Electric Arc Flash and Arc Blast 6.5

Want to learn more about this topic? This video clip is extracted from Mike Holt's Understanding Electrical Theory Library, click here www.mikeholt.c... Electrical Training Products to see the full program.
For almost 50 years Mike Holt Enterprises has been creating quality products that help electrical professionals master their craft. Our products help electricians understand the National Electrical Code requirements needed for safe electrical installations, learn the skills needed to confidently pass electrical exams, and gain the technical knowledge that will take their careers to the next level. We would be honored to help you with your studies. Visit www.MikeHolt.com for exam preparation tips and training, instructor and curriculum support, continuing education options and much more. Need additional help? Call us at 888.632.2633.

[@electvolt67]

Tom, you have just diagnosed what has been wrong with me. I'm 56 and have always and still do work mostly everything live. I used to test everything with my fingers until I couldn't feel it anymore. Then I started using a tester because I got tired of buying new linesman pliers all the time. I have never been afraid of heights. I've worked on high-rises in NYC and asphalt silos. I also loved amusement rides. About 40 years old I started to get sick on rollercoasters. Then even mellow rides like Harry Potter....lol. Then I started to experience vertigo on larger heights. I usually just tell myself to ignore it because I know what it is. Now you just made me realize what caused it. Thank you.

[@dustylane9319]

Been around this stuff for 40+ years and learning/reviewing never gets old... Thanks Mike and Team

[@jorgehuizarsr8519]

Hi 👋 from Southern California George from fountain valley cali here thanks for sharing with us. Thanks for sharing the bike ride too ✌️✌️

[@dnavarro0523]

Mike! My name is Daniel Navarro, my pops was an early student of yours who has been a master and contracting under his own business since I was born. I recently decided I wanted to become a master and contract as well, hopefully taking the reigns when I am ready. He could not be more excited. He also said if passing the exam is my goal, then follow precisely your instructions and I will not fail. I have almost been through all of your public content and hope to purchase your material on the 2020 edition as he says when I take my exams, having studied this edition will benefit me the most. Your method of teaching, dedication, and love for this trade is truly inspiring. I hope one day I too can have such an understanding that I may teach the generation after myself. Thank you, Daniel Navarro.

[@BradKarthauser]

In the 80s my wife and I were eating in a restaurant next to a power substation. We were less than 50 ft from the power transformer. There was a hum, lights dimmed, then got bight, then the transformer exploded. Luckily the blast energy went up and not out. Flash, flames and copious amounts of smoke.

[@jolyonwelsh9834]

There's a youtube video of a New York city subway driver trying to remove a piece of debris that was thrown on the track. As he was trying to remove it, it somehow got lodged between the 3rd rail and the others rail. He got blasted with sparks and hot gasses just as demonstrated in your videos. It has the sound as well.

[@glenmartin2437]

Thank you! I was forced to work on live equipment under threat of being fired and being forced, literally into a corner. I am a retired research chemist, not an electrician. This stuff goes on all the time to this day. I left. Thanks for your videos.

[@Kimandy6862]

A second degree burn means that the second of the three layers of your skin was damaged or affected. The three layers of skin are the epidermis, dermis and hypodermis.

[@oculophilia918]

For the love of God that was so frustrating to watch. All guessing about a simple fact.

[@michaeleverest3487]

Speaking of burning your lungs... heard a story of an electrician who was removing the cover to a panel in an electrical room, as he turned around with the cover in front of his chest an arc occurred from the panel to a corner of the cover - he was now in the middle of the two, the arc struck his shoulder. He was found unconscious. A few days later, as he was sitting in the hospital, he began coughing up blood and stuff, turned out it was one of his lungs. It had cooked instantly. He couldn't work after that.

[@richardcranium3579]

Remember that getting between a neutral will lock you up as well especially a broken neutral in a triplex service running to the customers meter can. Everyone looks at the big flash and bang but it’s usually the unseen quiet ones that will sneak up on you. I’ve been a lineman for 36 years and we work things hot all the time (120 to 13,800. From a ‘lightning bug to a lighting bolt’ as the saying goes). In order for us to work something as dead (without gloves primary voltage wise) we have to be working between ground sets and have a visible air gap between source and line. Of course if the line were to become energized while it was being worked with ground sets installed then everything becomes energized at the same voltage until a protection device opens to clear it. Many linemen and apprentices see a set of grounds as absolute protection as long as they are working behind them but nothing could be further from the truth.

