What are conduit fill and its purpose?

• A. The maximum allowed length of a conduit run.
• B. The number of conduits that can be installed in a raceway.
• C. The percentage of a conduit’s interior cross-section occupied by conductors and fittings; ensures space for heat and pulling conductors.
• D. The material type used for conduit.

Answer: (C)

Conduit fill is the percentage of a conduit’s interior cross-section that is occupied by conductors and fittings. This measurement ensures there’s enough space inside the raceway for heat to dissipate and for pulling wires through without crowding. Following proper fill prevents overheating and makes future pulling or adding conductors easier, keeping installation safe and compliant with NEC guidelines. The other ideas—length, number of conduits, or material—don’t describe how much of the conduit’s interior is taken up by conductors and fittings.