The Myth of Whole-House Surge Protection

How Do Filters Work?

Powerline surges consist of a brief burst of high-frequency energy. The power frequency is 60 Hz. Surge frequencies are 20,000 Hz and higher.

A filter that removes the surge frequencies will eliminate not only the surge but also the associated noise. Removing powerline noise has the added benefit of improving the quality of the A/V signals.

Filters work continuously. Unlike shunt mode clamping circuits that do not begin to suppress a surge until the clamping level is exceeded, the continuous operation of a filter can be much more effective.

In fact, modern Power Quality Filters have been shown to filter and cancel out surge voltage to such an extent that protected equipment will be unaware a worst-case surge event has even occurred.

Couple this with a 10-year life for point of use applications, and you have a worry-free, noise free, maintenance-free electrical environment.

Safety Certifications

Underwriters Laboratories has a UL 1449 Safety category for "Surge Protective Devices" (SPDs). This covers the older shunt mode technology.

Filter technology is covered under UL 1283 "Electromagnetic Interference Filters."

Meanwhile, Modern Power Quality Filters under UL 1283 can be effective and reliable at surge suppression. They operate over a wider voltage range than products called Surge Protective Devices (SPDs), which are under UL 1449.

Rudy Harford is chief engineer at Zero Surge Inc. He holds over 40 U.S. patents in the field.