UPS back up time

[Grouch1980]

I have a space that falls under a group A occupancy group… assembly space, and it has a stage so it needs a fire alarm system with a pre-signal panel in the auditorium.

Per this section in the nyc building code, I have to back up the fire alarm system with an emergency system. I’m looking at chapter 27, section 2702.2.1.1. If I use a UPS, how long do the batteries have to last / what’s the back up time required?



Thanks!

 

[ron]

Most UPSs are not considered Emergency power per their listing and backup time. To be a UPS per Article 700 requires a lot of battery

The fire alarm generally has battery backup for 24 hours+ (depending on the application) integrated in with power supplies that would be the Emergency Power.

 

[Grouch1980]

Most UPSs are not considered Emergency power per their listing and backup time. To be a UPS per Article 700 requires a lot of battery

The fire alarm generally has battery backup for 24 hours+ (depending on the application) integrated in with power supplies that would be the Emergency Power.

So I don’t need a separate UPS? I know the fire alarm panel has integral batteries, but I don’t know if those batteries count as the “UPS” that this section mentions.

It’s a small building I’m working on. I don’t need an emergency or standby generator.

This fire alarm system with pre signal is the only thing pushing me into this code section.

 

[PaulMmn]

The 'large shoe box' size UPSs intended for home/business computers only have about a 20 minute run time-- intended to give your computers time to shut down gracefully in the event of a power failure.
A UPS with longer run time usually means more batteries-- at my office we have a UPS (pretty sure it's an 'always on' model) that takes a good 2' x 8' (and maybe 7' tall). It's only rated 20-30 minutes, and keeps the computers (a computer room with multiple servers, storage, tape library, etc), phone system, and some emergency lights on. Enough time for the generator to kick in.
If you're using a UPS to run the fire alarm system, you'll need a lot of battery-- how much do the alarms/lights take? Does the fire alarm system and its power source need to be in a 'fire-proof' room?

 

[gadfly56]

The 'large shoe box' size UPSs intended for home/business computers only have about a 20 minute run time-- intended to give your computers time to shut down gracefully in the event of a power failure.
A UPS with longer run time usually means more batteries-- at my office we have a UPS (pretty sure it's an 'always on' model) that takes a good 2' x 8' (and maybe 7' tall). It's only rated 20-30 minutes, and keeps the computers (a computer room with multiple servers, storage, tape library, etc), phone system, and some emergency lights on. Enough time for the generator to kick in.
If you're using a UPS to run the fire alarm system, you'll need a lot of battery-- how much do the alarms/lights take? Does the fire alarm system and its power source need to be in a 'fire-proof' room?

You won't really need "a lot of battery" IFF the load is the fire alarm system only, and it really depends on how long you want the UPS to carry that load, remembering that the panel has to be designed to be 24 hours in standby with internal batteries, and since it's a voice system, 15 minutes of alarm operation. That can be accomplished with a couple of 12 volt 35 Ahr batteries, or even 12 volt 7 Ahr for non-voice systems. It's pretty amazing how long fire alarm control units operate on relatively small batteries.

 

[Grouch1980]

You won't really need "a lot of battery" IFF the load is the fire alarm system only, and it really depends on how long you want the UPS to carry that load, remembering that the panel has to be designed to be 24 hours in standby with internal batteries, and since it's a voice system, 15 minutes of alarm operation. That can be accomplished with a couple of 12 volt 35 Ahr batteries, or even 12 volt 7 Ahr for non-voice systems. It's pretty amazing how long fire alarm control units operate on relatively small batteries.

How long is it needed to carry the fire alarm load?

 

[gadfly56]

How long is it needed to carry the fire alarm load?

Maybe 48 hours? If you had an on-site generator, usually you can't store more than 48 hours worth of fuel, and natural gas generators aren't usually approved because you don't have on-site fuel storage.

 

[Grouch1980]

Maybe 48 hours? If you had an on-site generator, usually you can't store more than 48 hours worth of fuel, and natural gas generators aren't usually approved because you don't have on-site fuel storage.

or maybe it's only 6 hours. Because an emergency generator only needs fuel for 6 hours of back-up time.

I wish these code sections were clearer.

 

[ron]

So I don’t need a separate UPS? I know the fire alarm panel has integral batteries, but I don’t know if those batteries count as the “UPS” that this section mentions.

It’s a small building I’m working on. I don’t need an emergency or standby generator.

This fire alarm system with pre signal is the only thing pushing me into this code section.

In the same way 700.12(C)(4) Storage Batteries and UPS. relies on the batteries in battery-equipped emergency luminaires to accomplish the Emergency Power, I have used the batteries in the FACP secondary power source (per NFPA 72) as the Emergency Power Required by the Building Code.

 

[Grouch1980]

In the same way 700.12(C)(4) Storage Batteries and UPS. relies on the batteries in battery-equipped emergency luminaires to accomplish the Emergency Power, I have used the batteries in the FACP secondary power source (per NFPA 72) as the Emergency Power Required by the Building Code.

did you mean 700.12(C)? there is no 700.12(C)(4).

 

[topgone]

or maybe it's only 6 hours. Because an emergency generator only needs fuel for 6 hours of back-up time.

I wish these code sections were clearer.

For calculation's sake, say you have a 200 AH battery and you wanted to have a backup time of 6 hours. Keep in mind that you are only allowed to discharge 50% of 200AH and that due to the efficiency of your inverter (say 90% efficient), you only get to load your battery with a load of (200AH X0.9 X 0,5)/6 hours = 15 amps, not the full 20A (10-hour rate).
The best example of this is my buying a 600W UPS with a internal battery of 12V, 9AH (APC). The available backup time was only 8 minutes when loaded with 600W of load, as claimed by APC.
Basically, your backup time depends on the AH of the battery and the battery load (backup time = (Battery AH x eff X DoD)/load amps.