When our guys close a 480V (or sometimes more) CB or switch for the first time, they always gear up in arc-rated PPE. It got me wondering: How often do they flash the first time they're operated, and why? Our guys say they've heard of it happening, but I don't know anyone with direct knowledge of it. Manufacturer's defects seen unlikely, given the testing these things undergo before they're put under load. A couple of the guys suggested they blow up because tools and debris might have been left in them during installation. Thoughts?