Fire Alarm Power Density

[cvirgil467]

When ball parking power requirements for fire alarms systems at the earlier stage of design, is there a power density (w/sq.ft) typically used, similar to lighting loads or general purpose loads?

Thanks.
C

 

[Sahib]

I think for fire detection, AC power requirement is negligible.
It is quite another matter for fire protection.

 

[mgookin]

It's going to vary considerably based on your floorplan because that's what's going to dictate how many stobes, horns, etc. you have. I say the answer is no.

 

[steve66]

I think for fire detection, AC power requirement is negligible.
It is quite another matter for fire protection.

Negligible from the building power side, but my guess is that he is trying to get a rough idea what size battery backup is necessary for the fire alarm panel.

The fire alarm code requires the system to be able to run for a certain length of time without building power.

 

[gadfly56]

Following the general advice to "write about what you know", the Siemens FireFinder XLS has a 12 amp power supply that pulls 3.5A at 120VAC. I can load four of them - which is the max you can put in a single enclosure - on a 15 amp circuit . The XLS is a high end panel and it's difficult to imagine anything out there that would need 48 amps of DC power, except maybe a very badly designed voice evac system. Really huge buildings will have transponder panels with the same limitations.

A ten-story building with 10,000 sqft per floor would be 14amps/100,000 sqft or 0.00014 amps/sqft. Do you really care?

The important thing to note is that the fire alarm system will require a dedicated circuit. So will each booter panel or transponder panel, if they are remote from the main panel.