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 Post subject: NFPA 70E Hazard Catagory 0 Ear Plugs
PostPosted: Sun Feb 12, 2012 4:56 pm 

Joined: Thu Aug 20, 2009 4:02 pm
Posts: 11
[INDENT=1]I just got to ask this question. I was reading the NFPA 70E 2012 and 2009 edition and apparently they require 'ear inserts, (ear plugs) when you are operating a breaker with the covers on. This includes a 120/208 volt 20 amp branch circuit breaker![/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Don't get me wrong, I'm all for safety and I'm the first to say something when something is not right and there are some good practices in the NFPA 70e that I use. However I do believe the ear plug requirement is overboard for the resetting of 20 or 15 amp breakers with the covers on.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Now everyone has to admit that most of the time when they turn on or reset a 20 or 15 amp branch circuit breaker without taking any of the covers off they are not wearing ear plugs.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Maybe I'm reading the NFPA 70E wrong, at least I hope so about this issue. This issue came up when a friend of mine told me about his boss (who is not an electrician and has no electrical experience and trying to read the NFPA 70e)wanting them to wear the ear plugs during a task like this. The Probelm was it created more problems then helped, because now one of the older workers/journeyman was having trouble hearing his foreman call for him LOL funnyImage![/INDENT]
[INDENT=1]Of course all the other workers are iritated by this too.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]What is your take on this?[/INDENT]


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PostPosted: Mon Feb 13, 2012 10:12 am 
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This is the standard requirement. It is probably overkill unless the fault current is pretty high. The blast pressure is a function of the fault current. There is unfortunately no good data on blast pressure and sound waves. There are about three IEEE papers and you can digest them and make your policy match the hazard if you feel NFPA 70E is overkill. Wearing hearing protection is pretty common in many industrial facilities so this isn't a burden but when you normal don't wear it, it's not a bad idea to question. The Tables are take or leave them. If you do calculations, you must decide when to use the right PPE for the hazard in your assessment.

The best paper on Blast Pressure is by Dr. Tom Neal and Dr. Roger Parry in IEEE

Roger Parry and Tom Neal, Specialized PPE Testing for Electric Arc Hazards Beyond Heat Exposure, Paper No. I&CPS-2004. [6] R. Lee, “Pressures Developed by Arcs”, IEEE Transactions on Industry Applications, Vol. IA-23, No.4 July/August 1987, pp. 760-764.

Other information on hearing protection is summarized in my paper.
Elihu "Hugh" Hoagland, "ARC FLASH PPE RESEARCH UPDATE", IEEE Paper [SIZE=3][font=Times New Roman]ESW2012-27from this month's Electric Safety Workshop.[/font][/size]


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PostPosted: Mon Feb 13, 2012 12:11 pm 
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Location: Calgary, Alberta, Canada
brother wrote:
[INDENT=1]I just got to ask this question. I was reading the NFPA 70E 2012 and 2009 edition and apparently they require 'ear inserts, (ear plugs) when you are operating a breaker with the covers on. This includes a 120/208 volt 20 amp branch circuit breaker![/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Don't get me wrong, I'm all for safety and I'm the first to say something when something is not right and there are some good practices in the NFPA 70e that I use. However I do believe the ear plug requirement is overboard for the resetting of 20 or 15 amp breakers with the covers on.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Now everyone has to admit that most of the time when they turn on or reset a 20 or 15 amp branch circuit breaker without taking any of the covers off they are not wearing ear plugs.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Maybe I'm reading the NFPA 70E wrong, at least I hope so about this issue. This issue came up when a friend of mine told me about his boss (who is not an electrician and has no electrical experience and trying to read the NFPA 70e)wanting them to wear the ear plugs during a task like this. The Probelm was it created more problems then helped, because now one of the older workers/journeyman was having trouble hearing his foreman call for him LOL funnyImage![/INDENT]
[INDENT=1]Of course all the other workers are iritated by this too.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]What is your take on this?[/INDENT]

We have to use some common sense when we review 70E or Z462 and ultimately define policy in an Electrical Safety Program. Normally energized electrical equipment is safe, approved, installed to NEC or CEC etc. Low voltage equipment is simple in design. For low voltage isolation under Normal conditions with doors closed or covers on we do not need any arc flash or shock PPE, no canal insert ear plugs required.

