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Old 10-04-2007, 08:50 PM   #1
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Hi;
I am curious as to how many electricians and DIY'ers do wiring on the breaker panel while live.
I know it is neither recommended or safe, but sometimes I just feel a little more bold than at other times.

I used to cut the mains whenever I installed or removed any breaker, and always when installing or removing wiring from the box.
However, recently, I have to admit that I have been doing some work on the panel while it is live.

I use the one-hand rule: One hand is always in the pocket while the other is doing the work.
Also, I normally wear safety goggles, just in case there is an arc, and there is any molten copper splashing towards me.
I have never had an incident working live, and have never had one where I was working on a dead panel and made a mistake that would have been an accident on a live one. Then, I don't work on these things every day.

I know that the "right" thing to do is cut the power, but I think as we gain more experience, we also gain more confidence, which can be a good thing or a bad thing.

From what I have seen, most commercial electricians work live whenever possible, as we all know what shutting down a bank of computer servers will mean to the company<g>

I have talked to people who say they don't even kill power when installing a switch or receptacle! Now that takes some very skillful work, especially if you're working with metallic boxes.

I recall once at work our "electrician" was pushing a metallic fish tape through a large conduit, and went a bit too far. The tape made contact with the mains. It created a loud explosion, and knocked out power to the entire plant.
The electrician was OK.

FW

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Old 10-04-2007, 09:11 PM   #2
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Mean ol Mr. Electricty is invisible until you touch it..

People who do what you are suggesting and continue to get away with it develop a sense of complacency and/or confidence.

Do you really wanna bet your life just so somebody's cornputer wont get shut down while they are playing solitare in thier office cubicle?

Shut down the panel and lock out/tag out. If you plan your work it will only be down a short time.

If you dont, you could be down for a long time. [like forever]

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Old 10-04-2007, 09:38 PM   #3
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Originally Posted by Sammy View Post

Do you really wanna bet your life just so somebody's computer wont get shut down while they are playing solitare in thier office cubicle?

Shut down the panel and lock out/tag out. If you plan your work it will only be down a short time.
If only it was that easy, you can't just walk in and tell people you are tunring off there computer. If you want to do this you will be working the graveyard shift.

if you work with electricity everyday you build up your confidence and skills and have no problem working on panels that are live.

If you have put on 100's of plugs and switches it is very easy to do it live. Once the wire is on you wrap it in black tape and you don't have to worry about it shorting to the box when you put it in.
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Old 10-04-2007, 10:35 PM   #4
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If only it was that easy, you can't just walk in and tell people you are tunring off there computer. If you want to do this you will be working the graveyard shift.

if you work with electricity everyday you build up your confidence and skills and have no problem working on panels that are live.

If you have put on 100's of plugs and switches it is very easy to do it live. Once the wire is on you wrap it in black tape and you don't have to worry about it shorting to the box when you put it in.

Spoken like a man who knows what he is talking about. OSHA has taken it out of our hands and as corporations are educated by their lawyers you will find in the VERY NEAR FUTURE that it will be much easier to have equipment shut down while working on it. Can I install virtually anything live? Certainly, but Google "arc flash" and "arc flash injuries" and you will find out why(besides the fact that it is against company policy) I do it less and less. Often times electricians are killed of disabled FOR LIFE thru equipment malfunction, carelessness of others out of their control, and environmental hazards out of their control. As a DIYer anyone at anytime works anything hot is doing a great diservice to their family.... I really can't state this strongly enough!!!!
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Old 10-04-2007, 11:01 PM   #5
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I think that a lot of it has to do with the fact that often when you shut down a panel, the lighting around it goes out as well.
I have a good headlamp that I love to use. It's a climber's lamp, so I don't get any head protection with it<g>
Rock Climbing... now you want to talk about something that is dangerous?

I don't feel that I am becoming complacent. It's just a little more convenient to work live.

Sometimes, it is the mere fact of knowing that the panel is live that causes you to make that big mistake!
I think of walking over a high bridge which does not have hand rails or barriers.
Sure, I can do it. But my brain would tell me that I am going to fall, so I wouldn't.

So I have to ask myself why I have been doing any live panel work.
I think that I will end that practice here and now.
I will just schedule my work so that I can do it with the least interference.
When it comes down to common sense, I always pride myself in having a lot of it, yet I do things like this.

I suppose there are ways to minimize the risk if you HAVE to work live. I thought of using some sort of flexible plastic shield to cover the live areas while you work in the box.

Thank you for your input to my question. I think what I have read here has forced me to reconsider my choices.

