Pete C. wrote:

Suggest you call around and as any licensed electrician if they turn off
the main breaker when replacing a branch circuit breaker (unless the
breaker being removed is physically damaged of course). Suspect you
won't get a single affirmative answer.

I'm a licensed master electrician in two States with 30 years
experience, doing mostly large commercial and industrial. I supervise
10 to 20 experienced journeyman electrician's. I can assure you that I
de-energize _all_ electric equipment when possible. I encourage all
electrician's on my crew to de-energize all equipment, use PPE, and
lockout/tagout. If it is an inconvenience for the customer, we will
schedule a shutdown. Sure, electrician's work stuff hot, but not
without assessing the hazards, taking precautions, using PPE, having
people around (and who stay far enough away) who are capable of
rendering assistance should something happen, etc. I do not permit
inexperienced electrician's to work anything hot, period. In this
newsgroup, with mostly inexperienced people doing DIY, IMHO it is
irresponsible to tell folks to work _anything_ hot.

Anyone who has done any amount of electric work knows that a lot of
work is done hot without PPE; it's just the nature of the beast.
However, I can tell you plenty of horror stories about how
electrician's and others have been seriously injured working electric
equipment hot. Part of being qualified to do electric work is being
aware of the _hazards_ that exist. I personally am amazed at the
number of people who are aware of shock/electrocution hazards, yet have
no idea that there is also an explosion hazard.

One thing is for sure, should one make the personal decision to work
electric equipment while it's energized, should an accident happen, the
_first_ thing that that person is going to hear from someone ( _IF_
he/she is still alive and _IF_ he/she can still hear or see) is:' You
should have de-energized that equipment."