Battery back-up

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Grouch1980

Grouch1980

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New York, NY
Hi all,
I'm looking at NYC Electrical Code section 760.41(C)(1), which discusses the battery back-up time for fire alarm systems. This is the NYC code, but I believe other jurisdictions have similar language:

With Voice Communications Capability. Supervisory operation for 24 hours followed by full load operation for 6 hours for systems with voice communications capability.

FPN: A 45 minute period of voice and alarm operation at the maximum connected load shall be considered equivalent to 6 hours of total system operation.

I do not understand the language.
1. What exactly is 'supervisory operation'?
2. In the event of emergency back-up, why does full load operation 'follow' supervisory operation? Wouldn't you want full load operation from the start? I know I'm wrong, I just don't understand the language.
3. Is the FPN saying I only need 45 minutes of back up, rather than 6 hours?

Thanks!
 
1. Supervisory operation is when the FACPs are idle (not in alarm, but monitoring for initiating devices)
2. This is 24 hours of supervisory and then 6 hours of "normal" notification device actuation. For a high rise building, it is selective evacuation, so notification devices will only be on for 2 or 3 floors at a time.
3. This says that if you run all notification devices at the same time (not typical when voice alarms are used), you can do that for 45 minutes, rather than the 6 hours of "normal" notification operation in a selective evacuation mode.
 
ok... I got #1 and #3... thanks!

But for #2, why does it say 'followed by'? Is it saying that we need 24 hours of supervisory operation of the initiating devices, and if an alarm condition happens at any time within this 24 hour window, then we need a max of 6 hours to back up the notification appliances?
 
and... I'm assuming once those 24 hours have passed, and there was no alarm, even though there's 6 hours of full load operation left, those notification devices will never go off since the intitiating devices are disengaged... is this correct?
 
Grouch1980 said:
ok... I got #1 and #3... thanks!

But for #2, why does it say 'followed by'? Is it saying that we need 24 hours of supervisory operation of the initiating devices, and if an alarm condition happens at any time within this 24 hour window, then we need a max of 6 hours to back up the notification appliances?
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I have interpreted it as 23 hours and 59 minutes have passed, then the panel needs to run in supervisory mode and run evacuation for 6 additional hours.
 
ron said:
I have interpreted it as 23 hours and 59 minutes have passed, then the panel needs to run in supervisory mode and run evacuation for 6 additional hours.
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Agreed. It should be noted, although you did mention it, that this is not every notification appliance in the entire space rolling. Voice systems are usually partial evacuation, so only the affected areas need to be notified.
 
ron said:
I have interpreted it as 23 hours and 59 minutes have passed, then the panel needs to run in supervisory mode and run evacuation for 6 additional hours.
Click to expand...
I still don't get it. What if there's an alarm condition within those 23 hours and 59 minutes? Does the system then run in evacuation mode for 6 hours?
 
Grouch1980 said:
Thanks Ron.

So if I was to specify a UPS such as this, is this acceptable?
https://www.onlinepower.com/pdf/fab_DS.pdf

By looking at the cutsheet, what do you select for 24 hours of standby? I'm assuming this is something to be selected by the fire alarm vendor, since they would know how much power is needed for their devices while on standby?
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Why are you worrying about this? You should not be specifying anything separate related to battery backup for the fire alarm outside of whatever is in the standard fire alarm spec. The fire alarm vendor will do battery calculations based on the panel configuration and will choose the battery size he needs and put them in the bottom of the panel or in a separate battery box. Part of his submittal package should be a copy of the battery calculations which you can double check if you wish. Other than that, I wouldn't concern yourself.
 
Grouch1980 said:
Thanks Ron.

