# 4 injured, 2 sent to burn unit, 1 dead



## Zog (Apr 15, 2009)

Arc flash in a small medical center, LV stuff, the stuff some think they won't get hurt because "They know what they are doing" 

http://www.carolinalive.com/news/story.aspx?list=~\home\lists\search&id=691856

Bless these guys and their families but I bet he knew what he was doing too.


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## BBQ (Nov 16, 2010)

Not only did a man lose his life he spent the last month of his life in the worst shape possible.



> The Horry County Coroner's office confirms Archie "AB" Johnson died Wednesday night after sustaining severe burns in an October 28th electrical accident at Seacoast Medical Center in Little River.


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## B4T (Feb 10, 2009)

I understand the "message".. but I would still like to know what voltage the men were working with..

Upon my travels.. I have never seen arc flash on 120/208 or 120/240 panels.. I'm not say it doesn't happen.. just never came across it or met anyone who has..


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## dronai (Apr 11, 2011)

No details, wonder what happened.


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## cicirich (Apr 8, 2011)

It happened to me on 120/208v 3 phase panel. The loudest explosion I had ever heard in my life. Main never tripped and I could hear the electricity in air. Since then I always wear my PPE no matter how routine the job is. All I was doing was checking the voltage on the panel and as soon as I put one of my test leads on a breaker it almost instantly exploded.


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## TOOL_5150 (Aug 27, 2007)

cicirich said:


> It happened to me on 120/208v 3 phase panel. The loudest explosion I had ever heard in my life. Main never tripped and I could hear the electricity in air. Since then I always wear my PPE no matter how routine the job is. All I was doing was checking the voltage on the panel and as soon as I put one of my test leads on a breaker it almost instantly exploded.


Was your meter CAT rated?:blink:


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## varmit (Apr 19, 2009)

Arc flash is more dependent on available fault current than system voltage. There was a story in a recent EC&M magazine about a fatality working on a 230 volt system. Normally, 208 or 230 volt systems are smaller with less available fault current, but there are many places with high current, low voltage systems that could put a hurtin' on you if something goes wrong.


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## GEORGE D (Apr 2, 2009)

cicirich said:


> It happened to me on 120/208v 3 phase panel. The loudest explosion I had ever heard in my life. Main never tripped and I could hear the electricity in air. Since then I always wear my PPE no matter how routine the job is. All I was doing was checking the voltage on the panel and as soon as I put one of my test leads on a breaker it almost instantly exploded.


Damn, that sucks man. That's really scary


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## Zog (Apr 15, 2009)

varmit said:


> Arc flash is more dependent on available fault current than system voltage. There was a story in a recent EC&M magazine about a fatality working on a 230 volt system. Normally, 208 or 230 volt systems are smaller with less available fault current, but there are many places with high current, low voltage systems that could put a hurtin' on you if something goes wrong.


Fault current and clearing time are the key factors, and smaller, cheaper, less complex LV systems often have very long clearing times because they don't have a properly coordinated system and use cheap OCPD's that offer little or no selectivity.


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## jza (Oct 31, 2009)

cicirich said:


> It happened to me on 120/208v 3 phase panel. The loudest explosion I had ever heard in my life. Main never tripped and I could hear the electricity in air. Since then I always wear my PPE no matter how routine the job is. All I was doing was checking the voltage on the panel and as soon as I put one of my test leads on a breaker it almost instantly exploded.


What?


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## dronai (Apr 11, 2011)

cicirich said:


> It happened to me on 120/208v 3 phase panel. The loudest explosion I had ever heard in my life. Main never tripped and I could hear the electricity in air. Since then I always wear my PPE no matter how routine the job is. *All I was doing was checking the voltage on the panel and as soon as I put one of my test leads on a breaker it almost instantly exploded.*





:blink: How can this happen ?


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## backstay (Feb 3, 2011)

Anything is possible in cyber space.


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## Zog (Apr 15, 2009)

cicirich said:


> It happened to me on 120/208v 3 phase panel. The loudest explosion I had ever heard in my life. Main never tripped and I could hear the electricity in air. Since then I always wear my PPE no matter how routine the job is. All I was doing was checking the voltage on the panel and as soon as I put one of my test leads on a breaker it almost instantly exploded.


The breaker or your meter?


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## Specialist (Nov 18, 2011)

Cheap or Faulty meter maybe, or wrong setting. I was pricing a re-wire in a Carpet factory some years ago & witnessed the explosion when their maintenance Electrician was useing his meter to check the supply to a motor panel. After things calmed down we checked his meter & found 2 things: 1) It was a cheap meter & rated Cat1 and 2) Rushing to do the test he'd put his meter on AC current not voltage.
Apart from a severe burn to the hand holding the meter he lost his job for incompetence.


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## jmsmith (Sep 10, 2011)

As to a 120/240VAC single phase system, why would you wait to pull a meter with load off it? Or maybe prevent a wrench from getting across panel lugs ahead of your main breaker? A lot can go on before the primary fuse finally opens on a transformer, and those also have been known to fail.... Things can get awful ugly real quick!!! Be careful and think things through first...

Sent from my iPhone using ET Forum


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## cicirich (Apr 8, 2011)

TOOL_5150 said:


> Was your meter CAT rated?:blink:


Meter was a fluke T5-600


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## cicirich (Apr 8, 2011)

Zog said:


> The breaker or your meter?


