FIG. 00 — IN PROGRESS
TRANSFORMER FEEDER CALCULATOR
Size transformer primary and secondary feeders and overcurrent protection. Calculates primary FLA from KVA and voltage, applies NEC 450.3 protection rules, sizes both primary and secondary conductors.
⚠ STATUS · TOOL UNDER FINAL VALIDATION
We're finalizing this calculator's NEC validation. In the meantime, use the conduit fill calculator and the wire fill chart on the homepage.
FIG. 01
WHAT THIS TOOL WILL CALCULATE
- 01Input: transformer KVA, primary voltage, secondary voltage, phase (1Φ / 3Φ)
- 02Output: primary full-load amps, primary OCPD size per NEC 450.3, secondary FLA, secondary OCPD
- 03Applies the 125% / 250% rules per NEC 450.3(B) Table 1
- 04Sizes both primary and secondary conductors with appropriate ampacity headroom