Number of wires in conduit

[Teo2006]

Installing dishwasher. New install. Need to run electic-separate 15amp circuit. Would like to feed wires through nearby conduit run. How many conductors and neutrals can run in a 1/2 or 3/8 conduit ?

[Member, Takoma Park Volunteer]

The limit is on the total number of wires. The capacity of those wires may need to be derated if there are more than three current carrying conductors in the conduit. Conductors that are functioning as actual neutral conductors are not counted for that purpose but grounded current carrying conductors other than true neutrals are. To answer your question about the total number of wires permitted in the conduit I would need to know the actual type and nominal size of conduit or at least it's actual internal diameter. Conduits carrying three or more wires may only be filled to 40% of their cross sectional area.

[gfretwell]

Short answer 9 #12 THHN

[Calvin Henry-Cotnam]

I created a Conduit Calculator application that is available for free at

[Tazz]

I think its safe to say you can install (3) #12 thhn wires in a 1/2 conduit. 40% fill. Assuming your dishwasher is 120v ac