under8ed
Senior Member
- Location
- Charleston, SC., USA
Two recently encountered events with breakers are worth sharing. A thermal scan performed by a contractor found a very hot phase on a newer, very respectable brand breaker. It is a large frame style, believe it to be a 400 amp. We were able to shut down the system & check terminations, but no problems were identified. When we put all back online, the problem had disappeared. I speculated that the breaker contacts may not have seated perfectly as it was likely only cycled on one time since installation. About a week later, production maintenance called us on a panel that had lost a phase since the 3 phase loads dropped. After finding the feed intact, I realized the voltage was dropping through the panel main breaker. Remembering the former event, and knowing this was also a recent installation, same respectable brand, & had only been cycled on once at the time of energizing. Sure enough, when I switched it off & on a couple of times; the problem was gone. Both breakers are being monitored, and are deemed questionable. I am curious if anyone else has run across similar problems; and if not, it may be helpful to share this.