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.)

I normally don't work on 480, but I would never verify that the power was off on any voltage by intentionally grounding it. If it were the potential for flash/thermal burns is too great.

You also may want to read the OSHA safety standard about proper protective equipment to be used around live circuits. It also covers training.

I agree step 3 would follow step 2 because one should never fully trust a tester.

Some of our guides suggest:

1. Verify meter on energized cct.
2. Open breaker, verify cct. dead.
3. Re-verify meter on a known live cct.

I always do 1 & 2, but I must confess to not going to step 3 on 240/415V.

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'd be just as interested in live techniques here

Wow... 277 to ground live! I'm impressed...

I've never worked anything over 240V live...
I guess linemen do it every day, I just don't have the training. I've worked practically unfused service drops live, but never 277/480V...

That'll blow you several feet away if you goof, won't it? Or cook your insides...

I'm too much of a klutz to work anything over 150V to ground without some real training...

What PPE's were you using (if any)?

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.

CanadianSparky;
probably the most prevalant 3 ph is 208/120Y folowed by 480/277Y .
Virgil;
i worked for a lot of different contractors here that knew nothing of safety practices or PPE, they would simply joke that i was not to get paid for 'welding'. Some would even make up service drops bare handed. It took me quite a while to realize my upbringing in this trade was outragoeusly flawed, so don't be impressed with my ignorance.
Today if i visit similar situations i will ask the customer if he/she would like me to trace out the circuit or shut the main off, and i'll usually leave one of my computer generated panel scheduled for them.
There are, however, situations that require that i do live work. A common case in point is making on an overhead service drop, i would be interested in how others go about this.

You probably DID shut it off, but it was likely the neutral of a multi-wire ckt. that got you. This is pretty common in lighitng ckts.

I just got another of those NFPA conference mailings, for a meer $695 , and airfare for most of us, we can all learn to be safe!

My day job as an E & I Tech. in a chemical plant has a very in-depth, although not necessarily always followed, procedure manual for working on electrical systems. This policy works in conjunction with NFPA 70E. Unfortunately, it took 3 deaths before any formal policy was implemented at all.
This policy includes everything from LOTO to flash suits and designated flash-zones. Mostly, to test or diagnose anything 240 volt or below, you must wear leather gloves and safety glasses, anything over that, voltage-rated gloves, flame-proof clothing, and an arc-shield for facial protection at a minimum. This is a VERY simple overview of the policy. If anyone is interested in this sort of program, let me know, and I will send copies of our procedures.

[This message has been edited by Redsy (edited 09-11-2001).]

I won't work on anything live unless absolutely necessary.

If you do have to do, have two journeyman there only one working at a time, take turns.

Tag and lock out the circuit you are working on. Don't use masking tape use a physical lockout, preferably one with a padlock. I carry the Klein one in my truck. You would be surprised how many times somewill will attempt to energize the circuit while you are working on it. "hey my ac is out, oh here's the prblem it's shut off" no realizing you are on the roof working on it.

If you can also lock the room where the panel is. I have had jerks cut off a lock to turn on a breaker. One time a doctor did that so he could turn on his computer. Hung me up on 120 volt outlet circuit untill a fellow worker kicked the ladder out from under me. If you can't lock out the breaker and door remove the wire from the breaker.

I sometimes do a live panel change in domestic premises here to avoid a call-out from the local utility. That's 240V to ground, rather than 277V though. I occasionally work live in a 3-phase 240/415V panel to add/change circuits.

I certainly wouldn't try a big 3-phase panel change live though, or a 3-ph. outlet replacement - Too many "hot" wires with 415V between them to keep an eye on.

Ever have someone come up from behind and "goose" you while you were working on a live panel?, bump your ladder when working on a live circuit? These in themselves are good reasons to not work live. It dos'nt matter how good or steady you are if things like that happen.

I also do the "Hot" test to verify the meter [tester] works, then open the circuit and re-test.
LOTO the heck out of any and all disconnecting means, even pull fuses out of switches if there's any possible jokers .

Got hit once from 277 VAC, and it hurt plus shook me up quite bad! Glad to say only hit once [also glad to be alive today to say I got hit once!]

Canadian Sparky,
As to your question about the 347Y/600 Wye system, you guys in the "Real Great White North" [the one that Bob and Doug are from, plus the one north of Washington, Idaho, North Dakota, Wisconsin, Etc.] are the only North American country with it.
Down here, we have a 3 phase 3 wire Delta, which is 600 VAC, but the only low voltage [under 1 KV] 4 wire Wye systems are 208Y/120 and 480Y/277.

