LOL at an IBM facility!?! That's priceless, they were known for running a ridiculously tight ship and letting you know about it constantly. I wonder how many of their engineers had eyes on this and it still made it past the goalie...I agree a coordinated study may not have been done and the setting was too low on the main.
I took out a 400 amp breaker and a 7 pole contactor with a short on a 20 amp circuit at an IBM plant in ny
They certainly have a coordination issue.Short circuit on a 20A lighting circuit and it shut down the whole building!!
What would have caused this to happen? Why did none of the other breakers in the series trip?
Guessing the trip settings on the existing main were dialed down way too low?
Needless to say, my guys had a stressful morning/:biggrin: