Pghwireman wrote:
The rating of the main breaker line side(81) is calculated at a Dangerous category. The load side bus is calculated at a Category 3 rating. The feeder breakers off of this bus are rated Category 2 & one device is rated as a Dangerous category. The substation bus is contained with in barriers within the gear. Removing the rear covers exposes only the load side terminals of the breakers.
I am confused about your 82.5 cal/cm2 on device #83. 82-89 should all be about the same
Pghwireman wrote:
How would you label this, specifically Sub 5? I think this could play out a few ways. Do you label all breaker cubicles at a HRC 3 level since they are connected to the bus? Would you label the rear covers with the HRC 2 level since that is all that is exposed (load side of breakers) when the covers are removed? Your thoughts?
Where do you get HRC 3 from? Having different labels on the front and back is fairly common. Have you considered mitigating these? Easy fix for sub 5 (Besides the main) is retrofit the main with a trip unit that has arc flash reduction capability. We do those every day. The main breaker and the transition section on the 480V side of the transformer is tougher but I have mitigated that down to HRC 1 at a few plants.
Sounds like they have the racking figured out, what about operating the breaker before racking? Have a solution for that one yet?