3 Ways to Test an Extension Cord for Internal Damage

Use a multimeter set to continuity or low resistance Plug nothing in. Test each conductor from one end to the other — live to live, neutral to neutral, ground to ground. Infinite resistance or no beep means the wire is broken inside. Any reading above a few ohms for a short cord indicates corrosion or a partial break, making the cord unsafe under load.

Try the old lamp trick as a quick check Plug in a small light and wiggle the cord along its length. If the light flickers, you have found a break. This method only reveals obvious breaks, not high resistance or partial damage.

Replace the cord if you lack a multimeter A new extension cord costs less than twenty dollars. Testing internal breaks is a useful skill, but not worth the risk of a fire from a bad splice.