TVSS Specifications & Selections

There are several hundred TVSS devices available for purchase. How can you tell if the one you have selected is a quality device?

Make sure the device is United Laboratories (UL) listed as TVSS or Transient Voltage Surge suppressor. Also, make sure that it meets UL standard 1449, the number of the UL test for TVSS devices. Both of these pieces of information will be shown on the UL label. Some equipment sold as surge protectors are not listed as TVSS, but are instead listed as a ~~current tap." These devices will have the word TAP near the UL label and should be avoided for use as a TVSS. In addition, the UL label should list a clamping Voltage of 500 volts (.5 kV) or less for plug-in TVSS, or commensurate with your service voltage on hard-wired TVSS. The lowest clamping voltage recognized by UL is 330 volts (.33 kV).

The TVSS should have an operation Indicator in the form of a light or audible signal. This lets the user know if the device has tripped or gone bad, and the circuit is no longer protected. Most good quality TVSSs will work for years without problems.

It should have at least a one year manufacturer's warranty. Hard-wired TVSSs should have the manufacturer's schematics describing the components. The device should provide protection: line to neutral, line to ground, and neutral to ground. It should provide a fuse or circuit breaker for overload protection, and thermal overheating protection. Finally, it should provide additional protection for "backdoor" surges if needed. These would be for telephone line, coax cables, and the like.