Why You Should Label Circuit Panels
Mark new electrical junction boxes on the metal cover to avoid making several trips back and forth from the box to the panel.
When adding new electrical junction boxes in the attic, I recommend that you mark these new boxes on the metal cover with the corresponding electric circuit breaker number in the electrical panel. That way, the next time that circuit needs expanding or servicing, you (or the next person to own the home) can avoid making several trips back and forth from the attic to the panel trying to figure out which breaker to turn off. But even if you do label your boxes correctly, always test the wires before touching them!
—March Coover, Dallas
Edited and Illustrated by Charles Miller
Published in Fine Homebuilding #310