Overview

Power Supply Calculations

SECTION 7 7.1 Overview

Power Supply Calculations

This section contains instructions and tables for calculating power supply currents in alarm and standby conditions. This is a four-step process, consisting of the following:

1.Calculating the total amount of AC branch circuit current required to operate the system

2.Calculating the power supply load current for non-fire and fire alarm conditions and calculating the secondary (battery) load

3.Calculating the size of batteries required to support the system if an AC power loss occurs

4.Selecting the proper batteries for your system

7.2Calculating the AC Branch Circuit

The control panel requires connection to a separate, dedicated AC branch circuit, which must be labeled FIRE ALARM. This branch circuit must connect to the line side of the main power feed of the protected premises. No other non-fire alarm equipment may be powered from the fire alarm branch circuit. The branch circuit wire must run

continuously, without any disconnect devices, from the power source to the control panel. Overcurrent protection for this circuit must comply with Article 760 of the National Electrical Codes as well as local codes. Use 14 AWG (2.00 mm2) wire with 600 volt insulation for this branch circuit.

Use Table 7.1 , to determine the total amount of current, in AC amperes (A), that must be supplied to the system.

Table 7.1 AC Branch Circuit Requirements

Device Type

Number of

 

Current Draw

 

Total Current

Devices

 

(AC amps)

 

per Device

 

 

 

 

 

 

 

 

 

 

 

MS-9200UDLS

 

 

 

 

3.00

 

 

or

 

1

X

 

or

=

 

MS-9200UDLSE

 

 

 

 

1.50

 

 

 

 

 

 

 

 

 

 

CHG-75

[

]

X

 

2.05

=

 

 

 

 

 

 

 

 

 

CHG-120F

[

]

X

 

2.00

=

 

 

 

 

 

 

 

 

 

 

[

]

X

[

]

=

 

 

 

 

 

 

Sum Column for AC Branch Current Required

=

 

 

 

 

 

 

 

 

 

MS-9200UDLS PN 52750:A 11/04/05

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