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 Post subject: 2015 - 130.7(15) Informational Note 2
PostPosted: Thu May 03, 2018 7:35 am 
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We had a debate over this note this morning and my site search's didn't turn up much for additional input. In your opinion, what does this note mean? Thanks in advance.

Informational Note No. 2: The collective experience of
the NFPA 70E Technical Committee is that, in most cases,
closed doors do not provide enough protection to eliminate
the need for PPE in situations in which the state of the
equipment is known to readily change (e.g., doors open or
closed, rack in or rack out).


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Fri May 04, 2018 11:57 am 
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It's a formal way of saying if there is an arc flash, you don't know if the doors will stay closed. Even if they did, some of the energy finds every crack, hole etc. and can make it out anyway.

Changing the state of the equipment could be taken as the famous "interaction" that was introduced in the 2009 Edition of NFPA 70E.

To help resolve some of the confusion, NFPA 70E introduced the concept of "normal operation" which meeting the following criteria.

Equipment is properly installed
Equipment is properly maintained
Equipment is used in accordance with instructions etc.
Equipment doors are closed and secured
Equipment covers in place and secured
No evidence of impending failure

Table 130.5(C) Estimate of the Likelihood of Occurrence of an Arc Flash Incident for ac and dc Systems uses "normal operation" as a criteria to determine if there is a likelihood of an arc flash.

The link below is a video that I shot in the lab of a 400A bus plug with it's doors closed being blown open by an arc flash at 600 volts with 23,000 amps. If that happened while operating the switch i.e. interaction, "...closed doors do not provide enough protection to eliminate
the need for PPE"
Table 130.5(C) helps people make the determination if there is a likelihood of occurrence of an arc flash.

Video-Doors Blowing Open

-


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Fri May 04, 2018 1:13 pm 
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Thanks Jim. Do you have any idea on what the IE was?

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Barry Donovan, P.E.
www.workplacesafetysolutions.com


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Sun May 06, 2018 2:34 pm 
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wbd wrote:
Thanks Jim. Do you have any idea on what the IE was?


No, unfortunately this was part of a round of tests to determine arc behavior based on bus configuration/orientation. The next edition of IEEE 1584 has equations for different bus configurations.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Mon May 07, 2018 5:31 am 
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Thanks for the input.

So if doors being closed or open don't matter from a safety standpoint, why is it even a criteria? (Sorry, I'm a black and white person.)


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Mon May 07, 2018 8:05 pm 
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100questions wrote:
Thanks for the input.

So if doors being closed or open don't matter from a safety standpoint, why is it even a criteria? (Sorry, I'm a black and white person.)


It is about a reduced risk, not a reduced hazard.
If the doors are open there is a greater chance that an arc might be initiated.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Tue May 08, 2018 1:57 pm 
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JBD wrote:
100questions wrote:
Thanks for the input.

So if doors being closed or open don't matter from a safety standpoint, why is it even a criteria? (Sorry, I'm a black and white person.)


It is about a reduced risk, not a reduced hazard.
If the doors are open there is a greater chance that an arc might be initiated.


How? Please explain.

OSHA 1910.269 references whether or not the workers are within the MAD. MAD (minimum approach distance) is the term used in the reference standard for both OSHA and NFPA 70E and throughout IEEE standards but for some reason (professional jealousy) NFPA chose to rename it to "restricted approach boundary". Inside the MAD obviously personnel or tools can inadvertently push/move/make contact in some way or drop something where it does not belong. So obviously if personnel are outside the MAD the physical interaction is not going to happen. This eliminates the issue of dealing with open/overhead equipment in which there is no "door" as well as recognizing that there are many situations where a door might be open especially for observation/inspection/troubleshooting but the interaction risk does not exist. Whether the doors are open or not becomes immaterial since MAD does not exist with closed doors...this is a more general term. Using the "closed door" criteria doesn't work with outdoor/overhead equipment over even old open style exposed panelboards where quite literally often the only protection (if there is any) might be a "ballerina bar" handrail.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Wed May 09, 2018 6:37 am 
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PaulEngr wrote:
JBD wrote:
100questions wrote:
How? Please explain.

OSHA 1910.269 ...


The OP was about the wording in NFPA 70E -2015 130.7(15) Note 2 and normal conditions like in 130.2(A)(4)(4).


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Wed May 09, 2018 4:23 pm 
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My issue is doors closed is a necessary and sufficient condition and overly conservative but the converse (doors open is a necessary and sufficient condition for arc flash) is not. Tools and equipment outside the MAD is necessary and sufficient in the case of normal operation.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Thu May 10, 2018 5:06 am 
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Keep the discussion up. I'm learning. :D So to take this down to my level. This note is probably the reason why over time we've gone from a hazard risk catagory of 0 to 1 when it comes to operating a breaker in 208V panelboards "with the doors closed".