FW
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Old 10-04-2007, 11:08 PM   #6
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I'll say this one time if you are working live in a commercial (outside of trouble shooting) environment in the USA you are about 10 years behind times. OSHA would not blink an eye for a split second fining your company if they were investigating a compliant for live electrical work. You do not work live!! Anyone working live is working with a company that has no clue of the federal requirements for live work. You do not install receptacles live nor do you install anything on live circuits. If you do... you risk death... be it 120 volts or 480 volts. BTW there are more deaths with 120 volts than any other line voltage.
Anyone that still believes in the one hand rule simply loves to believe in myths. Hearts stop beating from only milliamps of current. Current seeks all paths to ground if that ground is available. If you're that path to ground the current and voltage could care less how many hands you have in your pocket.

In residential work (outside trouble shooting again) there is no reason what so ever to work in a panel with the mains still in the "on" position. In fact it should go to the off position and then your guard either factory or field made should be installed over the mains.

If that electrician at your plant would have had a guard in place he would not have made contact with the mains fishing that tape. These are poorly trained electricians or stupid ones.

I'm a little opinionated in this subject being a union tradesman. Historically the IBEW and other skilled trade unions spearhead safety in the work place. So that an employer cannot put you at risk...you see he will go home to his family...and you may not. And please no one even start with that real world excuse or they will fire me bs. If I worked for a company that ignored the osha regulations in a commercial plant and expected me to work live there would be a real quick issue. If they fired me for refusing to work live they would be some awfully ignorant supervisors....for not realizing the consequences of such an action. In the trade unions we lost a lot of electricians to live work,... their families never to see them again. It was workers that got the safety regulations in place not the companies. So all I can say is... be it residential or commercial or industrial you do not work live !

Oh and by the way if your working live and the company has policy to the contrary (they should) your family will not get a dime of your insurance if you die working live against osha and company policy.

If your company has no lock out tag out procedures then you best sit them down and catch up with the rest of the world.

Lock out tag out is for all companies not just union and is state and federally mandated.
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Last edited by Stubbie; 10-04-2007 at 11:20 PM.
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Old 10-04-2007, 11:34 PM   #7
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Let me tell you somthing that really can be somehow sligty graphic but let me expain from my experince with this electric shock i did survied that voltage was 600 V DC i was working on the generator have proper LOTO producres [ locked out tagged out ] somehow someone was idiot bypass this safety podcure and i got zonked with full 600 volt from nowhere.

how much i hurt ?? pretty good damm hurt [ i can used the other words but i rather not to in here unless someone can speak in fluent french then they can understand this ]

slightly damaged arm stil using my arm very well but sore little muscule damaged allready heart was out of wreck for short while just feel like a semi truck slam on your chest.

that happend many years ago.

so my simple rule try not to work on hot if possible and if can work at diffrent hours that will be a better choice unless it is a 24/7 place then specal produrce will be ineffect [ i will not expain the details here for safety reason ]

Merci, Marc

sure i got hit with 277 v as well that is nasty as well

Last edited by frenchelectrican; 10-04-2007 at 11:38 PM.
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Old 10-04-2007, 11:38 PM   #8
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In my case, I work only in residential, and then it is only home or family members.
I don't know why I sometimes worked live. It's not any sort of defiance, or overconfidence with me. I think it's more that I just don't want to cause a fuss with everyone when I shut the power off.
I realize that this thinking is stupid, and could get me seriously injured or killed. Then everyone would be asking themselves why I didn't shut off the power.

This is something I have done only a few times, and will do no more.
As far as the guard for the mains; Where do I get one, or what would you recommend in making one for myself?
In the box at home, the terminals and screws are still exposed on top of the mains. I never have liked this. Some of them have the shroud already installed.

FW
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Old 10-05-2007, 12:08 AM   #9
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In general only a few companies have factory guards available. It is best to make them in the field based on the panel your working in. I've made them from wood, cardboard and plastic. BTW don't go using steel tapes to get your measurements..... In our plants we had guards for every panel...made most of them in the shop out of 1/4 inch nylon stock and they were either laid in the panels bottom gutter (when possible) or close by the panel for ease of use. Now I realize that not everyone as a homeowner is going to do this but it is an excellent idea if you feel your going to be in your panel(s) very much over the years. Then sometimes we have the luxury of a isolated main disconnect ahead of the dwelling panel....that makes things nice and safe.

