I am the one who put the bridging capacitor across 2 single pole breakers in the breaker panel. I am also the one who reported the first capacitor I used blew up and tripped the breaker. I have since replaced the capacitor and have not any re-occurrence. The breakers i used are the breakers for my 2 bathrooms. The capacitor is the ones I bought on line from an 1-10 vendor for that specific purpose, so I assume (maybe wrongly) they are rated for the voltage.
You could bridge them across a 2 pole breaker also (like a dryer breaker) but you have to pigtail the leads into the breaker as they are only rated for one wire.
Update: 2 days ago the second capacitor blew up and tripped the breakers. Not sure what the issue is but I am going to try a different type phase coupler.