For 120/240V single phase the arc flash hazard is an arcing fault that can weld screwdrivers (ask any electrician) when workers are using uninsulated tools and doing repair and alteration work (which isn't allowed).

For normal isolation, follow a procedure and stand to the side and you don't need any arc flash and shock PPE for low voltage Standard lighting panel circuits etc.

Regards;
Terry


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PostPosted: Mon Feb 13, 2012 12:40 pm 

Joined: Tue May 24, 2011 5:52 am
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In my opinion, the boundary provisions of the panel at this point shouldn't always be imposed upon the set of electrical gear if its still in an enclosed application. If that weren't the case, all of us walking around a plant floor would have to be wearing long-sleeve cotton shirts, ear protection, eye-protection, etc. Its just to much to expect to impose a large scale arc-flash PPE requirement for everything, without reviewing the application first. I think its safe to say that the supervisor is being overly cautious when it comes to something he doesn't quite understand (then again, do any of us know for sure).

But it should be noted that even with low voltage applications, in the most unlikely event something happens faults heavilly, we can't just say that the panel can sustain every arc-blast, especially if its dated.

I think you can work the the supervisor to reevaluate the process, so that imposing a safe process is still evident at your location, but without the major red tape and over the top structure.

Brother, I would like to know a few things if you have an opportunity: As elihuiv mentions what was the fault capacity at the main, did your electrician check to see what caused the trip first before resetting the breaker? how old is the panel?


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PostPosted: Mon Feb 13, 2012 2:13 pm 

Joined: Sun Dec 12, 2010 5:00 pm
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Location: Idaho
brother wrote:
[INDENT=1]I just got to ask this question. I was reading the NFPA 70E 2012 and 2009 edition and apparently they require 'ear inserts, (ear plugs) when you are operating a breaker with the covers on. This includes a 120/208 volt 20 amp branch circuit breaker![/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Don't get me wrong, I'm all for safety and I'm the first to say something when something is not right and there are some good practices in the NFPA 70e that I use. However I do believe the ear plug requirement is overboard for the resetting of 20 or 15 amp breakers with the covers on.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Now everyone has to admit that most of the time when they turn on or reset a 20 or 15 amp branch circuit breaker without taking any of the covers off they are not wearing ear plugs.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]Maybe I'm reading the NFPA 70E wrong, at least I hope so about this issue. This issue came up when a friend of mine told me about his boss (who is not an electrician and has no electrical experience and trying to read the NFPA 70e)wanting them to wear the ear plugs during a task like this. The Probelm was it created more problems then helped, because now one of the older workers/journeyman was having trouble hearing his foreman call for him LOL funnyImage![/INDENT]
[INDENT=1]Of course all the other workers are iritated by this too.[/INDENT]
[INDENT=1] [/INDENT]
[INDENT=1]What is your take on this?[/INDENT]


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PostPosted: Mon Feb 13, 2012 2:15 pm 

Joined: Sun Dec 12, 2010 5:00 pm
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Location: Idaho
Well I guess you are now getting to the same frustration level as the rest in industry when dealing with the NFPA70E. My take is we are all over exaggerating the rules because of the OSHA use of NFPA70E in their investigations. We all know it would take a very large (room size) transformer to cause an arc blast large enough to shatter your eardrums on a 120/240V lighting panel. We had an assessment done at our plant so we did not have to follow the tables in the book and instead use our Arc Flash labels as the guidelines to the proper PPE. Our electricians wear the proper PPE on a daily basis and being we are an industrial facility, wear ear plugs all day long, so that is not an inconvenience for us. Arc Flash and Blast are real. They happen every day and are very tragic for those involved. Your common sense tells you it is overkill, but if someone were to have a high impedence transformer with lots of available current on a 120V/240V system, then they should be wearing ear plugs. If it were to blow, the eardrums will rupture. Also it was not mentioned, but you also need long sleeve shirt and pants, safety glasses or goggles and leather gloves (7mm for 2012) to operated this breaker (CAT 0) also.....Yes it is getting frustrating. How about clothing all 400 workers as we have in our plant to operated a switch or disconnect when locking out!!


