In the picture below, what is the closest distance for an unqualified worker when the equipment is open?
It should be 42" because he can wear PPE and be in the boundary. If he needs to be closer, than 42", he can get within 12" with an escort.
3. Restricted approach boundary
The restricted approach boundary is the distance from an exposed part which is considered the same as making contact with the live part. Only qualified personnel wearing appropriate personal protective equipment (PPE), having specified training to work on energized conductors or components, and a documented plan justifying the need to perform this work may cross the boundary and enter the Restricted Space. Insulated gloves, tools, and equipment are required within this boundary.
it sounds like you answered your own question. 42" without supervision but not qualified so can't go within 12. I would say the answer is 12"
1"-12" is your prohibited approach boundary
12"-42" is your restricted approach boundary
42"-48" is your limited approach boundary
48"+ is your flash protection boundary
Only qualified personnel can go in the restricted approach boundary, so unqualified personnel are limited to The limited approach boundary with supervision. Therefore wouldn't the answer be 42"?
You can’t wear PPE effectively without being trained on it.
From Fluke:
Arc flash boundary
The arc flash boundary, or restricted approach boundary, changes depending on the potential arc flash hazard. The arc flash boundary is calculated to 1.2 calories/cm2 of incident energy. That’s the distance where a worker without appropriate PPE would receive second-degree burns.
Sometimes this boundary is the furthest one from the exposed equipment, other times the limited approach boundary is the furthest out. When the arc flash boundary is the furthest away, it becomes the line no one should pass without training and PPE. If the limited approach boundary is further out, then that should be treated as the line no one should pass without training and PPE.
Answer is 12" in the practise test