What is this homeowner trying to protect against? I gather what he's really looking for is a 59 relay (overvoltage protection). You can set it to match the CBEMA curve and give way better protection than triggering a shunt-trip from an SPD that's designed only to protect against a particular type of transient condition. They're not cheap, though; I'm not sure how much they cost because I've never specced one one individually; I usually buy combo relays that cost $1000 or more.
Your other option is to bus-tap the SPD directly to the panel busbars. Since an activated SPD is a dead short, this will cause the main breaker to trip on any significant transient, no shunt trip feature necessary. I would imagine any Type 1 SPD should be safe in this application, but check the rating to make sure it doesn't require a 15A breaker or something.
I spec industrial-grade SPD on every project I do, and even put a consumer-grade whole house surge protector on my own home for $25 a few years ago, the basic SquareD 240V 3W model. [I put mine on a 30A 2P breaker.] Cheap peace of mind and yet another "best practice" that should be in every home but is rare because of nickle-diming...
Last edited by SteveFehr; 03/11/17 11:35 AM.
