Arc Flash Studies have been around long enough that many are in their 2nd, 3rd updates/reviews.

This weeks question:

Have you found any changes to protective device settings since the last study was performed?

Yes - frequently
Yes - a few times
No - same settings as before
Havn’t revised study yet
Not applicable.

I have found a few at some customers.

Many of the changes appeared to have happened during breaker testing as opposed to being an intentional act.

Oh you mean where field changes were made. Mostly I've just found errors by the engineering firm.

Most of the settings I have had to change were due to improper coordination. It appears previous AF studies were based on solely on providing labels.

I have frequently encountered breaker settings that needed to be changed, for several reasons that are part of the nature of my employer's business (data centers). We have legacy buildings that weren't necessarily well-coordinated in the first place, inconsistencies in settings for similar equipment in the same building due to different engineers working on different construction phases, field changes during commissioning that weren't adjusted to the recommended settings... even studies with equipment that is missing altogether because we used to have a construction team in-house, who added panels as needed without making sure they were added to the study. Since our data centers are expanding quickly it seems like I always have an arc flash study to review and mark up with all of these corrections.