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PostPosted: Mon Feb 13, 2012 7:04 pm 

Joined: Thu Aug 20, 2009 4:02 pm
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msimms wrote:
In my opinion, the boundary provisions of the panel at this point shouldn't always be imposed upon the set of electrical gear if its still in an enclosed application. If that weren't the case, all of us walking around a plant floor would have to be wearing long-sleeve cotton shirts, ear protection, eye-protection, etc. Its just to much to expect to impose a large scale arc-flash PPE requirement for everything, without reviewing the application first. I think its safe to say that the supervisor is being overly cautious when it comes to something he doesn't quite understand (then again, do any of us know for sure).

But it should be noted that even with low voltage applications, in the most unlikely event something happens faults heavilly, we can't just say that the panel can sustain every arc-blast, especially if its dated.

I think you can work the the supervisor to reevaluate the process, so that imposing a safe process is still evident at your location, but without the major red tape and over the top structure.

Brother, I would like to know a few things if you have an opportunity: As elihuiv mentions what was the fault capacity at the main, did your electrician check to see what caused the trip first before resetting the breaker? how old is the panel?

Im not sure what the fault current was at the main. And yes the electrician did check to see what caused the trip. Basically it was a coffee pot, toaster, microwave, and a baker oven on 1 circuit. So the 20 amp single pole breaker tripped. This was at a hospital, and it was in their break room, so noise is not an issue here. The ear plug requirement is just getting over board a bit, not to mention that most people are not going to follow that rule just for a 20 or 15 amp single pole breaker that needs resetting in a 120/208 panel with the covers on, not to mention they will not be wearing leather gloves either. I think they should change the ear plug requirement to "AN" like the leather gloves, AN means As needed or just make it optional. :)


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PostPosted: Sun Feb 19, 2012 5:48 pm 

Joined: Sat Dec 26, 2009 10:49 am
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The problem is the end user, the electrician or machine operator is not always in charge of maintenance, or has a history of the past problems with the equipment, in this case a brance circiut breaker. To say that no hazard exizts is like saying a box of dynimate is not a hazard. We all know that smoking around explosives is not a good idea, and operating or changing the state or contion of electrical disconneting devices, switches, breakers has and can cause failures. Hearing protection is small change in the schiem of things, why the big deal. Put your ear protective devices in and hear the birds or you child in the class play. The reference in 70E to "AN" allows us to analyis shock or burn hazards, but not to dismiss them as no big deal. Every day I have customers ask me why the big change in work practices, and I always tell them that 70E is a MINUMI standard and we can always do more to protect ourselves. The tables in 70E have very difinate limitations, and we must always do some type of hazard analysis. Do you feel safe in an elevator that was made in 1910, just because it passed inspection at the time of installation? Electrical equipment has no specific requirment for re-inspection, at least elevators do. Realize we used to teach electricians to measure voltage with their fingers, you still think that's a good idea?


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PostPosted: Tue Feb 21, 2012 5:02 am 
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Very interesting thread. Here's my take... previous versions (pre-2012) of NFPA 70E had an exception that excluded systems 240V fed by a single transformer <125kVA. The 2012 70E passed that determination on to the IEEE 1584 which still has the exception. If the panel is <240V and fed by a single transformer <125kVA then... there is no arc flash hazard. So, what PPE is required for NO HAZARD? Why the big deal? This is a hospital break room and, from my experience, I would almost guarantee the panel will meet the exclusion. So, if I'm working on this panel, I'm going to take a look at the upstream transformer, do an analysis... <240V, <125kVA etc and protect accordingly. Once the analysis is done, the Tables no longer have precedence.


