What is the maximum number of 12 AWG THHN conductors allowed in a trade size 1 EMT?

The maximum number of 12 AWG THHN conductors allowed in a trade size 1 EMT (Electrical Metallic Tubing) is based on the calculations from the National Electrical Code (NEC), which includes factors such as the conductor's size, insulation type, and the trade size of the conduit.

For 12 AWG conductors, the NEC specifies an allowable fill for conduits. In a trade size 1 EMT, the total cross-sectional area of the conductors is considered to ensure that they fit without exceeding the conduit fill limits. The NEC allows a certain percentage of fill based on the conduit size and the number of conductors, which in this case results in a maximum of 26 conductors for 12 AWG THHN wire.

This number is derived from both the conduit fill tables within the NEC and the fact that THHN conductors have a smaller diameter compared to some other types of insulation. Thus, the calculated fill for the EMT, following the guidelines and rules in the NEC, confirms that 26 is the maximum permissible quantity for 12 AWG THHN conductors within that size of the EMT.