it is not also being used for radiators then the BS7671 style diversity assumptions will tend to oversize the combined supplies, as in reality not all flats will run a bath at once (though if it

    was supplying radiators you find that will all experience winter at the same time of year. ?)

    Equally how many KW of heating are there ?


    Still at rather more than 32A per phase just for water, you now need to give each flat at least a 45A 3 phase feed,  maybe 60, which is indeed going to eat up the ways in the Ryfield, but in reality not load them to anything like capacity for much of the time. I think you are going to have to try to get SPEN on-side if you can, as this is clearly going to look a bit odd.


    It may be worth thinking about  taking  3 phases to the cooker point (I assume no gas ?)  as  per continental practice,  or you will probably need 100 A fuses per flat, most modern  hobs and so forth have options for splitting the load over more than 1 phase, but I can imagine the fitters from Currys looking a bit non-plussed, given how hard they make it to reconnect just 3 wires.

     


  • 0
    Regarding the 24Kw water heaters. Ones that I have seen contain three elements, each of 8Kw, one element on each phase. Controlled individually by contactors or by solid state relays so as to give three different loadings according to water demand.


    If this is the case, then I strongly advise "rotating" the phases to either each flat or to each water heater. If this is not done, then I perceive some risk of overloading whichever phase supplies "one third heat"


    Rotating the phases between flats is probably the best option as it will better balance large single phase loads.

  • 0

    Alan Capon:




    Simon Gallagher:

    I just had a quick look at SPENs earthing policy, and like most of the other DNOs they don’t seem to allow multiple services into ‘multiple occupied buildings’. . . 




    We would, providing the Ryefields were all next to each other. 


    Regards,


    Alan. 


     




    Makes sense.


    Simon

  • 0

     



    Presumably this is the equivalent of an electric combi-boiler, and instant hot water, no storage needed ? 

     



    Correct. They are instantaneous water heaters serving domestic hot water only. The manufacturer has recommended a diversity of 15% based on their previous projects.


    I would have to find out what is being specified for the hobs. Being able to take 3-phase to the hobs would be good. I'll have to put it to the client and kitchen designer. But I think I'll end up with 100A fuses just to get the discrimination/selectivity.
  • Former Community Member
    0 Former Community Member
    Edited to say just noticed the 3 phase bit. Ryefield do make 3 phase versions, but obviously size is a very limiting factor.  35 flats x 3 phases = A HUGE AMOUNT OF FUSES


    Could you have 1 Ryefield per floor, or per 2 floors to keep the distances and number of ways down.


    Have you spoken to Ryefield? Most of these are pretty much made to order anyway, they might have a solution.
  • Former Community Member
    0 Former Community Member
    Thinking aloud but not the norm.........could you use a huge panel board with MCCB's??? Would need negotiation with the DNO and metering people for sure.


    Schneider have a projects team that could probably make a more secure version
  • 0
    Hi PeteTLM


    I'll get in touch with Ryefield and see if they have any solutions. In terms of using a panel board, I think we can only go down that route if we change the metering strategy, i.e. if the landlord has one in coming bulk supply they charges residents for electric via an MID meter.
  • 0
    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. 

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