4 Things to Know About the "W" in Extension Cord Ratings

The “W” means weather-resistant A cord marked with “W” has a jacket built to handle moisture, UV light, and temperature swings better than a standard indoor cord.

SJTW is a common outdoor rating S stands for service cord (600V), J for junior (300V), T for thermoplastic jacket, and W for weather-resistant. Without the W, the cord is indoor-only.

The price difference is small, but the safety difference is large Using a non-W cord outdoors will cause it to degrade quickly in rain or sun. Paying a little more for the W rating is worth it.

Never use a non-W cord in wet conditions Running a non-W cord through a puddle can trip breakers or create a shock hazard. Stick with a W-rated cord for any outdoor use.