“In determining the arc flash boundary zones in your electrical rooms, do you make any allowances (provisions) for permanent, existing barriers, walls, obstructions when using remote racking systems to rack in/out breakers”? In other words, do you allow personnel to reside behind a permanent barrier when remotely racking a breaker wearing a clothing category less than that specified for the IEEE-calculated energy at barrier’s distance from the equipment. This pertains to calculated arc flash boundary distances that extend beyond the block wall of any electrical room.”

I generally consider anything substantial (masonry, steel, etc.) Based on thermal process experience a great heat shield to get from continuous ambients of 600-800 degrees down to under 120 degrees is nothing more than 1-2 pieces of sheet metal siding separated by a 1“ spacer for the 2 layer version. Not saying this is effective for arc flash but gives you an idea how little material is required for purely thermal concerns.