Electrical Safety

[Geo-TH,In]

There has been a lot of talk about linemen getting electrocuted.

After I grabbed a hold of 440v 3 phase I decided not to trust my test equipment with my life. I will use meter first to see if power is off, then I use two screwdrivers and short power to ground. Shorting power to ground has removed the tips of a few screwdrivers, but I'm still alive.

I know a man who thought throwing the breaker would turn power off. Good thing he was working on a roof air conditioner at a hospital and two heart specialists were there. He was pronounced dead a few times. Lost a finger over the deal. They are guessing lightning fused the circuit breaker contacts. Thinking the power is off by tripping breaker just about killed the man. He now jokes he can only give you a hi-4, instead of a hi-5.

I was helping SIL remodel kitchen. I asked if he turned power off, yep. Then I grabbed the insulation on power wire and touched it to the neutral. A big snap and breaker tripped. It scared him. I just laughed. It was a good lesson to teach the boy, short out wires before getting a hand full.

How many short power wires to ground before grabbing the wires?
geo

 

[Steve@Advance]

That 440v hurts, don't it!

I've never grabbed it, but I brushed the back of my finger against it, reaching up inside a spot welder. I thought the area I was reaching into was all control voltage, it wasn't! It burned a small blister on my finger, but the pain was the same as smashing it with a hammer! It hurt and throbbed for hours!

As for trusting a breaker or disconnect, I nearly got in trouble with an old 240v 3 phase disconnect. It had some type of paper/phenolic arms inside that moved the contacts when the lever was pulled. The center arm (high leg of course) was broken, so when the lever was pulled, that leg stayed energized! For whatever reason I decided to take a look, guess it just didn't feel right. Sure enough...

 

[Geo-TH,In]

Steve,
Lets say 440 will make you vibrate at 60 hertz for hours and it hurts.

Now for an electricians joke. Man tells his wife when she turns 40 he is going to trade her in for two twenty year old girls. Wife just laughs, tells her husband, You aren't wired for 220.

Be safe, short your wire before grabbing a handful.
If I were in a coffee shot, I could see where this conversation would be heading. Better not go there.

 

[MarkB_MI]

My son is an electrician. A while back he re-wired our electrical service hot. Before reconnecting the incoming overhead lines, he touched each one to the cable to which it would be connected to make sure they wouldn't arc. I noticed he turned his head away from the wires just before he touched them, and I asked him about that. He said if you see an arc when you're standing on a ladder, there's a good chance you'll fall off the ladder.

 

[K Effective]

I will say that working at a power plant has taught me more about electricity than any other experiences I've had. We routinely rack 4kV breakers in and out of their cubicles- requires full 65kCal flash gear and 10kV gloves, 600V breakers get lighter weight gloves, but still full flash gear. I cannot reach inside a 600V breaker bucket to reset a thermal overload without the same protection. Our electricians use a Live-Dead-Live process to check any circuit before working it unprotected- proves the meter works before and after the voltage test. And we hang lots of grounds, that's the only time I can reach into a breaker cubicle unprotected, is if grounds are installed and verified.

It carries over to home, I never wore gloves like I do now, nor safety toe boots, either. And, I now use some form of lock-out system whenever doing electrical work, and ALWAYS verify a line dead with a tested meter first! About the only thing I work hot is the electric fence, and those 5kV gloves come in really handy for that.

 

[Texasmark1]

I do and make sure I know that if power is off it will stay off till finished.

When I worked at the Superconducting Super Collider we had locks with our names on them so that we could lock out circuits till finished what we were doing. If numerous people were working down the same link each had their lock attached and all had to be removed prior to energizing. Great idea and surely saved lives.

 

[Butch(OH)]

I agree, I am one of the lucky ones. 40 years ago I was working maintenance in a quarry and got my hand into 480 3 phase while standing in ankle deep water. If not for an alert (and brave) coworker who ran up and tackled me and knocked me off the buss I would have died on the spot.
Since the topic originaly was about a dead lineman I do have a question that I hope can be answered without and off topic argument being started.
How can an improperly hooked up little home generator power up the entire grid when it would also be powering up every home and buisiness attached to it?? Seems to me that would mean instant breaker trip on the generator? What am I missing? Please do not think I am advocating improper switching.

