277 volts on one phase

[user 100]

I have been shocked many times, almost every company I have ever worked for we did a lot of things hot,also rode company trucks that the seat belts did not work and on the way back to the shop drinking like a fish,that's just the way it was at those certain shops. I had a job and that's all that matterd at the time,you guys are bashing this young man for asking a simple ? ,regardless the voltage he knew it was hot,and I'm sure he worked on it like it was hot, his EXP might only be in low voltage residential guy, but he has the concept to ask about something he did not fully understand,it's just a lighting fixture he felt comfortable doing it one hot one neutral 277 or 120 disconnect it one way reconnect the reverse way simple.some people on here are acting like his Forman told him to do a line side tape live,it was a lighting fixture,hopefully he does not lose his confidence do to all the negative feed back

I don't think anybody here was picking on the guy. They were only trying to impart the dangers of working/troubleshooting hot and they did a pretty good job explaining it to him-They simply don't want to see anybody get hurt or worse.

 

[Shawn pavich]

He knows how to disconnect and reconnect,he explained it to everybody, they were bashing him because he put his pride aside and ask for direction, on something he did not understand,I'm kinda scared to ask a question on this site.if I ask the wrong thing are you guys gonna have the gang up on me and make me question my choice of work my career, believe it are not this is not tho only electrical forum around

 

[Shawn pavich]

And for the guy that said he would rather have paco save his life then EMT.Why cause paco has you said better equipment lol

 

[kwired]

And for the guy that said he would rather have paco save his life then EMT.Why cause paco has you said better equipment lol

That is not what I said. I simply said I would feel lucky if one of our local POCO guys was one of first ones to come upon such an incident. Better yet would be if an emergency room physician just happened to come upon the scene, but I think the chances of having a POCO truck come by are a little higher, especially out in the countryside. I did not say the POCO had better equiment then the EMT's either. I said they have good first aid/emergency response training and compared to average motorist on the road they probably are some of the best around when it comes to knowing what to do if they come upon such a situation. They also have two way radio's in their company vehicles and can contact not only their dispatcher in an emergency but other company employees that may be nearby can hear the calls and will come to help.

Comments about working things live are intended to open one's eyes to reality of what can happen, even if they seem a little harsh. Many have been killed working on 277 volt luminaires. If you were tasked with fixing a light and knew this was going to be the one that gets you, you would turn the circuit off wouldn't you? It only takes an instant and there is nothing you can do about it - then you are dead. I admit to having done such things myself, but you still need to preach what it right or it will never be seen as unacceptable. 120 volts is more forgiving, but you still don't know when conditions will be just right for the worst outcome.

I am glad the OP did ask about something he did not have any experience with, but the way he described things he acted like this was some new discovery or new technology that has just been put out, but it was only new to him we were only trying to educate him that he has found something he doesn't know much about. 277 volt lighting is far from new technology.

OP can either listen and learn or continue to ignore and put himself at higher risk - he has a choice.

 

[growler]

I just have discovered the concept of something more than 120 being on one phase. I have been doing electrical for years, but didn't have any commercial experience until the last 3 years.

At work today at a store.

I was making boxes for the new light fixtures that would replace the previous cans.

I noticed at the junctions they were marked 277V
I said to the foreman that they must be marked wrong. I have worked with 3 phase, but it hadn't really seen certain aspects of it, or realized that they can be on one phase.

He said all the lights were 277V. Which I then realized why my circuit breaker finder didn't work on them, as I suspect it is only rated for 120V

There are so many lights in that store, and it is big, they need 277V fixtures.
He said, wait to you see 480 on one phase.

Tomorrow I think I will use my meter on it, just to see 277V on a hot and neutral.

they were bashing him because he put his pride aside and ask for direction, on something he did not understand,I'm kinda scared to ask a question on this site.

What exactly is the question asked by the OP? I don't see where he asked for any direction at all.

 

[growler]

if I ask the wrong thing are you guys gonna have the gang up on me and make me question my choice of work, my career.

Do you mean that you have never questioned why you chose this line of work?

I have questioned my sanity many times.

I like to think that I could have been a "Lumberjack"

This is where we start the Lumberjack song...... I'm a lumberjack and I'm OK

 

[kwired]

What exactly is the question asked by the OP? I don't see where he asked for any direction at all.

