To wit, I haven’t managed it yet.

The rub is, it’s inevitable you have to mess with the damn thing when the rest of the household is thoroughly active. Interrupting power to every other circuit and appliance in the place is often simply not an option. Especially once the obligatory hardware store trip to get the new breaker – bringing the old one with you to match it up – enters the equation.

When you remove the hot wire from the breaker the wiring is by definition dead unless you have transient voltages from elsewhere that should not be there. If you do, you have deeper problems. Plus, you should do so with the breaker in question off anyway (and if you have a dud one, the only reason you knew about it was because it failed open circuit in the first place, so it’s already off). The breaker’s casing is extremely well insulated, and no part of the operation requires touching anything except insulated wire or the plasic breaker casing itself.

People also thoroughly overestimate the danger as if there are magically somehow different volts inside the panel than out of it. Yes, you can theoretically touch 240v if you manage to grab both bus bars at the same time. Otherwise, the shock you may deliver yourself is literally no different from mis-grabbing a normal plug via touching its prongs while it is partially inserted in an outlet, which is I’m sure something everyone has done at least once in their lives.

You should still know where your home’s master breaker is located anyway, of course, in case there is some other catastropic emergency.