For a shock hazard to occur, exposed energized parts are required. When such conditions exist, an arc flash hazard is present. Now the severity of the arc flash may vary by being less than 1.2cal/cm2 or greater. If less than 1.2cal/cm2 , arc rated clothing isn’t required.
There are two VERY important points to note though:
1. Arc rated clothing does not offer electric shock protection. It is not designed to impede the flow of current but rather to reduce heat transfer to skin. So it will NOT offer added benefit.
2. It is my opinion that companies having arc flash hazards sporadically across equipment should provide their workers with arc rated daily workwear uniforms. The best protection is one that is always present and always used. If your company requires workers to constantly don and doff arc rated clothing, there is the outside chance that it may be forgotten when needed.
Depends on the company policy. Is 480V exposed in the cabinet? Arc flash in 120V is typically not sufficient to ignite clothing except if the 120V is super high fault current but what else are you exposed to? I recommend AR for almost electrical work since many incidents happen when doors are opened or closed and while doing the safety check or during operation. Electricians in CAT 1 or 2 will never have a clothing ignition thus 95% of the lives are saved.