 

[centash]

Yes, I don't trust my own electrical skills enough to take any chances. I will even throw the switch on the Pole when doing electrical work. Ben

 

[K Effective]

Due to the 24/7 nature of a power plant, we do not use actual locks, but rather a tagging system- plastic (or metal) tags with component number, name and position printed on them zip-tied into the lock-out of the circuit or valves. All controlled electronically with a multi-layer computer program to assign work/workers to the clearance. Works really well, but does not replace personal voltage checks before work and after every break.

 

[UAFitter]

I've seen a pile of good advice on this site, and taken advantage of lots of it, and am grateful for all of it. What you just posted is none of that. In fact, it's probably among the very, very worst advice I have ever seen, anywhere.

Deliberately shorting mains power to ground as a means of ensuring de-energization is right up there with driving into a telephone pole to verify your car is stopped. If you do this, you are putting yourself at risk of arc flash and electrocution every time you do it. Google "arc flash" or watch a YouTube video if you don't believe me.

Working safely around electricity is a matter of knowing what you are doing and following the right procedures every time. Your man at the hospital, if he exists and really was working on a rooftop, should have deenergized it at the unit disconnect, which by code has to be within 10' of the unit. If it was old enough to be grandfathered and not to have a unit disconnect within 10', he should have gotten the location of its disconnect from the facility's blueprints, which by law the hospital is required to have documented. Then, he should have used a meter to verify power before the disconnect, and no power after it, and then he should have checked at the connection block in the unit, both phase to phase and to ground. He should also have used his meter to verify that control power was de-energized, since it can sometimes be fed from a separate source and even low voltage can be unpleasant. If lightning really did fuse those contacts, which seems like patent BS to me (and I've worked on a bunch of lightning-struck rooftops), then the only thing that he would have accomplished by shorting primary power to ground with a screwdriver would have been to make himself a path to ground through his screwdriver, unprotected by the circuit breaker. Ten seconds of competent work with a meter would have saved him. Don't tell me about not trusting your meter, either. If you don't have a test instrument you trust, you should get one, and if you can't get one, you shouldn't be doing work on any circuit that might be live.

You want to work like that, go on ahead, I guess. Vigo County is still part of the land of the free. Do everyone else around you a favor and keep your bad ideas to yourself. The only lesson the "boy" should have learned is "don't do electrical work with George."

 

[K Effective]

Thanks, UAFitter, you said what I deleted, much clearer and nicer.

 

[Bret4207]

I used to work at a lumberyard that had a hydro driven generator on the old dam. It provided all the power the place needed plus a lot more that was sold back to the local power supplier. I understood the plant was once a small towns only source of power. At any rate, many times I watched the chief millwright/welder/cabinetmaker/cranky-old-guy-who'd-been-there-forever stick a screw driver into the works to "adjust" something. IIRC this thing out out 600V right off the generator and God knows how many amps. Why that guy never fried is beyond me. Never turned the juice off to anything as far as I know.

 

[showcrop]

I am with UAFitter as well. I have heard intentionally shorting like that called "banging the breaker". We were trained in the fire service to never do it, and a lieutenant once got demoted for doing it. We had maybe four other legit means of verifying power off and protecting ourselves.

 

[rrc300 u]

UA fitter took the words out of my mouth. Arc flash and grounding tobsee if it's still on wtf Geo. A good meter is very cheap and if ya can't afford one don't do the work.

 

[Texasmark1]

Very good point. You're the first person of my knowledge that put that question to thought. Along those lines one of my long time questions/curiosities has to do with downed power lines after a storm where you have high power distribution lines lying all over the place and you are a power man, first responder type, or any first responder for that matter with power lines all over the place. Obviously if you see them sparking stay away but those that aren't and a situation where you accidentally come incontact with one....is it live or not? Surely the power guys are trained in how to access such an area.

