Section 6: Power Supply Calculations; Overview; Calculating The Ac Branch Circuit; Calculating The System Current Draw - Honeywell ECC-50/100 Instruction Manual

Section 6: Power Supply Calculations

6.1 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

6.2 Calculating the AC Branch Circuit

The audio distribution 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 transponder. Over-current 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.
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The ECC-50/100 requires 3.5 amps from the AC branch circuit. The ECC-50/100E requires 2.0
amps from the AC branch circuit.

6.3 Calculating the System Current Draw

6.3.1 Overview
The secondary power source (batteries) must be able to power the system during a primary power
loss. To calculate the non-fire alarm load on the secondary power source, use Calculation Column 1
in Table 6.3. The ECC-50/100 must support a larger load current during a fire alarm condition and
primary power loss. To calculate the fire alarm load on the secondary power source, use Calcula-
tion Column 2 in Table 6.3.
When calculating current draw and the battery size, note the following:
• 'Primary' indicates that the audio panel is being powered by AC
• 'Secondary' indicates that the audio panel is being powered by battery backup during AC
failure
• All currents are given in amperes (A) and refer to the DC current being supplied by the panel.
Table 6.1 shows how to convert milliamperes and microamperes to full amperes
96
To convert....
Milliamperes (mA) to
amperes (A)
Microamperes (µA) to µA x 0.000001
amperes (A)
Table 6.1 Converting to Full Amperes
Emergency Command Center Manual — P/N LS10001-000FL-E:G 5/3/2016
Multiply
mA x 0.001 3 mA x 0.001 = 0.003 A
300 µA x 0.000001 = 0.0003 A
Example