[@seantreakle1174]

Just because you turn the breaker off doesn't mean that it's off I've had a couple of times where I've had circuits that were double fed always use your hot stick.

[@Sparky-ww5re]

Good point. And here's something else to consider. When I was a teen on the family farm, I was changing a burned out element on an 80 gallon water heater in a barn. Uncle Gary said the breaker was off. Rightfully I check with my wiggy, first on a live circuit, then I test across the line side of the upper thermostat, circuit was dead. As I'm removing the wires on the element I get shocked and freeze up. If it wasn't for my uncle hearing me moan and knock me away with a 2x4 I might not be here to share my story. Turns out the water heater was served by 2 single pole 30 amp breakers and one of them was not turned off. circuits have been added and moved around over the years and so the panelboard label was outdated. You had to turn off all the 30 amp breakers to create an electrically safe work condition for the water heater. If I remember correctly the water heater was the only 30 amp circuit in that panel. That's how I learned to test for voltage from line to line and line to ground. When replacing a receptacle for example it's a good practice to test from hot to neutral, hot to ground, and neutral to ground, in case the receptacle was installed improperly.

[@citygirljace]

The note underneath the definition of electrically safe work condition clearly says it’s not a procedure, but rather a state.

[@joemomma7]

I'm working on something hot as I listen to this with ear buds. Last year got hit with 277 6 times back to back. Mostly my sweat sweat beads falling on a hot relay. I'll be feeling it later in life.

[@MikeHoltNEC]

Hum... six times back to back...

[@joemomma7]

@@MikeHoltNEC yes sir. Georgia Tech parking deck. Had to work late hours because that's where football players parked. Couldn't get to the panel. First time MC was basically wrapped around me. Got hit, moved it. Thought I was good, got hit an additional 5 times after. Guy under ceiling grid watching would go "ooof, you okay?" Reg and emergency power in relay ofcourse ep wasn't hot. I wasn't as knowledgeable as I am now but thought if I hook the hot up I shouldn't get hit but all I did was make more wires hot. It hurts will a more solid 'jolt' but 240v almost killed me in comparison to the numerous 277v hits. But I was also in the basement on a damp ground leaning over to furnace. But yes back to back. You're awesome BTW

[@larrylawson5172]

You do such a great job. I have some issues with your medical descriptions. You have always had appropriate people with great institutional knowledge. You have the Code Geek (you know who that is). The Engineer. The seriously experienced journeyman. The Apprentice. So that ALL aspects of the subject are covered so very accurately and thoroughly. When you talk about the effects of electricity on the body and the differences in levels of burns, you should have a professional on your panel. Either an Emergency Doctor or a Doctor that studies the effects of electrical burns or a Doctor that does long term care of electrical burns. Even 1st degree burns (redness and maybe swelling) cause damage. They can be so severe that a person could not work for a period of time because of the tenderness of the skin. Look at a northerner who has come to Florida for the sun in the middle of winter with a sunburned back and legs that cannot sit in a car to drive home to Minnesota or Illinois. A second degree burn will cause blisters but eventually sloughing of the affected area will happen. It might be so minor as breaking a small blister or as great as all of the surface skin of the arm or leg. If the man's arm in the ER is that deep purple there might be necrosis of the skin and muscles. It doesn't look charred but might still be a 3rd degree burn. This is such an important subject. The discussion of sequelae (pl) or sequela (sg) is so important. My father-in-law talked about an electrician that came to the farm to work on the silage unloader (200~ volts 1 ph) probably in the 1950's or 60's. He was standing in silage. Wet silage. He is wearing rubber boots. He is holding one wire in his left hand and pinching other wires with his right. "120," "120," "240," "ground," "120." Thanks

[@johnnyrayellison2724]

Especially since electrical injuries are the second leading cause of industrial fatalities, second only to falls!

