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Feeder Tap Rule Calculator (NEC 240.21(B))

Checks a feeder tap conductor against the 10-ft, 25-ft, or outside unlimited-length tap rules of NEC 240.21(B) — the conditions that let a tap conductor be smaller than would otherwise be required for the feeder's overcurrent device.

AAJappsEngineering Calculation Report

Feeder Tap Rule Calculator (NEC 240.21(B))

NEC 240.21(B)(1) 10-ft tap, 240.21(B)(2) 25-ft tap, 240.21(B)(5) outside unlimited-length tap

Generated

For preliminary engineering use only — always verify results against project-specific standards and a qualified engineer's review before use in a real design.

Tap rule & feeder

A
A
ft
A

Installation conditions

Tap rule compliance

Tap length ≤ 10 ft8 ft
Tap ampacity ≥ 1/10 of feeder OCPD60A ≥ 40.0A required
Protected from physical damage (enclosed in raceway)Yes
Terminal OCPD rating ≤ tap ampacity60A ≤ 60A
COMPLIANT ✓