Specifications
FS-250 Installation and Operation Manual 
45 
Total System Currents 
    STANDBY (A)  ALARM (A) 
Total Panel and Modules current       
Total Auxiliary current    +  + 
Total Device current   +  + 
TOTAL PANEL+ Modules + DEVICES     
Use the Total Panel+ Modules + Devices for the Battery Size Calculations 
Battery Size 
Total Standby Current 
(from above) 
Hours of Standby Required per 
NFPA 72 Standard (4, 24 or 60) 
AH for Standby 
 A.  x ____ Hours  = 
Total Alarm Current 
(from above) 
5 Minutes of Alarm Operation 
per NFPA 72 Standard* 
AH for Alarm 
A. x 0.33 Hours  = 
A.H. for 
Standby 
A.H. for 
Alarm 
Calculated 
A.H. 
De-rating 
Factor 
A.H. Required 
Battery Capacity 
  + = X 1.25 = 
Notes: 
1.  An additional multiplier is included to compensate for the higher discharge rate in alarm. Battery capacity 
decreases with age. 
2.  The Standby current + Alarm current must never exceed 3.0 Amps when using one Transformer, and 
6.0amps when using the FS-NPE optional transformer assembly. 
3.  The following states the maximum standby current allowed for a FS-250 panel using a 38.5 AH battery 
set: 
60 hours of standby time is 0.457 Amps 
24 hours of standby time is 1.144 Amps 
4.  Does not include lamp or LED current, add separately. Refer to FS-SAU2 Installation Instructions for 
maximum activated current rating of individual drive circuits. 
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