You are right, there isn't really any question in there. It is presented as if he can't believe that voltage over 120 to neutral even exists though. To me this just means he has never seen such a thing before, but many of us see it all the time and realize it is fairly common.

Someone needs to tell him that 480 volts to some is considered low voltage and that 12.47 kV is considered medium voltage. He only works in his small corner of the electrical trades. I only work in my small corner as well, but have tried to learn as much as I can about things and feel I have enough general knowledge to step into most anything out there and not be totally in the dark even if I have never seen it before.

 

[growler]

It is presented as if he can't believe that voltage over 120 to neutral even exists though. To me this just means he has never seen such a thing before, but many of us see it all the time and realize it is fairly common.

The fact that an electrician has not worked with say 480V three phase I can accept as being normal. Many residential electricians have never worked with these voltages but to be unaware of there existance is another matter.

I don't see how you can do electrical work for 15 years without hearing other electricians talk about working with 480/277V.

 

[kwired]

The fact that an electrician has not worked with say 480V three phase I can accept as being normal. Many residential electricians have never worked with these voltages but to be unaware of there existance is another matter.

I don't see how you can do electrical work for 15 years without hearing other electricians talk about working with 480/277V.

And especially never running into a little of it after 3 years of being mixed into at least some commercial work.

Rules are essentially same for 208,240 or 480 volts, just voltages are higher.

There is an occasional item added that may apply to 480 volts that doesn't apply to 208/240 volts, but most general stuff is the same for anything under 600 volts.

 

[ActionDave]

I'll toss this in just to add to the discussion.......

Talking with a lineman about an accident my boss was involved in where a 480V safety switch blew up when he tried to close it. The only thing that kept his head from getting blown off was he tripped when he was trying to shove the handle up.

Lineman shook his head and said how much he hated 480. He would rather work on 13,000 on up. "Why?", I asked.

He said the worst voltage level to deal with is 480 because of how well it sustains an arc.

 

[kwired]

I'll toss this in just to add to the discussion.......

Talking with a lineman about an accident my boss was involved in where a 480V safety switch blew up when he tried to close it. The only thing that kept his head from getting blown off was he tripped when he was trying to shove the handle up.

Lineman shook his head and said how much he hated 480. He would rather work on 13,000 on up. "Why?", I asked.

He said the worst voltage level to deal with is 480 because of how well it sustains an arc.

Couple other factors make medium voltages somewhat safer assuming you are practicing some fairly common safety procedures.

Most of the time they are switching components that are 25 -30 feet off the ground, and are using a long stick to operate those switches. If it does "blow up" they are a fairly safe distance away. Also if it does blow up in relatively free air - the blast can go all directions, lower voltage gear is enclosed and a lot of the blast that was not directed at you is reflected back at you.

If pulling/installing fuses on a padmount - you have more enclosed equipment and more risk of majority of blast being directed at you, but you also have a long stick to put some distance between you and the gear, as well as add more insulation between you and the 7200 volts to ground.

The one rural POCO that I work around the most has design specs that puts their primary fusing on opposite side of pole from a meter socket for those installs that have a meter on same pole as the transformer bank. The reasoning is (and is especially for 480/277 applications) is they don't want a lineman trying to close fuses with a extension stick to be standing in front of the meter/disconnect should there be a fault when they energize the line and it causes an arc blast within that meter/disconnect. You learn this if you are burying conduit to a pole that doesn't have a meter on it yet - they want it on a specific side depending on how it works out with the cross arm and fuse mounting hardware. They want fuses on same side as cross arm, transformers and meter/disconnect on opposite side.

 

[meternerd]

OK...hurt feelings. Well, as an electrician who hasn't seen everything out there that there is to see, I value input from those who have more experience than I do. Just might keep bad things from happening. The trade we chose is so varied that there are really no experts...just those who have been around things we haven't. We all want to go home at the end of the day. The only bad mistake is the one that teaches nothing. Like the wise old "somebody" said, "Experience is usually a mistake you live through." Education is just confusion at a higher level. Just a few sayings I still remember. All I can add is...Never Stop Learning. OK....done preaching. Remember, there are a lot of people besides the OP reading these threads.

 

[kwired]

Remember, there are a lot of people besides the OP reading these threads.

Right there, many that never reply read things said here, and I'm sure many that only read stuff learn a lot here.