[@winner1338]

3:00 Me, as a young project engineer, i find it hard to deal with contractors with macho attitudes. In the workpermit i stated "NO working on hot wires". But behind my back they still do it. I started to hate this role, to be responsible for what the contractors do.

[@nandingpanelo]

Thanks. Your a good man. Happy new year

[@charletonzimmerman4205]

Been shocked Numerous times over my 50 years, It always, HURTS, mostly cause of my, "TOUGH GUY" attitude, especially in the Navy. Were the "TAG OUT""/ LOCK OUT, started.

[@garbo8962]

We had a new remote site that had GE junk 13.2 KV dual outdoor service switchgear. that was designed to kill. Not only had a super high cal of 124 but had vents installed between 5 to 6' off the ground. In the event of a serious arc blast they would only need a small wisk broom to recover your ashes. I told them that they must install a remote operator at least 25' from the vents. As with other outdoor GE inferior switchgear they had to install several heaters inside switchgear to reduce humidity that was causing problems. We always had to wear long sleeve shirts & pants rated for 11CAL along with electrical rated work boots ( no metal eyelets ) that had non metallic toe protection. Luckily our 40 & 50 CAL hoods had battery operated cooling fans. Took me 40 years to have been told during a safety training c!ass to always take a deep breath & ho!d it whenever operating switchgear & safety switches. This would prevent you from inhaling what could be over 10,000 degree air into your lungs in an arc blast. Was taught as an apprentice to always stand on the side of a safety switch and to use your left arm whenever possible to turn a safety switch on or off.

[@jefffielder2429]

Thank you so much for sharing it's very helpful

[@steven7650]

Think of it this way. That copper plasma is the same concept behind an explosively formed penetrator where a copper disc is inverted into a hot stream of copper plasma to 'drill' through armor and then kill everything inside a vehicle. It's why the war in Afghanistan was so deadly until we got up-armored vehicles in 2010. But hey I'm sure those jeans or carhart's will hold up right?

[@johnnyrayellison2724]

I'm an Occupational Medicine Physician, could you send me a link to this study that Tom cited? Sounds very interesting to think about the cumulative effects of repeated electric shocks.

[@bobsmith1101]

Do these guys work in suits and ties? 😄

[@rameshdathrampersad9216]

hey Mike, once again great vid. But i have a transformer question again. If i am leaving from an electrical panel that has 240/120/208 volts delta with the high leg and i want to feed that into the primary side of a transformer to get a star secondary of 208/120 volts. What kind of transformer do i need? Just sayin if its a delta feed into the primary do i need a delta to star transformer. Just want to know what transformer to use and if it goes according to a star or delta voltage, if thats what i need as my primary. Thanks again. Much appreciated.

[@jolyonwelsh9834]

Maddox transformer manufactures a 3 phase transformer with a 240 volt delta primary and with a 208Y/120 volt secondary in all the standard KVA sizes. I believe that this is the transformer you are looking for. You wire it the same way as you would if it had a 480 volt primary.

[@rublar75]

Give Electrical Safety Training on the 1st day of an apprenticeship. Don't wait 4-years until they become "qualified" THEN give them the training. Most of the craziest stories happened when they were leaving and "didn't know". Don't wait to see if they survive the first 4-years THEN give them training. Do it in the beginning. It's one of the most dangerous hazard known to man. Why wait? Y’all need the lady master for this topic. She is well versed on the 70e topic. She’s good. Great information though.

[@MrJujubean]

What you guys say sounds good but thats not the way it works out in the field. I know electricians on youtube that kill the power to a service by going up on a fiberglass ladder to service coming in to the house and chut the lines hot, they say since they are not a path for current to go through because ladder is not conductor electrons have no place to go, they handle these wires with their bare hands.

[@MikeHoltNEC]

I don't understand what you are saying?

[@freiky26597]

could somedy tell me in New york city , i cant put no more than 9 line 12THHN inside pipe EMT 1". is that spitud or hve any cientific razon?

[@buckaroundandfindout]

How much do you want to bet that guy who keeps telling you you need your safety equipment works for a company that pays him to say that.?