I shut off the power to this entire house, from inside, the larger main switch at the top of the panel. 12 hours later we started hearing the garage door opener circuit board make a noise like a relay flickering. Seems it's toast upon inspection (ordered part for $60).
Would a small surge protector like the one below prevent that from happening again to another $200, 10 year old device like that?
Backstory:
We bought this home and have found some weird stuff I've yet to dig into. 50-90vac on some of the switch plate screws. Other places, 30vac still when the circuit breaker is off. Other outlets have only 30vac hot to neutral. All on one line luckily. But that's another question for another time. I will check all that out later this month.
Best Answer
The most common surge arrestors are MOV (metal oxide varistors). The one you linked will protect a single circuit but the power issues need to be fixed first or it may fry the unit (more than a 600 joule spike and the let the magic smoke out). They work by dumping spikes to ground but they are limited in the power they can dissipate. They also make larger units that can be installed to protect the entire house. breaker style I put a larger one in that required a external box and a 20a 220 breaker to feed it after that I quit having equipment not on UPS's fail. (we did have very noisy power in that house because of the industrial loads down the street).