Conduit fill
Chapter 9, Table 1 sets the general fill limits: 53% for one conductor, 31% for two, and 40% for three or more. Tables 4 and 5 supply the raceway and insulated-conductor areas. Include neutrals and insulated equipment grounds in the physical fill.
For more than two conductors of the same size and insulation, Table 1 Note 7 permits a calculated capacity with a fractional part of at least 0.8 to round up. PassPull shows when it uses that allowance. It never applies it to mixed wire sizes.
Ampacity and conductor count
Table 310.16 provides base ampacities. Table 310.15(C)(1) provides adjustment factors when more than three current-carrying conductors share the raceway. For example, four through six use an 80% factor; seven through nine use 70%.
Sections 310.15(E) and (F) govern neutral and grounding-conductor treatment. Equipment grounds do not count for ampacity adjustment. Neutral treatment depends on the circuit, not the label on the wire.
Heat and equipment connections
Table 310.15(B)(1)(1) supplies ambient-temperature correction factors. This checker uses the 90°C column for dual-rated THHN/THWN-2 conductors, then checks the equipment termination ceiling under 110.14(C).
The insulation’s temperature rating does not establish the terminal rating. Check the lowest applicable rating at the connected equipment.
Loads, protection, and circuit grouping
Sections 210.19(A)(1) and 215.2(A)(1) address conductor sizing for loads, as applicable. PassPull’s continuous-load option uses a conservative 125% requirement. It is not a full branch-circuit or feeder design calculation.
Section 240.4(D) sets ordinary small-conductor overcurrent protection limits. A calculated 32 A ampacity for #10 copper does not approve a 35 A breaker. Section 300.3(B) matters when moving complete circuits to separate raceways.