Derated ampacity of 600 V conductors in conduit — NEC 2023 Table 310.16 with 310.15(B) and (C) correction and adjustment, plus Chapter 9 conduit fill
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Project Info
Circuits in This Project
Each circuit is one feeder or branch circuit and its raceway(s) — pick one to edit it. Changes autosave into the open project.
Circuit
Conductors
Raceway
Conditions, Load & Breaker
Results
Derated Ampacity
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Current-Carrying / Factor
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Overcurrent Device
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Raceway Fill
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Raceway Cross Section
Calculation
Conduit Fill (Chapter 9)
Project Summary
Method. NEC 2023, 2000 V and below. Allowable ampacity from Table 310.16 at the insulation's own temperature rating (Table 310.4(1), dry / damp or wet location), corrected for ambient per Table 310.15(B)(1)(1) and the 310.15(B)(2) rooftop adder (not for XHHW-2), and adjusted per Table 310.15(C)(1) for the current-carrying conductors in the raceway: neutrals counted per 310.15(E), grounding conductors not counted (310.15(F)), no adjustment in a nipple 24 in or shorter (310.15(C)(1)(b)). The displayed derated ampacity uses the insulation rating. Breaker selection assumes 75 °C terminations (110.14(C)): it uses the lower of the derated ampacity and the unadjusted Table 310.16 75 °C ampacity for all parallel sets. Equipment requiring 60 °C terminations needs a separate check. The breaker is checked against this limited ampacity per 240.4(B), (C) and (D), and the equipment grounding conductor is sized from the breaker per Table 250.122 (upsize only). Conduit fill per Chapter 9 Tables 1, 4, 5 and 8 (RHW-2 / USE-2 from a manufacturer's data sheet). Sizes through 750 kcmil. Verify against the adopted code edition before relying on the result.