What is the minimum trade size EMT required for a 45' long run containing various THHN/THWN conductors?

To determine the minimum trade size of EMT (Electrical Metallic Tubing) required for a 45-foot long run containing various THHN/THWN conductors, it's essential to consider the conduit fill, which is governed by Article conduit fill tables in the National Electrical Code (NEC).

For THHN/THWN conductors, you must account for their diameters and the number of conductors being installed. The NEC provides specific fill calculations to ensure that there is enough space for heat dissipation and to facilitate the installation of wires without excessive force.

Generally, for conductors such as THHN/THWN:

• One 1-inch EMT conduit can typically hold a certain number of THHN wires without exceeding 40% of the conduit’s internal area, which is the standard limit.

When calculating the fill for a run containing various sizes and quantities of THHN/THWN conductors, 1 inch is often sufficient for smaller installations and commonly used quantities. This size allows enough room to install a reasonable number of conductors while complying with NEC standards regarding fill capacity.

Oversizing the conduit (as with larger sizes) is often more expensive and unnecessary unless specifically needed for maintenance, pulling wires, or accommodating larger conductors. Therefore, in