Honeywell MS-2 User Manual download pdf (Page 44)

Power Supply Calculations Overview

44 MS-2/MS-4 PN 51512:E 01/18/05

SECTION 5 Power Supply Calculations

5.1 Overview

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

5.2 Calculating 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 contin-

uously, 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 mm

) wire with 600 volt

insulation for this branch circuit.

Use Table 5-1 , to determine the total amount of current, in AC amperes (A), that must

be supplied to the system.

TABLE 5-1:120 VAC Branch Circuit Requirements

Device Type

Number of

Devices

Current Draw

(AC amps)

Total Current

per Device

MS-2/MS-4

MS-2E/MS-4E

2.3

1.15

[ ] X =

[ ] X [ ] =

Sum Column for AC Branch Current Required =

1 2 ... 39 40 41 42 43 44 45 46 47 48 49 ... 55 56

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Honeywell MS-2 User Manual Page 44