12V Wire Voltage Drop Calculator
Estimate voltage drop on 12V DC runs by wire gauge, current, and cable length for gate openers and rural DC circuits.
Common questions
- What wire gauge do I need for a 12V solar panel run?
- For a 20W panel run under 25 ft, 14 AWG is fine. Beyond 40 ft, step up to 12 or 10 AWG to keep voltage drop under 3%.
- Why does voltage drop matter for a 12V system?
- A drop over 3% starves the charge controller — batteries never reach full charge and cycle life drops sharply.
- Can I use household extension cord for a 12V run?
- Short lengths in a dry indoor run only. For outdoor solar wiring, use direct-burial rated or UV-rated stranded wire in conduit.
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