BS9251 Power supplies to Sprinkler booster pump.

[kurnal]

A residential sprinkler system to BS9251 has been installed in a new small 3 storey care home for 5 adults with learning disabilities, 24 hr support.

The system is certified as a residential system and has a 38mm or thereabouts copper mains feed with an electric booster pump. Tested output on commissioning cert is 142 L/Min @ 2.8Bar - I would have expected 168L/min- though would only have required  1.5Bar as the minimum. I am not too worried as no room has more than two heads due to size and no relaxations have been made as a result of sprinkler installation- so its not likley that more than two heads would ever operate.

The bugbear is the power supply to the pump. The feed to the sprinklers and alarm are from dedicated mcbs on the main building distribution board ( a large domestic style consumer unit) on the non RCD protected side. I think a dedicated supply should have been taken from the meter independent  from the other circuits feeding the building, as one of the first actions of the fire service on entering the building will be to isolate the mains- which will disable the pump feeding the sprinklers.

Furthermore although the sprinkler panel to pump connection is in FR cable the feed from distribution board to panel is pvc twin and earth.

I am not happy with the electrical arrangements but the installer is a reputable company and fire officer does not see a problem. The installer say they always do it that way and I am talking out of my backside.

The BS appears to be open to interpretation. The commissioning certificate does not mention any variations except for there being no sprinklers in the roof space- but no justification is given. I have given instruction to the staff and left a briefing note for the fire service with photo of the dis board and instructions on how to shut down leaving sprinkler running.

I would be grateful to hear any other opinions.

[Goodsparks]

Its a bit like the old fire alarm switchfuse being installed upstream of the main switch. BS7671 (Reg. 357.1.6) requires a main linked switch or linked circuit breaker be provided as near as practicable to the origin of the installation as a means of switching the supply on load and as a means of isolation.

I would see an additional isolator or D/B as a deviation from BS7671 as there would be more than one means of isolation.

Depending on the location of the CCU / proximity to sprinkler panel, I too would expect to see it installed in FR cable (Reg. 560.8.1) assuming the panel does not contain a battery backup that would operate the pump in the event of mains failiure ?

Paul

[kurnal]

Depending on the location of the CCU / proximity to sprinkler panel, I too would expect to see it installed in FR cable (Reg. 560.8.1) assuming the panel does not contain a battery backup that would operate the pump in the event of mains failiure ?

Paul

Thanks Paul
If the panel does contain a battery to run the pump I would like to know the spec as the panel is about 1/5 the size of the 240v pump!

[wormhole]

you are correct, BS9251 requires use of fire rated cabling for the mains feed, it also states the supply should be derived before the DB however personally I think this will be a electrical hazard and I would always use a outgoing way of the first piece of switch gear, obiviously clearly marked in the same way as fire alarms.

normally the control panels are quite basic and can drive sounders (if no fire alarm installed) therefore only have batteries for the sounders and not for the pump - as 16A (SP) will require massive amounts of batteries for any prolonged use.

[kurnal]

Thanks wormhole.
It seems then that once again we have a little conflict between BS7671 and a fire safety standard- in this case BS9251, as well as BS5839 and  I believe there is a similar conflict with BS5266 part 1.

This conflict is a real problem as whilst the fire safety standards are specific in the responsibility of the system design and commissioning engineers time and time again ( and I am sure for very good reasons) the electrical engineer rules the day and installs to his interpretation of BS7671 - yet I never see variations declared on the commissioning certificates for fire alarms, emergency lighting or sprinkler systems.

I find this very surprising as many of the members of the BSI committees are both MIFireE and MIEE- you would have thought this could have been resolved before the publication of the standards.