Protection
Conductor & OCPD Sizing
PV source circuits get 125 percent of short-circuit current, then 125 percent again for continuous duty. Rooftop conduit in the sun runs far above shade air temperature, and that correction factor throws away conductor ampacity. This calculator applies both.
What it asks for
- Circuit type
- Isc or continuous current (A) — PV: module Isc. Battery/AC: max continuous current.
- Parallel strings / units — Set to 1 for a single string or a single battery circuit.
- Ambient temp at conductor (°C) — Rooftop conduit in the sun runs well above shade air temp.
- Conductor
Simplified. Conduit fill adjustment (310.15(C)(1)) and rooftop conditions are not applied. Always verify against the current NEC adopted by your AHJ.