Calculating The Battery Size; 1: Nfpa Battery Requirements; 2: Selecting And Locating Batteries - Fire-Lite MS-2E' MS-4E User Manual

Calculating the Battery Size

TABLE 5-4:Total Secondary Power Requirements at 24 VDC
Secondary Standby Load
(total from Table 5-3 Calculation
Column 3)
[ ]
Primary Alarm Load
(total from Table 5-3 Calculation
Column 2)
[ ]
Sum of Standby and Alarm Ampere Hours
Multiply by the Derating Factor
Battery Size, Total Ampere Hours Required
MS-2/MS-4 PN 51512:D 10/18/04
5.4 Calculating the Battery Size
Use Table 5-4 to calculate the total Standby and Alarm load in ampere hours (AH).
This total load determines the battery size (in AH), required to support the control panel
under the loss of AC power. Complete Table 5-4 as follows:
1. Enter the totals from Table 5-3 on page 46, Calculation Columns 2 and 3 where
shown
2. Enter the NFPA Standby and Alarm times (refer to 'NFPA Requirements'
below)
3. Calculate the ampere hours for Standby and Alarm, then sum the Standby and
Alarm ampere hours
4. Multiply the sum by the derating factor of 1.2 to calculate the proper battery size
(in AH)
5. Write the ampere hour requirements on the Protected Premises label located
inside the cabinet door
Required Standby Time
(24 or 60 hours)
X[ ]
Required Alarm Time
(for 5 min., enter 0.084,
for 10 min., enter 0.168)
X[ ]
5.4.1 NFPA Battery Requirements
• NFPA 72 Local, Central and Proprietary Fire Alarm Systems require 24 hours of
standby power followed by 5 minutes in alarm
• NFPA 72 Auxiliary and Remote Station require 60 hours of standby followed by
5 minutes in alarm. Batteries installed in a system powered by a generator need
to provide at least 4 hours of standby power
5.4.2 Selecting and Locating Batteries
Select batteries that meet or exceed the total ampere hours calculated in Table 5-4 . The
control panel can charge batteries in the 7 AH to 18 AH range. The control panel cabi-
net is capable of housing batteries up to 7 AH. Batteries larger than 7 AH require the
BB-17F or other UL listed external battery cabinet.
Power Supply Calculations
= AH
= AH
= AH
X 1.2
= AH
47