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Old 10-05-2007, 04:40 AM   #10
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I worked as an insurance adjuster about thirty years ago and investigated a case where an electrician was working live with 480 V AC. It was in a University bldg. and they didn't want to shut down the computers. The electrician mistakenly used too long a bolt and made contact with the ground through the hot buss bar. It resulted in a flash which caused severe burns to his face. I visited him in the hospital. He face was permanently disfigured. He was lucky that he wasn't killed.
In reading the original posting, I'm beginning to wonder if this person is for real, or maybe this is an alias for the baloneyman?
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Old 10-05-2007, 01:01 PM   #11
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After I'd finished my apprenticeship, I got a construction job at a power station (1984). One day, the foreman asked me to disconnect the power from one of the demountable offices because it was being relocated.

I located the fuse board that supplied the office distribution board. The fuse board was in a small room that was always locked. There was absolutely nothing in that room besides the fuse box.

Anyway, I removed the fuses & put them on the floor (I should've taken them with me), left the room & locked the door. I then went to the distribution board & with a voltmeter, checked each phase to earth for voltage. As expected, they were all as dead as doornails.

I had loosened the incoming 3 phase feed to the main breaker & as I was pulling them out (they were all cable tied together), spring tension caused the cables to spring together.

BANG!!!!!!

All I saw was a big green dot & nothing else. Basically, I was blind.

Anyway, I got taken to hospital & was treated for 'flash'. I had a total of 2 weeks off work...for 1 week, I couldn't see at all & it took another week to regain normal vision. Even to this day, I suffer constant conjunctivitis...very uncomfortable.

Here's what had happened.
A labourer saw me leave the small 'fuse box' room & decided he wanted to see what was in there so, with a screwdriver, broke into the room. He then proceeded to replace the fuses that I had removed.

He was sacked the following day.

After this incident, if I have had to work on equipment that was isolated elsewhere, I've posted a guard to make sure that nobody plays with things they shouldn't be playing with.

There is only one reason for working on live electrical equipment & that is stupidity!!!
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Old 10-05-2007, 02:13 PM   #12
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Here's a good reason not to work live.


Do a web search and you'll find out just how disfiguring an arc flash can be -if you live and aren't blind you won't want to look in the mirror.
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Old 10-05-2007, 08:05 PM   #13
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Here's what had happened.
A labourer saw me leave the small 'fuse box' room & decided he wanted to see what was in there so, with a screwdriver, broke into the room. He then proceeded to replace the fuses that I had removed.

He was sacked the following day.

He should have been more than sacked! Couldn't you have filed a lawsuit?
When I was in High School, there was a kid in my electronics class who was the victim of an arc flash. He had been working with his dad on a live 480V panel. He spent many days in the hospital while surgeons picked copper out of his face. Luckily he was wearing glasses, else his eyes would have been gone.

I think I have been convinced. I will NEVER work live again.

FW
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Old 10-05-2007, 08:31 PM   #14
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So, is an arc-flash what results when say a piece of copper wire gets shorted between the 110V bus and ground in a breaker panel? This is apparently what happened to my old school mate.
From what I have been reading, an arc-flash is a lot more than that.
That is not to downplay the danger of working on 110/220V panels though.

I watched the video to which jogr's link pointed. Quite impressive, and very scary!

FW
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Old 10-06-2007, 10:21 AM   #15
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Quote:
Originally Posted by fw2007 View Post
So, is an arc-flash what results when say a piece of copper wire gets shorted between the 110V bus and ground in a breaker panel? This is apparently what happened to my old school mate.
From what I have been reading, an arc-flash is a lot more than that.
That is not to downplay the danger of working on 110/220V panels though.

I watched the video to which jogr's link pointed. Quite impressive, and very scary!

FW
An electrical arc is the result of either;

1] a higher than usual voltage usually as a result of a switch opening (back EMF). This high voltage ionises the local air particles, which then conduct electricity & sustains the arc. (Arcs are usually current paths to earth).

2] an electrical fault caused by either a phase to phase or phase to earth fault, although this kind of fault may not necessarily sustain an arc.

In either case, the most important thing is the "Prospective Fault Current", which is the amount of power a transformer (for example) can provide under short circuit conditions. Most general power distribution transformers in Australia (the ones on the power poles) have prospective fault currents of between 20 000 Amps & 50 000 Amps.

As an example, if you were to attach 2 wires to each pole on a 12 volt car battery (100 Amp/hour) & then touched the wires together, you would get a spark.
Do this same experiment with twenty similar 12 volt car batteries connected in parallel (2 000 Amp/hour) & you would get a significantly larger spark...probably molten copper in your hands.

So please don't assume that voltage is the important factor here. It plays a part but Prospective Fault Current is much more significant. Have you ever wondered why circuit breakers have something like "10kA" on them? The 10kA means 10 000 Amps.

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