Hi Steve,

Many years ago, down in South Louisiana, I worked at a security company (alarms, access control, surveillance, etc.), which used both dialup and dedicated circuits to connect our field equipment to out central station. Thunderstorms are more than common in South Louisiana. Despite using MOVs and whatever other kind of transient suppression we could find, repairing lightning damage was a significant part of our routine. Then I found a device called a gas discharge tube which all but eliminated our problems.

This was back in the early 1980s, and I'm sorry that I can't tell you where to find such a beast today, but I can describe the device to you and hopefully someone will know where to find one today (assuming they're even still made). The device consists of a three leaded package, cylindrical with two axial leads and one radial lead. The body is approximately 0.5" long and of a similar diameter. Electrically it is nothing more than a hermetically sealed dielectric gas-filled cylinder with the three leads forming electrodes that are electrically exposed to the gas but isolated from each other.

It is installed by connecting the two axial leads to tip and ring of the phone line, and the third (axial) lead to ground. During the surge of a lightning strike the gas ionizes and conducts to the ground lead.

The difference these things made for us was nothing less than phenomenal.