Should I use an extension cord with a dimmer switch?

No, you shouldn’t generally use an extension cord with a dimmer switch. It can cause flickering, poor dimming, or failure because the extra resistance messes with the dimmer’s load sensing. Many dimmers need a neutral wire, which most extension cords lack, creating voltage drop or short risks. If you must, use a short, heavy-duty 12 or 14 gauge cord and ensure the dimmer is rated for the total load, but it’s still a hack, not a permanent solution.