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Joules and Warranties

Joule ratings - the amount of energy a surge protector can sustain before failing - were designed to make comparisons easy. But they're almost meaningless except as marketing tools because, while they'll tell you when the unit will fail, they won't tell you how much voltage a protector will let through to your gear. Although Underwriters Laboratories (UL) lists joule ratings, standards bodies such as the IEEE and the IEC don't recommend using them for comparing surge devices. Instead, look at the Surge Voltage Rating, or clamping voltage, from the UL 1449 Second Edition.

Warranties are another prickly issue. While many companies offer a warranty that covers not just the surge protector itself but also the components installed downstream, the Web is filled with complaints about how difficult it is to collect on them. Many warranties contain so much fine print and so many exclusions that they're worthless. And frequently the burden falls on the customer to prove that the suppressor was installed properly and that its failure caused the damage. So read the warranty carefully to see what is really covered and what you have to prove to collect.

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