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Life safety supplies

Frankie 223
Hello,


I m trying to understand the requirements of BS 9999 & BS 8519 regarding the generator sizing.


The standards require dual fire rated supplies to the sprinkler pumps and the generator should be able to support the LRC of the duty pump and the starting current of the secondary pump. This usually ends up in a generator size that appears to be oversized. 


If I provide one electric pump as duty and a diesel sprinkler pump as standby do I still need to provide an ats and secondary supply from the generator for the duty pump or I can just supply the duty pump from mains and size the generator for the rest of the life safety services (ff lifts, smoke extract fans, ff lobby lighting etc..) ?




Also, does anyone knows if this is a cost effective solution or is it better to provide two electric pumps and size the generator accordingly?
  • 0
    Chris


    You should have watched the webinar of Safety Services. https://electrical.theiet.org/courses-resources-career/technical-webinars/


    What does the fire strategy for the building say? The electrical design flows from that. It could be the electrical pump would need a secondary supply or the diesel sprinkler pump is the acceptable secondary source as an alternative to the electric pump. I have not seen it done that way, which does not it is never done.
  • 0
    Frankie,

    If you use the electric pump as the primary and a diesel sprinkler pump as secondary, then you only need to size the generator for the other life safety systems. 

    Just remember though, the sprinkler primary supply is still a Life Safety System and as such the requirements for fire rating of the cable, the routing of it and protection by fuses not MCBs, still apply.

    It will reduce the size of generator required considerably and is regularly (but not exclusively) used as the most cost effective solution. I would cost both options and check the space requirements of both too. Space often overrules cost in high rise buildings.


    regards,

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