An 8 in by 8 in by 5 ft gutter will hold up to a maximum number of 4/0 THWN/THHN conductors. How many can be installed?

An 8 in by 8 in by 5 ft gutter will hold up to a maximum number of 4/0 THWN/THHN conductors. How many can be installed?

• A. 4
• B. 25
• C. 30
• D. 39

Answer: (D)

Conductor fill in a gutter is about fitting wires inside a raceway without exceeding the allowed cross‑sectional space. The NEC uses a fill limit (a percentage of the gutter’s interior cross‑section) and translates conductor size into an equivalent cross‑sectional area using circular mils. For gutters, there are tables that tell you how many conductors of a given size can be placed in a gutter of a given size and length. In this case, for 4/0 THWN/THHN conductors in an 8 by 8 inch gutter, the standard gutter-fill tables show that you can install up to 39 conductors. The length (5 ft) doesn’t change that count—the fill is determined by cross‑sectional space, not length. So 39 is the number that fits without exceeding the allowed fill.

Conductor fill in a gutter is about fitting wires inside a raceway without exceeding the allowed cross‑sectional space. The NEC uses a fill limit (a percentage of the gutter’s interior cross‑section) and translates conductor size into an equivalent cross‑sectional area using circular mils. For gutters, there are tables that tell you how many conductors of a given size can be placed in a gutter of a given size and length.

In this case, for 4/0 THWN/THHN conductors in an 8 by 8 inch gutter, the standard gutter-fill tables show that you can install up to 39 conductors. The length (5 ft) doesn’t change that count—the fill is determined by cross‑sectional space, not length. So 39 is the number that fits without exceeding the allowed fill.