Depending on the size - in square feet - of a commercial / industrial structure, the system voltage from the utility company could be 208Y/120, 480Y/277 and upto 4160Y/2400. All this to get the required KVA into the building.
Of course, normal office lighting would be dangerous at 2400 VAC - switches would be killing people left and right!, so the better lighting voltage for large structures is 277 VAC.

Scott SET

As to your question about the 347Y/600 Wye system, you guys in the "Real Great White North" [the one that Bob and Doug are from, plus the one north of Washington, Idaho, North Dakota, Wisconsin, Etc.] are the only North American country with it.
[/B][/QUOTE]

Ah... That's something I was getting curious about too. I have several references to 347V heaters, 347/600V connectors etc. in a U.S. catalog, but hadn't seen any mention of that system in here before.

Any particular reason why Canada adopted it, or has the origin been lost in the mists of time?

Nevin:
Your point about getting bumped when working live is a very valid one. If I do have to do a live changeover, I always insist that the area around where I'm working is kept clear of other people until I'm done.

At the same time, I won't do it if I'm completely alone on a site - Just in case.

>If anyone is interested in this sort of program, let me know, and I will send copies of our procedures.

That is a kind offer. Perhaps could the webmaster take you up on it and post it on one of the forum websites?

Redsy,

Yes,
(If it would be Ok with your Employer) It might be helpful to some if We could post some of your procedures here. Let me know,

Bill

The simplest thing to do would probably be to mail you a copy of the manual to pick&post as you please. You might have to weed through some of it, but it seems to be a well-intentioned, if sometimes cumbersome, policy.
Send me an address if you want to do it this way.

Would you be able to get it in electronic form from the document maintainer?

I might. I'll try today. But, I think snail mail may be the easiest, at least for now.
I don't mean to pass the buck, but Bill would probably be better at getting it onto this forum.
Also, I have had another request, so I will see what I can do today.
Keep in mind, it is over 50 pages, including tables.
[This message has been edited by Redsy (edited 09-13-2001).]

[This message has been edited by Redsy (edited 09-13-2001).]

Well, I just tried to send the entire procedure to Bill. Hopefully, it went through and will become available. If anyone still wants a hard copy, let me know and I will try to send one.

Redsy,

Yes, I got it and it looks good. Let's see what we can do with it to make it most accessible and 'user freindly'

Bill

That's good of you to think of the safety of us all Redsy. Thanks

Any time!

After making hot-taps in a sleet storm with only leather gloves I got a genuine pair of linemans gloves, the gloves are rubber proof tested to 5kv( they do make them heavier)and a pair of leather protecctors over top.
When I make hot taps, its one at a time, very slow and I tape them first with 1 inch 3m rubber tape then two wraps of 33+. Here in my area we use Romex connectors for split-bolts too. the neutral is always last I usually shaking by then.
On one occasion, I was tying in the taps on a house that had been sided with steel and while stripping off the insulation from OEs cable, holding the hot cable in my left hand knife in the right I slipped with my left hand and it went right into the siding, burnt a hole in the siding about 1/2 inch in diameter.
On higher voltage, when I worked in Cleveland 4160 was the highest we ever worked on it was coats, gloves mask, and a dead stick to shut the power off, dead-stivk was 10 feet long, and it was still a shaky deal.

Here in my area we use Romex connectors for split-bolts too


Maybe I'm just a goody-two-shoes, but I cannot consider the use of NM Connectors for split bolts in any way kosher or acceptable. I've seen too many connections that were installed with approved means fail...

Y'all must have some really lenient underwriters... (Code? Nah, do what ever you want, we'll cover ya!)

I guess I'm the type that will go broke doing things the "right" way, though...

[This message has been edited by sparky66wv (edited 09-15-2001).]

I assume using rx connectors to splice in a service is only done in a locality where the utility follows through and makes proper connections. You should check when working in a new region, because our utility does not re-do services taps.

>where the utility follows through and makes proper connections.
Then why wrap them?
They should not be wrapped so someone will see that they need to be replaced. And they do need to be replaced.

Some years back I had heard of some guys using Romex connectors for that, then I ran across some that had been taped, and missed by the PoCo for a permanent tie. It constantly amazes me what electricity will and won't do, under almost the same conditions.

But speaking of crazy things done, years ago I re-connected a 200 amp service to a hot drop bare-handed, in a pouring rain, on a wooden ladder. I remember being scared to death, using a razor knife to skin the wire, but the boss told me to finish the job or find another.