FireWarden 100-2/E — P/N 52778:A 11/04/2005 159
Calculating the System Current Draw Power Supply Calculations
When calculating current draw and the battery size, note the following:
• ‘Primary’ refers to the main power source for the control panel
• ‘Secondary’ refers to the control panel’s backup batteries
• All currents are given in amperes (A). Table 7.2 shows how to convert milliamperes and
microamperes to full amperes.
7.3.2 How to Use Table 7.3 on page 160 to Calculate System
Current Draw
Use Table 7.3 on page 160 to calculate current draws as follows:
1. Enter the quantity of devices in all three columns
2. Enter the current draw where required. Refer to the Device Compatibility Document for
compatible devices and their current draw
3. Calculate the current draws for each in all columns
4. Sum the total current for each column
5. Copy the totals from Column 2 and Column 3 to Table 7.4 on page 161
Following are the types of current that can be entered into Table 7.3 on page 160:
• Calculation Column 1 - The primary supply current load that the control panel must
support during a non-fire alarm condition, with AC power applied.
• Calculation Column 2 - The primary supply current load that the control panel must
support during a fire alarm condition, with AC power applied.
• Calculation Column 3 - The standby current drawn from the batteries in a non-fire alarm
condition during a loss of AC power.
Table 7.2 Converting to Full Amperes
To convert... Multiply Example
Milliamperes (mA) to
amperes (A)
mA x 0.001 3 mA x 0.001 = 0.003A
Microamperes (
µA) to
amperes (A)
µA x 0.000001 300 µA x 0.000001 = 0.0003 A
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