A.Master electrician Rex Cauldwell responds: Yes, you can. Since you have installed 12-gauge wire, and since the breakers are there to protect the wiring, there is no reason you can’t install 20-amp breakers — as long as you don’t put more than three conductors in the conduit. If you install more than three conductors in the conduit, you would have to start to derate the conductors.

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