Learn how to replace a single-pole light switch and a standard duplex outlet the safe, code-aware way. We start with planning and de-energizing at the breaker, then verify zero volts with a non-contact tester and multimeter. You’ll map conductors, label wires, and check box-fill before touching a screw. In the install phase, you’ll land hot, neutral, and ground on the right terminals, use pigtails for pass-throughs, and set device depth flush for a clean finish. Then we power up, test with a meter, and run quick heat and function checks. We close with common troubleshooting patterns—reverse polarity, open ground, loose back-stabs, half-switched confusion—and clear signs to call a licensed electrician. This is a calm, step-locked field guide you can follow in real time for safer results.