What exactly are the allowable clearance distances for bus plugs. On our 2000 amp bus the plugs can be installed top or bottom mounted. In parts of our plant, if top mounted, you would not have 42 inches of clear space. (The ceiling would be within that distance). Also, on our 400 amp and 600 amp bus we have clearance problems because of the way they were installed 45 years ago. Almost all of the bus has one side facing the truss in the ceiling, or has other obstructions within the 42 inch limit, like fire sprinkler systems or old steam lines. These bus plugs are not items that get serviced or require much maintenance while hot, so do they have to have the clearances that floor mounted panels would need. Thanks in advance.