5 Steps to Test an Extension Cord With a Multimeter

Set your multimeter to continuity or low ohms (200 Ω range). Test each conductor end-to-end, from plug blade to corresponding slot in the female end.

Check for near-zero resistance on each conductor. High resistance above a few ohms means internal fray or corrosion.

Test each conductor to the ground pin. It should show open (infinite). Continuity means compromised insulation.

Look for visible damage first. Cuts, kinks, melted plastic, or a loose plug are obvious signs to replace the cord.

Replace the cord if any test fails or you are unsure. New cords are cheap; don’t risk a fire.