Wire size is based primarily on:
- Maximum current
- Cable length
- System voltage
- Acceptable voltage drop
Higher current and longer cable runs generally require larger wire.
To size a cable:
- Determine the maximum current the circuit will carry.
- Measure the total circuit length.
- Determine the acceptable voltage drop.
- Select wire that can safely carry the required current while keeping voltage drop within the desired range.
Low-voltage systems, especially 12V systems, can be particularly sensitive to voltage drop.
Good terminations are just as important as the wire itself. Loose connections, poor crimps, and corrosion create resistance and heat even when the cable is correctly sized.
