I may be over reading this but the 4th sentence in Section 8, states:
"The main circuit breaker could protect employees from an arc-flash in downstream sections of the MCC, switchboard, or control panel if the MCC, switchboard, or control panel construction has barriers to isolate the main breaker section."

The next sentence states:
"Using the same logic, main circuit breakers in switchboards and panelboards generally are not considered to
provide arc-flash protection for their switchboard or panelboard because there is normally no complete barrier between their line side connections and the possible location of an arc-flash in their enclosures."

As you can read switchboard main breaker is referenced in the first case as possibly protecting employees and then in the next sentence as generally not considered to provide protection. Should the use of switchboard in the first statement really been switchgear instead?

On another note, it has been generally my experience that control panels with main breakers generally do not contain any barriers to isolate that main breaker.

The key point is the existence of the barriers, not the type of switchgear.

Exactly. Possibly protective, but generally not; based on whether or not complete barriers are provided. Seems straight forward to me.



There's your answer. Look to the upstream device.

If you had a breaker in a control cabinet that just had a barrier that incorporated a complete barrier between the line side connections and any possible location of an arc-flash in the enclosure, you could reduce the HRC within the enclosure? or just the shock potential?