It is currently Tue Sep 26, 2017 12:45 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: Cause of rise in frequency of arc flash incidents
PostPosted: Wed Apr 04, 2012 5:49 am 
Offline

Joined: Tue Apr 03, 2012 5:00 pm
Posts: 7
[SIZE=3][font=Times New Roman]Hello everyone, I just signed up, i'm researching the causes of the rise in frequency of arc flash incidents.[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]To anyone who can shed some light on the subject, in your personal opinion, can you reduce the reasons for the increasing frequency of arc flash incidents and accidents to one or two main reasons?[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]What would those reasons be, please?[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]Are there any other associations or trends that you have noticed, possibly things which are not yet fully accepted or that the electrical working public has not yet been made aware of?[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]The reason I am asking is for developing 'counter-arguments' for a term paper- opposition to accepted and published theories as a discussion point or a brainstorming point. As safety requirements and training increase. many areas of industrial accidents are decreasing in number, but arc flash incidents do not seem to follow this trend. I've read a number of papers, industry journals/articles on the subject, spoken to numerous NRTL safety inspectors and AHJs, but have not found any real consensus.[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]Any ideas?[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]Personally, I am wondering if more compact designs of recent manufacture have shortened clearances (and creepages) from what they used to be, thereby reducing previously unrecognized safety aspect (distance) as this is a significant factor in maintaining an arc flash or plasma current.[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]A second possibility is probably increased demand for 'up-time', causing shortcuts in troubleshooting or maint/repair safety procedures, but this seems like kind a broad sweep for use as a reason... are there any more accurate portions of this broad spectrum that you think are more causal than other reasons?[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]Thanks to anyone who can shed some light on the subject- either personal opinion or a more formal study or research: any comments are welcome.[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]FYI- I am familiar with most arc flash calculations, although i am not as good at calculating fault current availability- but that is probably mostly due to the fact i have not worked enough with the electrical utilities.[/font][/size]
[SIZE=3][font=Times New Roman][/font][/size]
[SIZE=3][font=Times New Roman]Thanks again, these kinds of forums are really excellent mixes of professionalism and open discussion, great for brainstorming and looking into undisclosed reasons and causes for incidents.[/font][/size]


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Apr 04, 2012 6:14 am 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
Good topic. Just throwing a couple ideas out there:

-More efficient power systems, lower Z leads to higher fault currents
-Lack of preventative maintenence, this, along with training, seems to be the first things companies cut back on when trimming a budget
-Combining of trades - I see more and more companies cutting back staff and having people without the background, training, and experience needed to do electrical work. The jack of all trades, master of nothing maintenence man is dangerous IMHO.
-The internet, perhaps there are not more incidents, perhaps we just hear about them more often
-Old equipment - this ties in with PM's but if you have a 30 year old breaker and it has never been overhauled as recommended by the OEM you are just asking for a failure. In the nuclear world they are required to overhaul breakers every 10 years. In the non-nuclear world that rarely happens, at best basic PM's are performed every few years and some tech squirts spray lubricants (Technition in a can) into the operating mech which works great for a few days but is one of the most common causes of breaker failure.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Apr 04, 2012 8:49 pm 
Offline
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 1762
Location: North Carolina
EFSI recently published data on electrical injuries. I have no idea what you are talking about because according to their data, electrical injuries in general (all kinds) have significantly decreased over the past 10-15 years. Probably the only major difference is there is greater understanding and thus recognition.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Apr 05, 2012 7:59 am 
Offline
Sparks Level
User avatar

Joined: Mon Jul 09, 2007 11:43 pm
Posts: 51
Location: Sheffield, England
Hi John, I'd like to know a little more about your source of information to say that flash incidents have increased. I agree with Paul that the ESFI stats have shown a significant decrease in electrical injuries over the last 15 years but my reading is that over an 8 year period non fatal injuries and burn frequencies in private industry have flattenned out. You mention incidents and not injuries so I'm very interested, good stats in this this area seem to be very difficult to get hold of.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Apr 10, 2012 10:18 am 
Offline

Joined: Tue Apr 03, 2012 5:00 pm
Posts: 7
Mike Frain wrote:
Hi John, I'd like to know a little more about your source of information to say that flash incidents have increased. I agree with Paul that the ESFI stats have shown a significant decrease in electrical injuries over the last 15 years but my reading is that over an 8 year period non fatal injuries and burn frequencies in private industry have flattenned out. You mention incidents and not injuries so I'm very interested, good stats in this this area seem to be very difficult to get hold of.


I have to admit i cannot recall where i first heard that arc flash incidents were increasing- I'll have to go through my notes and downloads- I may very well have misread or misinterpreted something.
In Reducing non-contact electric arc injuries [Kowalski-Trakofler, Barret], "...the population of workers who may be affected by electric arc flashes couldbe on the rise..." certainly does not suggest what i was claiming...
The paper goes on to say '...it may be inferred... could be on the rise...'. Again, no actual data.

I'll check to see where i could have heard this, it is possible too that it was heard in passing from an instructor in industrial engineering...

If I have misspoken, I sincerely apologize.

But none-the-less thanks for your inputs- good leads to follow to find more and more accurate info.

john


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Apr 10, 2012 10:20 am 
Offline

Joined: Tue Apr 03, 2012 5:00 pm
Posts: 7
PaulEngr wrote:
EFSI recently published data on electrical injuries. I have no idea what you are talking about because according to their data, electrical injuries in general (all kinds) have significantly decreased over the past 10-15 years. Probably the only major difference is there is greater understanding and thus recognition.

Thanks Paul, i may have misread or mis-remembered that claim... I'll look for where i found it, because now i too am interested to see where is came from if it is contrary to industry data.

