Can I mix 16 and 14 gauge wire?

Mixing 16 and 14 gauge is fine where both sizes are legal for the job: speaker runs, 12V accessory wiring, and cords. Current capacity follows the thinnest segment, so the 16 sets the limit.

On 120V branch circuits the answer flips. Building circuits start at 14 AWG on a 15 amp breaker, and a 16 gauge splice anywhere in that circuit is undersized and non-compliant.

In speaker wiring, a short 16 gauge tail on a 14 gauge run costs nothing audible.

For 12V work, remember drop stacks with every thin section; a mixed run is only as good as its skinniest stretch, so calculate on the 16.

The multiple wire gauge calculator handles mixed-size runs and shows the true combined limit.