The standard allows different methods for working inside the arc flash boundary. Whatever energized work is performed or potentially performed, one of these methods must be used at the Arc Flash Boundary.
1. Guard (This usually entails setting another person to watch the boundary while the testing, or other work is occurring). Some circumstances might mean you can guard yourself. We DO NOT recommend this in training. You should be working, not guarding.
2. Barricade (The barricade should be at the Limited Approach Boundary or the Arc Flash Boundary, whichever is greater). The barricade is required by the standard to meet ANSI Z535.
3. Barrier (A Barrier must create a safe work zone by preventing shock and arc flash outside this area. This one is very difficult to do unless you are inside a building/room which has restricted access.
Most companies choose barricades like a red tape which says, "Danger. High Voltage, Keep Out"
Hope this helps,
Hugh Hoagland