About 1976 while working as a second year apprentice, I was replacing burnt light bulbs in an area that was a Class 1 Div 2 hazardous location. This was in the press room of a large printing plant. The Crouse-Hindz explosion proof fixtures were hanging from the ceiling 20 feet over the top of the individual printing units which themselves were 20 feet high. So... needless to says we had step ladders balanced on top of the printing unit. Never would be acceptable today... but back then it was kind of like a standard proceedure.
The problemn was that this plant used a massive bank of batteries, in the basement, for their 120v emergency lighting power supply and needless to say none of the emergency powered fixtures were identified.
So we killed all of the AC going to the other lights and tried to figure out if the one remaing to be changed was fed from the AC or the DC source. They refused to allow us to kill the DC source as half of the facility was still running.
So... I gingerly removed the heavy globe and tried to remove the 200 watt bulb... naturally the bulb came out but the steel base of the bulb remained in the socket. Oh great... I'm in a Class 1 Div 2 (naptha and toluene solvents) location balanced on a ladder 40 feet in the air with the remains of a bulb still in the fixture socket and no way to ensure that the power is off. I know... I'll get the sub-foreman and he can decide if there is power or not...
Now you have to picture this... the SF was an older gent with many years in trade, was an awesome teacher (he tought me lots over the 6 years I worked with him), had hands like catchers mits... both in respect to size and in leather content. He climbs up the ladder to the fixture... sticks his finger up into the bulb base still stuck in the socket, touches another finger on the same hand to ground, holds it for a second... then says... "nope no power there". But to be sure... he takes out his fingers... licks them then tries again... "Nope no power for sure". He then climbs down the ladder and I go up. Take my still shiny Klein's, shove them into the base to twist it out and promply blow a hole in both jaws of the pliers. Nearly fall off of the ladder and look around to see if the atmosphere in the press room had or was about to flash (plant had been down 12 hours at that point point so no explosive vapors were around).
Learned a good lesson that day... if any chance of a DC distribution system... allways check to see if one side is tied to ground or not. It was not. I still have the Kliens with the holes in them.
Edited for spelling...
[This message has been edited by Rick Kelly (edited 10-08-2006).]
