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Use this handy tool to calculate the DC or AC voltage drop for a length of cable.
How to use this tool:
- Enter the initial voltage. Choose if your system operates on 12V or 24V.
- Select AC or DC. Choose which voltage type your system operates. Typically the selection will be 12V DC and 24V AC.
- Enter the current of your camera in amps. Note: 1 amp = 1000mA. Thus, if your camera draws 300mA, enter 0.3 into this field.
- Enter the distance of your cable in feet.
- Enter the size of your cable. CCTV standard is 18 awg.
- Click 'Calculate.' Click 'Cancel' to clear the results and start again.
Example 1
At 12V DC, a 300 mA camera at 100 feet on standard 18 awg will have a voltage drop of 0.38 volts. Industry standard is +/- 10% which is 1.2 volts. In this example, you are within limits.
Example 2
12V DC, 0.8 amps or 800ma (not unreasonable for an IR camera) at a distance of 150 feet on 18 awg would give you a drop of 1.54 volts, which is greater than acceptable limits.
The way to get around this is to have a shorter cable run, or increase the size of your power wire. In this example, increasing the power wire to 16 awg would decrease the voltage drop to 0.96 volts, which is within limits.
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