 

[David G]

It aint dead if it aint grounded, "the lineman code".

 

[John T]

Neighbor George, as a retired and still alive electrical power distribution engineer IM SCARED OF ELECTRICITY AND RESPECT IT AND always double check and back up check any wires before I touch them.........

FYI This is a copy of what I posted below as its related.

GOTTA LOVE IT Electrical or Legal questions draw everyone out of the woodwork, many are experts (or think they are lol) and after 15 years here I've seen all sorts of POTENTIAL LIFE THREATENING ANSWERS AND OPINIONS. Its ones own life and home at risk which is why I as a retired electrical engineer always recommend people to consult a trained competent professional electrician and the NEC versus anything posted here INCLUDING MY COMMENTS as I'm long retired and rusty on the latest codes, but I still try my best to give safe sound advice even if some have far different methods or opinions or I disagree with Billy Bob and Bubba, you know the types, they wired their garage while downing a case of beer and by golly it works so they are experts who know more then the NEC and professional electricians..........

John T

 

[David G]

I want to add one thing.

You should NEVER short out anything 120 and higher without the correct arc flash precautions taken.

 

[Andy Martin]

(quoted from post at 05:43:54 01/02/17) Steve,
Lets say 440 will make you vibrate at 60 hertz for hours and it hurts.

Now for an electricians joke. Man tells his wife when she turns 40 he is going to trade her in for two twenty year old girls. Wife just laughs, tells her husband, You aren't wired for 220.

Be safe, short your wire before grabbing a handful.
If I were in a coffee shot, I could see where this conversation would be heading. Better not go there.

In reality, when you turn in a 40 year old, you get a 30 and a 10, not 2 20's.

 

[coshoo]

I don't short to ground, but I do a "triple test" with my meter each time. Use the meter on the circuit I just turned off to verify its not energized. Then check a different circuit that is on, to verify meter is working. Then check the circuit in question one more time, just to be on the safe side.

I've lived in several houses, and have yet to find one with really well marked circuit labels in the panel. One trick that I'm sure a lot know about is to plug in a radio to the outlet you are going to work on, and turn it up loud, so you can hear it while standing at the panel. Then flip the possible breakers, until the radio quits, then you know its off. Just make sure its not a radio with battery backup!

 

[bill b va]

George have you ever used the smoke test to find a short? just hold the breaker in or if its a trip or fuze jump with heavy conductor . works every time .

 

[js305]

I am a volunteer fireman just east of Lubbock Texas. Once a year one of the local power generating plants has a tour of the plant for the first responders in the district where they are located. They take us through the plant, in groups of about ten or less (easier to keep a watchful eye that way). Years ago they let us take cameras, but now, due to "homeland security" rules, we are allowed to take nothing that will take pictures. We can take our phones if they are turned off.

We were being shown a big row of what looked to me like large disconnects, each with a door on it about 2 feet wide and a big handle on the front. The one doing the talk put on two pairs of gloves, apron and face shield all the while talking about safety and precautions. On the floor there was a line painted in red that was labeled in a way that anyone crossing it without protective gear would be dismissed. OK, here we are, standing around this guy with all this protection on, and we are protected with only our earplugs and a few had redneck ball caps to protect their bald heads. I had the nerve to ask him about all of us, he kinda grinned, and let us know that bank of disconnects had all been de-energized for the tour, and went on to show us the procedure in doing so, so that he knew we were all safe in that location.

He also said, that in his 30 years of giving these tours, I was the first to ask that question...

I have seen arc flash up close and personal. We are taught how to remove a meter from a meter base at a fire scene. I had one arc all the way to the ground one night, about 5 feet of lightning that went all over the place. I had my bunker gear on with a face shield. We had reason to believe the place on fire was still "live". I took the handle of a fire axe, stood off to the side and knocked it down and away after breaking the seal. Never "assume" anything, as others have said as well.