Thanks for your patience,

John


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Apr 10, 2012 5:15 pm 
Offline
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 1762
Location: North Carolina
There is precedent for AWARENESS of arc flash injuries. Ralph Lee and others did the research and published the results in the 90's. Right around the turn of the century, IEEE and NFPA incorporated the results of those experiments. Awareness especially in the U.S. quickly ramped up when in 2002, NEC began requiring arc flash hazard labels and made reference to NFPA 70E. In 2004 the first truly workable version of 70E was published, and NEC (contrary to nay sayers) did not retract the labelling requirement in the 2005 edition. As far as I know the first fines were issued by OSHA for arcing fault hazards to an automotive company in 2006. This was pretty much the wakeup call to everyone in the electrical business.

I can definitely make the statement then that awareness has been on the rise tremendously in the past 10-15 years. Prior to that it is not that arc flash hazards didn't exist...it's just that without actual experimental data, usable models, and consensus safety standards to use, anyone concerned with it was "on their own" in terms of addressing it. Prior to that time period, the extent of the knowledge was to stand to one side and face away from the door when opening or closing a breaker.

Data from the ESFI reflects the renewed awareness and interest in addressing electrical safety:
http://www.esfi.org/index.cfm/page/Electrical-Safety-Then-and-Now/cdid/12394/pid/10272

Where we are at now is that there are still lots of questions of details about how to address the issue and refinements to the basic models. There are now plenty of available solutions to mitigate arc flash hazards. There are a very small number of solutions on the market that claim to totally eliminate it. But we are still a ways off from seeing arc flash hazard elimination (as opposed to mitigation) become main stream because there are not many standards or a lot of independent test data to verify the claims yet.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Sun Apr 15, 2012 3:17 pm 
Offline

Joined: Tue Apr 03, 2012 5:00 pm
Posts: 7
PaulEngr wrote:
There is precedent for AWARENESS of arc flash injuries. Ralph Lee and others did the
Data from the ESFI reflects the renewed awareness and interest in addressing electrical safety:
http://www.esfi.org/index.cfm/page/Electrical-Safety-Then-and-Now/cdid/12394/pid/10272

Where we are at now is that there are still lots of questions of details about how to address the issue and refinements to the basic models. There are now plenty of available solutions to mitigate arc flash hazards. There are a very small number of solutions on the market that claim to totally eliminate it. But we are still a ways off from seeing arc flash hazard elimination (as opposed to mitigation) become main stream because there are not many standards or a lot of independent test data to verify the claims yet.


Paul- thank you very much for the link-

i apologize for posting heresay- i have to complete this paper by thursday, i'll post a copy afterwards. i wish i had time for people to review it here, but since i plan on using the paper for things- I'll still welcome input.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Apr 16, 2012 6:40 pm 
Offline

Joined: Tue Apr 03, 2012 5:00 pm
Posts: 7
Zog wrote:
Good topic. Just throwing a couple ideas out there:

-More efficient power systems, lower Z leads to higher fault currents
-Lack of preventative maintenence, this, along with training, seems to be the first things companies cut back on when trimming a budget
-Combining of trades - I see more and more companies cutting back staff and having people without the background, training, and experience needed to do electrical work. The jack of all trades, master of nothing maintenence man is dangerous IMHO.
-The internet, perhaps there are not more incidents, perhaps we just hear about them more often
-Old equipment - this ties in with PM's but if you have a 30 year old breaker and it has never been overhauled as recommended by the OEM you are just asking for a failure. In the nuclear world they are required to overhaul breakers every 10 years. In the non-nuclear world that rarely happens, at best basic PM's are performed every few years and some tech squirts spray lubricants (Technition in a can) into the operating mech which works great for a few days but is one of the most common causes of breaker failure.


Hello Zog,
May i use your quotes directly in my paper? If so, what name should i attribute this to? Thanks!


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Apr 17, 2012 10:45 am 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
Forum posts are free game as far as I am concerned, but these are just my own theories/observations, nothing I have researched as contributing factors to frequency of arc flash accidents.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Apr 17, 2012 12:50 pm 
Offline
Sparks Level
User avatar

Joined: Sat Jun 07, 2008 5:11 pm
Posts: 143
Location: Connecticut
Like to add to Zog's list...

Unavailability of machine/plant down time to perform PM and testing. Especially in processes that run 24/7.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Apr 18, 2012 4:13 pm 
Offline
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 1762
Location: North Carolina
geh7752 wrote:
Like to add to Zog's list...

Unavailability of machine/plant down time to perform PM and testing. Especially in processes that run 24/7.


There is an OSHA letter of interpretation explaining what they (and NEC and 70E) intend by the term "continuous process". It is NOT how it is commonly interpreted. Wish that there were more folks reading this. OSHA is specifically referring to for instance if you had a panelboard that feeds a hazardous location ventilation system AND some non-critical system that requires maintenance. It is effectively an extension of the "greater hazard" rule. It is NOT as has been misinterpreted, a "get of jail free card" for continuous process industries to justify not shutting down due to production interruptions.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25559


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Apr 19, 2012 12:43 pm 
Offline
Sparks Level
User avatar

Joined: Sat Jun 07, 2008 5:11 pm
Posts: 143
Location: Connecticut
Waving an OSHA letter in management's face can be a tricky situation. You may win the battle but lose the war. In my experience companies are getting better complying with safety in general. Much of this is due to better educating management on the importance of a safe work environment. Insurance carriers such as FM Global are pushing electrical safety and PM programs as a means to reduce claims and give companies a break on the premiums. However, the problem starts because "continuous process" is based on interpretation. Give 5 people the same NEC code problem and you will get 5 different interpretation.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
© 2017 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883