Here`s how I did it:
Make sure that all the circuits have a load: turn on the lights, plug in appliances, what have you.
Turn off the main cutoff in the service entrance box. (Turn off your computer first.)
Turn all the individual breakers off.
Remove the dead front, the metal panel that covers the wiring to the circuit breakers.
Disconnect the neutral wire of interest from the neutral buss
Clip one lead of an ohm meter to the neutral.
Now probe the hot wire
connection at each breaker. Most will read out-of-range. The hot wire
matching the neutral will show some resistance. (In my case, about 450 ohms.)
Tedious and disruptive, but it worked for me.
When I restored power, I left the heavy loads, like the air conditioner and water pump, toggled off, then activated them one at a time to avoid a huge inrush.