what are the normal steps you take to make sure a 480volt circuit is de-energized before working on it? 1st.Open the disconnect, breaker, etc. and lock it out. 2nd.test the circuit at the point you're working at with a reliable tester. 3rd. Still making sure your hand or other part of body does not come in contact with bare conducter, disconnect it and lightly scrape it across a grounded area with your face turned away. 4. If above steps pass, work on the circuit.
How do you do it? (Always looking for better and safer procedures)
It is a good idea to test the ckt. beforehand as well, to ensure that it is energized prior to turning it off. Then test to make sure it is off.This way you are more sure you have the right one. We also attempt to re-start any control circuits prior to testing with a tester that is verified on a known live ckt. Also, look for indications that another circuit is within the same enclosure, and either de-energize that also, or remember to stay clear. (This got me once.)
much industry, even a local hospital in my area is poorly marked, tracers work badly due to long lengths running together. So for much of my apprenticeship i worked 277 ( 480 3 ph legs) live and thought it was the norm.
I used to work 277v live. no more unless I have no other choice. Years ago I once was working On a 277v lighting circuit which I thought was de-energized. I had a ballast cradled in my arms while disconnecting or reconnecting it. I still don't know what touched what but what i do know is that baby became very uncomfortable in my arms. Talk about vibrating all over! I left it drop, baby, cradle, and all. That was probably the best thing that could have happened to me since at that time I had no business messing with electric, much less 277v as I now realize when I look back. I still shudder when I think of the stuff I pulled off back then. Now many years later I have become much more educated and experianced. But I am still learning. There is always room for improvement.
If there are 2 guys, we generally: 1. Test both of our testers. 2. Each test circuit with our own testers. 3. Each test it with the other guy's tester. 4. Disconnect & cap off the conductors while working. 5. Repeat 1-3 before reconnecting. (I carry 2 testers in my box, and when alone generally use both).
Although I've changed out lots of fluorescent ballasts hot @ 277 (the only good use for a Wago), that's it! The company I now work for won't allow it. They lost a man about 4 yrs ago working hot 277V. I wouldn't think of changing a wall switch or a 480 recp hot (You should see what a hot switch to ground will do to a drywall taper's knife!)
[This message has been edited by electure (edited 09-10-2001).]
Just a quick question here. Is your next most common voltage 277/480 after 120/208? We use 347/600 mostly. But I guess thats why there so many meters that only go to 500v,sorry, alot of things just made sense to me now.