Many homeowners look at Joule ratings to determine which surge protector to purchase. Unfortunately, Joule ratings can be misleading according to IEEE research. When a surge protector is submitted for third party testing with Underwriters Laboratories (UL), a Joule rating is not a tested parameter. Joule ratings are an unreliable measurement for determining a products surge capacity because there is no test standard. The Joule rating listed on a surge protector’s package is determined using an unknown method by the manufacturer.