The top portion of a the panel.


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## cicirich (Apr 8, 2011)

Specialist said:


> Cheap or Faulty meter maybe, or wrong setting. I was pricing a re-wire in a Carpet factory some years ago & witnessed the explosion when their maintenance Electrician was useing his meter to check the supply to a motor panel. After things calmed down we checked his meter & found 2 things: 1) It was a cheap meter & rated Cat1 and 2) Rushing to do the test he'd put his meter on AC current not voltage.
> Apart from a severe burn to the hand holding the meter he lost his job for incompetence.


Meter was a Fluke T5-600. And meter was set to read voltage plus I had just tested voltage on another breaker in that same panel a second before I checked the one that caused the arch flash. I had one lead on the neutral and the other lead on the breaker.


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## cicirich (Apr 8, 2011)

dronai said:


> [/B]
> 
> 
> :blink: How can this happen ?


Believe me I asked myself this same question 100 times over after it happened and played the scenario over and over in my head. Still not really sure what happened myself but the building's insurer sent out an electrical engineer and some kind of inspector to check the panel before any repairs were done to take pictures and to come up with theory. The building wanted to make sure they were covered but after they finished their inspection they told the building they had believe a K O blank had fallen into the panel and when I had touched the breaker with my test lead the K O blank and phases had bucked phases. Before all that they checked and tested my meter, confirmed that I wasn't drilling or landing wires into a hot panel, checked the dead front for burn marks to make sure it didn't slip out of my hands. I don't really believe the KO theory myself but I still don't know what really happened. 
All I can say is be careful when you go into a 30 plus year old highrise building. This building had pretty much 30 years of electrical contractors going into there panels adding sub panels, adding breakers moving circuits around. Looked like a complete rats nest with splices all over insided the panel. You never know what the last guy before you did and to me it seems nowadays nobody cares about craftsmanship anymore. First thing I always here nowadays is how cheap and how quick can you did it.


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## cicirich (Apr 8, 2011)

The panel I was testing voltage on had no main breaker with four sub-panels and recptacles circuits coming off of it. The one panel was being feed from another panel from the floor above with feed thru lugs. That also had four sub-panels coming off of it with no main breaker also. The rest of the circuits were also power for outlets. All 8 sub-panels was power for outlets and anything else needing 120v power. So then that first panel was being feed from a 400amp fuses three phase disconnect. When we went to test the fuses to see if they had blown from the arc flash we discovered they were still good. So then we opened up the transformer and saw all the coils melted because the fuses never blew and then checked the high voltage side feeding the transformer and saw that never tripped also.


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## Big John (May 23, 2010)

cicirich said:


> ...They told the building they had believe a K O blank had fallen into the panel....


 I had that happen working on a 480 service to a fire station. This was before I knew what PPE was, reaching into a trough above the panel and an old KO slug fell down through the nipple and into the panel.

Didn't flash over but listening to it rattle down through the guts was definitely the longest 2 seconds of my life.

-John


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## chicken steve (Mar 22, 2011)

BBQ said:


> Not only did a man lose his life he spent the last month of his life in the worst shape possible.


they can articulate as well as anyone else too, so it's_ very_ misleading

it's the whole fluid shift / electrolyte thing 

they're gonners, and they_ know_ it.....

~CS~


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## Mshea (Jan 17, 2011)

In theory voltages below 240 volts cannot sustain an arc. an arc fault requires the air to ionize and conduct. It may be a misnomer to call it an arc fault when there is no arc but only a blast, explosion or other fault like ejected molten copper. Now if you are the guy standing in the path of the blast you may not care about the difference. When an arc is sustained, faults can flash over to other phases and bonded or grounded metal. The duration of an arc is limited to upstream protection and for a utility supplied service that can take a very long time often longer than a few cycles. 
A simple illustration of this differnce is under 240 volts you ground your screw driver off of a conductor. The screw driver, enclosure and the conductor instantly give off hot metal and a very bright light as well as a huge bang but in the instant the ground is removed the fault current stops assuming we didn't weld it all together or create enough carbon to conduct through that medium.
Now do the same thing on a 480 volt conductor and the fault can involve the adjacent phase wire via the plasma created whereby the air itself conducts electricity. This arc may continue long after the screw driver was removed and if the OC devices don't operate the arc can sustain a long time. The hard contact may operate the OC device as bolted faults clear effectively but an arc can be sustained at a current level below the ratings of OC devices. A jacobs ladder is a controlled arc and it can last a very long time. Of course the more conductors that get involved in an arc fault the more likely the current will blow some OC protection.


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## chicken steve (Mar 22, 2011)

http://www.repairfaq.org/sam/jacobs.htm#jlwij

hadda look that up Mshea.......




> The hard contact may operate the OC device as bolted faults clear effectively but an arc can be sustained at a current level below the ratings of OC devices. A jacobs ladder is a controlled arc and it can last a very long time


 
now that's worth asking more about imho......




~CS~


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## Zog (Apr 15, 2009)

Big John said:


> I had that happen working on a 480 service to a fire station. This was before I knew what PPE was, reaching into a trough above the panel and an old KO slug fell down through the nipple and into the panel.
> 
> Didn't flash over but listening to it rattle down through the guts was definitely the longest 2 seconds of my life.
> 
> -John


Like Russian Pichinko?


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