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PostPosted: Thu Feb 23, 2012 7:17 am 
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It does not say there is no hazard; it says equipment below 240V need not be considered unless it involves at least one 125kVA or larger low impeadance transformer in its immediate power supply. This means you do not have to calculated the incident energy at this location; not that no PPE is required.

Under normal operating conditions, enclosed electrical equipment that has been properly installed and maintained is not likely to pose an arc flash hazard. I believe simple operator lockout for this equipment would not require PPE; however, for tasks such as resetting a breaker after a fault condition or for anything requiring removal of covers HRC 0 PPE should be worn.


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PostPosted: Mon Mar 05, 2012 11:48 am 

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[font=Tahoma][color=#141414]IMPORTANT: Please read the following answer I got from a Canadian Standard Association member (project manager) of the Z462 committee regarding the Ear plugs:[/color][/font]
[font=Calibri][color=#002060]As discussed, I again put this question before the hearing protection specialists on our Z462 Committee as well as our Z94.2 Hearing Protection Committee. Following is a summary of their response:[/color][/font]
[font=Calibri][color=#002060]Percussive noise above 120 dB can cause permanent hearing loss. Therefore, anytime there is potential exposure to percussive noise above 100 dB, hearing protection should be worn.[/color][/font]
[font=Calibri][color=#002060]The sound level of and arc flash event is proportional to the [b]fault current[/b], but not to the arc duration, i.e. the greater the arc current, the greater the explosion on the first half cycle of the arc. Consequently, the sound level does not necessarily track the incident energy level which is proportional to fault current and arc duration. For instance, an arc flash with a fault current of 10kA that lasts for less than a cycle due to a current limiting fuse, could have a high sound level, but a fairly low incident energy. So we could have HRC0 tasks with high enough sound levels to create permanent hearing loss (ie, producing percussive noise above 120 dB). So, the critical factor in determining whether or not hearing protection should be used when working on energized or potentially energized equipment is the fault current associated with the equipment. [/color][/font]
[font=Calibri][color=#002060]Based on studies of electrical arc events, it was found that a fault current of as little as [/color][/font][font=Calibri][color=#002060][b]6 kA[/color][/font][/b][font=Calibri][color=#002060] would produce an arc with a peak noise level above 120 dB at 0.5 m from the event. From this study, it was recommended that hearing protection be worn by anyone exposed to such an event.[/color][/font]
[font=Calibri][color=#002060]From this understanding of the percussive noise hazard, if the maximum fault current is not known, hearing protection should be worn by those working on energized or potentially energized equipment. If it can be determined that the maximum fault current does not exceed [/color][/font][font=Calibri][color=#002060][b]6 kA[/color][/font][/b][font=Calibri][color=#002060], then the potential for hazardous percussive noise from an arc flash is very slight [/color][/font][font=Calibri][color=#002060][b]and there would be no need for hearing protection.[/color][/font][/b]


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PostPosted: Fri Mar 09, 2012 10:00 am 
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Good information Paul. 6kA is well within what could be considered normal fault current on a residential panel. As unlikely as it seems, the CSA seems to have determined there is potential for permanent hearing damage at those current levels and one can presume on similar basis the NFPA 70E authors choose to include the requirement for hearing protection.

As an observation I will add that it is sometimes a challenge to teach this material when workers sense the code authors have abandoned the workers in a position to always be wrong. We've tried to create a non-challenged culture with repeat instruction at a few industrial facilities, but asking a commercial electrician to put on hearing protection to operate a fully enclosed circuit breaker might be taken as a set up. To ask a nontechnical facilities manager to put on hearing protection to operate circuit breakers would imply equipment failure. Not sure the code writers consider these aspects.


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PostPosted: Fri Apr 18, 2014 8:00 am 
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Here is a new article on arc flash and ear canal inserts.

http://electricalarcflashsafety.com/2014/04/ear-canal-inserts-plugs-for-arc-flash-in-nfpa-70e-research/


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