This is a great item. Not sure if I'll ever see it work, but it's good for piece of mind.
Installation was easy. I moved a double pole breaker at the top of the panel to the bottom (just extended the wires with a twist connector). The warnings about not piggybacking off of high draw or sensitive circuits concerned me, so I added 2 individual 20 amp breakers. I have plenty of extra room in my panel and breakers are only $3.50 each, so I figured it was better to have the spd on its own circuit. I also had to buy a male and female PVC adapter along with 10ft of conduit (only needed about 8 inches of it). Because of other wires coming out of the panel knockouts, I had to extend the spd to about a foot out from the panel. Hooked all the wires up, trimmed the extra wire, and restored the power. Works great, green light is on.