Why are UL ratings important?

The most important reason to look for the UL 1449 Second Edition Standard for Safety Transient Voltage Surge Suppressors listing is to ensure that the products are listed as complying with this safety standard. The UL 1449 measured limiting voltage ratings (let-through voltages) are determined as a part of the safety testing of the suppressor of UL 1449. This is the only data some manufacturers have because they do not have a UL 1449 certified laboratory or the staff, equipment, experience and certification required to effectively design, test and certify their products with the various ANSI/IEEE C62.41-1991 test wave forms.