So if I was to specify a UPS such as this, is this acceptable?
https://www.onlinepower.com/pdf/fab_DS.pdf

By looking at the cutsheet, what do you select for 24 hours of standby? I'm assuming this is something to be selected by the fire alarm vendor, since they would know how much power is needed for their devices while on standby?
Click to expand...
You cannot use an outside UPS to do this function. The fire alarm vendor will size battery boxes (with batteries) and the needed battery chargers / power supplies to support the calculated load. It needs to be listed for fire alarm.
 
ron said:
You cannot use an outside UPS to do this function. The fire alarm vendor will size battery boxes (with batteries) and the needed battery chargers / power supplies to support the calculated load. It needs to be listed for fire alarm.
Click to expand...
Well, I got hit with an objection from the FDNY on my fire alarm drawings. He pointed out this section from the NYC Building Code (my project is a group A occupancy):

2702.2 Where required.
Emergency and standby power systems shall be provided where required by this section.
2702.2.1 Group A occupancies. Emergency power shall be provided for voice/alarm communication systems in Group A occupancies in accordance with Section 907.5.2.2.5.
2702.2.1.1 Prior code buildings. In prior code buildings, where a stationary generator is not otherwise required, the power source for emergency power to the voice/alarm communication system may be served by a gas generator or an uninterruptable power source (UPS) in accordance with the New York City Electrical Code.

It's in an old low-rise building. There is no generator. Nor do we want to add one. I spoke to the expeditor, and he says we fall under 2702.2.1.1 (the last paragraph above)... it mentions the use of a gas generator or a UPS. So this is not describing a stand-alone UPS, outside of the fire alarm system? Ron, you're saying the integral batteries in the main fire alarm panel makes me comply with the last paragaph above?
 
The uninterruptable power source is differentiated from storage batteries in NYC Electrical Code 700.12(A) and (C). I'm not sure what the 24 hour battery associated with the FACP would be. Sorry.
 
Grouch1980 said:
Well, I got hit with an objection from the FDNY on my fire alarm drawings. He pointed out this section from the NYC Building Code (my project is a group A occupancy):

2702.2 Where required.
Emergency and standby power systems shall be provided where required by this section.
2702.2.1 Group A occupancies. Emergency power shall be provided for voice/alarm communication systems in Group A occupancies in accordance with Section 907.5.2.2.5.
2702.2.1.1 Prior code buildings. In prior code buildings, where a stationary generator is not otherwise required, the power source for emergency power to the voice/alarm communication system may be served by a gas generator or an uninterruptable power source (UPS) in accordance with the New York City Electrical Code.

It's in an old low-rise building. There is no generator. Nor do we want to add one. I spoke to the expeditor, and he says we fall under 2702.2.1.1 (the last paragraph above)... it mentions the use of a gas generator or a UPS. So this is not describing a stand-alone UPS, outside of the fire alarm system? Ron, you're saying the integral batteries in the main fire alarm panel makes me comply with the last paragaph above?
Click to expand...
If you go to the NYC electrical code, it doesn't seem to require the secondary power source. It only describes what to do IF it is present. I think the FDNY examiner isn't reading the NYC electrical code.
 
gadfly56 said:
If you go to the NYC electrical code, it doesn't seem to require the secondary power source. It only describes what to do IF it is present. I think the FDNY examiner isn't reading the NYC electrical code.
Click to expand...
Apologies for my late response. Would you know exactly which code section in the NYC electrical code you're referring to?
 
Regarding #2:
If there is no alarm initiation during the 24 hour period, there will, as a practical matter, be remaining battery capacity to continue running in supervisory mode for some additional time, with less than 6 hours of full load (alarm condition) operation if the alarm is finally triggered during that extra time. But the Code does not concern itself with the details of what happens during that time.
The assumption seems to be that by the end of the 24 hour period either power will be restored, additional backup power will be provided, or the building will be evacuated of placed under a fire watch.
 
GoldDigger said:
Regarding #2:
If there is no alarm initiation during the 24 hour period, there will, as a practical matter, be remaining battery capacity to continue running in supervisory mode for some additional time, with less than 6 hours of full load (alarm condition) operation if the alarm is finally triggered during that extra time.
Click to expand...
Ah, makes sense. Thanks!
 
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