Do we need to do Arc Flash analysis for Arc resistance switchgear since you are still exposed to bus when you open the cubicle of the switchgear.

I don't know of any arc resistant gear that allows access to the power compartments while energized.

Square D PremSet fully insulated bus, 15kv.

I remember, tThe ones I worked on had interlocks with the power panel access doors.
If the doors are open, say when they are bypassed during maintenance, the gear probably is no longer rated as arc resistant, which usually needs sealed enclosures.

Hello. My understanding the situation is not permitted with compartment door interlock.
It's better to clarify with original manufacturer and request evidence of the test condition in arc test.
I think the defined arc test in medium voltage busbar compartment is with the condition that compartment door closed.

Here is my understanding of arc resistant gear:
1. There is a maximum fault current and duration for which the gear is rated.
2. When racking in/out breakers, there is a chance of an arc flash event, but this presents no danger to the operator as long as the current level and duration is less than the SWGR rating.
3. After a breaker is racked out, the shutters are covering energized bus.
4. Because of #3, opening a door and removing a breaker doesn't result in an arc flash hazard. Furthermore, troubleshooting the circuitry in the cubicle with the shutters in place doesn't involve an arc flash hazard.

Obviously, if another person is racking out another breaker on the lineup while someone is troubleshooting circuitry, then there would be arc flash hazard to the person troubleshooting circuitry.

In my opinion, determining an arc flash hazard is balancing act that must take into account the qualifications of the people involved.