Supply for 50 flats in 5 storey block of flats

[nicr4m]

Hi all,

I hope you could share your experience and advice regarding supply 50 flats in 5 storey block of flats. We get 3 x 430A supply.
What would be the best option for distribution power to each flat? I was thinking of 3 ryefield boards on 4th, 2nd and ground floor, however it will require 5x185mm SWA to run to each ryefield, optionally 3x185mm SWA and supply each ryefield as single phase (?).

It might be silly question but until now we did only max 2 storey buildings and all flats were supply from 1 location and max supply was 3 x 200A, here is my next question comes. Until now we only connect ryfield board, which maximum CSA cable for termination was 120mm, how to terminate 185mm cable then ?

Many thanks for help.

 

[Rockingit]

You can get clamp adaptors up to 240mm (I think). But have you considered doing parallel runs of smaller csa instead of having to wrestle with 185mm?

 

[davesparks]

Are you sure on your cable sizing? 185mm seems a little oversized at first glance, especially for the lower floors.

To keep things logical you could install 1 ryefield board per floor. This would reduce the size of cable required to a more manageable level and reduce the impact of any fault which may occur on one of those submains.

 

[Rockingit]

Are you sure on your cable sizing? 185mm seems a little oversized at first glance, especially for the lower floors.

To keep things logical you could install 1 ryefield board per floor. This would reduce the size of cable required to a more manageable level and reduce the impact of any fault which may occur on one of those submains.

I'd not really looked at that - my guess would be 10 flats per floor on 60A each, so you've basically got a theoretical max of 200A /ph on each sub main - ergo you'd have a stream of 430 DNO > 400A BNO > 5no ( 200 > 60 ) in which case 185mm does seem a bit keen unless there's issues of distance and vd?

 

[Rockingit]

Just something else - Ryefield boards have a PEN connector/enabler so you might also consider whether you need to run 5c or 4c (making an assumption that this installation is an official BNO setup).