 

[old-9]

This happened back in the 1960's in a major steel mill. An apprentice let his screwdriver slipp and shorted two phases of 480 volts. He was burned badly but healed. His glasses saved his sight, they were melted. Now the punch line, the peak power from the short showed up on the graph at the 138,000 volt substation! Now that is a big peak to show up that far up the line.
here

 

[Greg K]

Lol. You mean closing my eyes and turning my head? Just kidding. My old boss got a nice sunburn once from pushing a steel fishtail into a 440v panel.

 

[Steve@Advance]

And this one came up next...

Got him out of the gene pool!
Arc Flash Compalation

 

[37chief]

Glad you are ok. In my factory job, I would do the same thing with a screw driver. Even if I turned the power off, I grounded one leg of 440 to be sure. I took someone else's word the power was off one time. It wasn't I lost a good screw driver. this was before lockout devices were used on electrical disconnects. I have been told 110 v can kill just as easy. Stan

 

[dr sportster]

Although I have a set of shorts and grounds for high voltage cable I will say intentionally tripping a breaker is bad practice and can ruin the breaker. It is bad for 277 volt breaker as metal flies. But when I know a 277 volt lighting circuit is dead I will always drag it across the drop ceiling grid to ensure that blows and not my hand.

 

[Geo-TH,In]

David,
I came up with the same code 45 years ago when I was working at a Steel mill repairing furnaces and Chillers. If meter, you are dead. I have blown many tips off screwdrivers. I'll never bet my life on meters. The older I get, the more senior moments I have and all it takes you thinking your meter is set to measure ACV when your meter is on DCV or Ohms.

geo.

 

[markct]

Doesn't really take much of a sudden load to show up on the charts, just starting our barko log loader was enough they asked us to put a soft start on it

 

[moresmoke]

I was working with an electrician once. It didn't bother him to be poking his fingers around in a hot 500A 220V panel, but he was scared to death of the nearby electric fence??

 

[504]

There were two teenage girls killed a few years ago after lightning hit a center pivot. The disconnect was welded together,the handle said off but the buss was still powered. They were there to de-tassle corn. In IA.

 

[jeffcat]

Maximum Smoke test. Lets all of the smoke out of the wires and that stuck breaker. There used to be a max smoke penny device too used in the old fuse boxes! Down at work up in the third floor power room there is a big honker of a three phase box that supplies all of the power for the survalience systems. You should have seen how much smoke is locked up in a 400 amp system.

 

[Steve@Advance]

Just remembered another scary moment...

Bought a used 200a Square D I Line breaker off Ebay, don't remember what it cost, but expensive!

It looked good, like new almost. I went to plug it into the switch gear and as soon as it connected I heard a sizzle and a slight puff of smoke came from somewhere inside the breaker.

It was decision time...

Do I keep on pushing and hope this doesn't get real bad real quick?

Or do I drop this expensive breaker, (that is sure to break when it hits the concrete), and try to outrun the explosion?

Well, I decided it was too late to run, so I just pushed it on in. Whatever it was stopped sizzling and smoking, the breaker is still in there and working. Never had that happen before or since, no idea what it was other than something conductive must have been rattling around inside it.

 

[Geo-TH,In]

Yes, I do the smoke test on lawn mowers and tractors, but not when it comes to 110v/220/440.

On a few occasions the fuse in lawn mower blows. I put in a new fuse and it blow. So I've rigged up an old ammeter out of car. Installed ends on both sides of meter, plug ends in fuse holder, ammeter pegs out and then I look for a hot spot.

Today, my brake controller on truck started flashing two codes, OL and S.H. I had to look up OL is overload and S.H. is short. I spent hours looking for a short in trailer wiring no luck. Then I used an ammeter to apply 12 volts to the wire that powers up electric brakes. Full 12v to 4 electric brakes 8 amps. The primus IQ controller is 9 years old. I wondering if it isn't time to buy another controller. I might try removing power to one axle at a time and see if there really is a short.
No smoke on that test.

geo.