I have used that " bulb trick" a few times to get myself out of a jam troubleshooting in some of the older apartments with plug fuse panels..
When you think of it, if you have a H-G fault big enough to open the OCD, Then I would think the ground path would be sufficient to carry a few milliamps from a 40W or 60W lamp screwed into the panel while you do your troubleshooting... I agree it may not be ther safest thing to do, because everything is still going to be "live" but it does work... Last time I used this trick, I narrowed the problem down to a faulty " multi outlet" cube tap in a back bedroom... Would have been there hours checking everything on the circuit thinking it was in a box somewhere... Had the call done in 1/2 hour and left the place with a very happy tenant as well!
A.D
