6 Things to Know About Extension Cord Ratings

SJTW is the best all-around rating for home use It covers indoor and outdoor use, handles heavy household tasks, and stays affordable. The code means service cord (S), junior 300V rating (J), thermoplastic jacket (T), and weather-resistant (W).

The J means 300V, which is fine for home use You do not need the full 600V rating from cords without J. Junior-rated cords handle everything from power tools to holiday lights.

The W means weather-resistant, so look for it W protects against UV and moisture. Without it, the cord is indoor-only and will degrade outside.

SJTOW is overkill unless you work with oil The O adds oil resistance. Skip it for general yard and garage use.

STW and SO are for industrial or long runs These are thicker, heavier, and more expensive. You only need them for high-draw equipment or runs over 100 feet.

SJO is fine indoors but not for rain It lacks weather resistance. Use it only in dry, indoor spaces.