I’ve never discussed this, but these devices are cheap insurance (not really, but you get the idea…) against all kinds of problems that can come about as a result of electrical storms. I’ve used the powered type in the past, and have one installed currently, but I came across a totally passive version that uses no power, is self resetting, and if it does fail, it fails OPEN, so it won’t cause problems. Best of all, you can get them for 30 bucks on ebay, brand new, including shipping. Just search for “LA302R”. It has 3 wires, and you simply install it in your electric box to a breaker connected to L1, L2 and Neutral. If you’re not an electrician, hire one to do this. It takes about 2 minutes. It takes longer to get the cover off your breaker box than it does to install one!!