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Sun May 13, 2018 6:09 pm 
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Jim:

Hate to break it to you but EVERY SINGLE CASE in the 70E Tables used some sort of screwy version of "normal operation". Nothing in the tables actually ever used the "normal operation" definition. It's basically extraneous in the way it is written.

100questions wrote:
Keep the discussion up. I'm learning. :D So to take this down to my level. This note is probably the reason why over time we've gone from a hazard risk catagory of 0 to 1 when it comes to operating a breaker in 208V panelboards "with the doors closed".


If you use the table based method in 70E, "0" was eliminated so that moves you up to a minimum of "1" (4 cal/cm2).

Realistically going through every single case of arc flash in OSHA's more descriptive investigation database, I only found a single case where someone was purely operating a breaker and was injured. In that single case someone had previously "repaired" the panel by kind of loosely sandwiching sheet metal in the door to cover an opening but didn't actually secure it (screws, bolts, etc.) in any way. When the operator went to operate the breaker, the sheet metal fell into the busbars behind it.

Outside of OSHA there was a case about 15 years ago locally here where in a 480 V MCC operators turned a breaker on and off several times to reset a breaker that kept tripping on a pump. Never mind OSHA's stance on doing this. The electrician showed up and reset the breaker several times himself, then finally actually bothered to megger the motor to find it was dead shorted and commenced to replacing the motor. At no time was the breaker or the starter ever inspected. Once the motor was replaced, the breaker blew up on the final attempt to reset and close it back in and the electrician was burned by the arc flash. So obviously the breaker failed on the last attempt before making a repair and at no time was the breaker ever inspected as per NEMA AB-4 and none of these qualifies as "normal operation" since the breaker tripped, which should only occur for electrical faults.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Mon May 14, 2018 6:55 am 
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PaulEngr wrote:
Jim:

Hate to break it to you but EVERY SINGLE CASE in the 70E Tables used some sort of screwy version of "normal operation". Nothing in the tables actually ever used the "normal operation" definition. It's basically extraneous in the way it is written.


Agreed, "normal operation" has been a point of confusion that increased exponentially with the 2009 edition of NFPA 70E when "interaction" was added - not much clarification back then. I was referring to "normal" in the context of never being quite sure if the doors/covers would stay intact during an arc flash (from interaction/state change)or if the doors/covers/enclosure would block/reduce the incident energy during an arc flash even if they did stay closed i.e. don't rely on the doors. That is what I believe the note is addressing. Relating "normal" directly to the PPE Category Tables was not what I had intended.

It was the "changing state" comment that was focusing on. The 2015 edition (cited in the question) of the NFPA 70E handbook goes as far as to state:

"See the commentary following 130.2(A)(4) regarding normal operation. In most cases where normal operation is not involved and the state of the equipment is known to readily change -such as when taking off covers and exposing energized conductors and circuit parts, or racking in or racking out circuit breakers - PPE for the maximum possible hazard or other prospective techniques such as remote racking should be used." These action would NOT be considered normal according to the 6 criteria.

The referenced commentary in 130.2(A)(4) states "When equipment is considered to be operating normally, the risk associated with the normal operation is generally considered to be acceptable. There may be some unusual cases such as where rodents or snakes can get into the equipment through unsealed openings." This is considered normal according to the 6 criteria but there is still a caveat.

The breaker reset scenario can be (is) an issue - good one to point out. Typical case: Production is down, must restore, breaker has tripped, reset it - no questions. (or.... arbitrarily increase the setting then reset it. (what NOT to do in those last 7 words - I hope people don't take that as a procedure) Everyone must ask "why did it trip"

As my mentor and good friend often quotes, proper risk assessment should not include considering the phrase: "Do you feel lucky punk?" - Clint Eastwood - Dirty Harry.

Thanks for your comment and all the other great insights!


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Thu May 17, 2018 5:33 am 
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Thanks again for the input. I really do learn and get perspective from everyone on this board. I work on a large campus where 70E was implemented without any thought for it's affects on work practices or workers practices and after quite a few years of this "management" still hasn't understood we are NOT following 70E while they think we are and our biggest battle is due to one of the natures of man. E.g. Putting forth the least amount of energy to accomplish a task. This natural attitude when applied to knowledge of real world arc flash injuries tells most men they do feel lucky and the statistics prove them right. Don't get me wrong, I want to be safe BUT having to don PPE to open a 1P -- 20A - breaker in a small panel or opening a 60A disconnect on a small motor is almost a direct contradiction to our nature.

Jim -- I appreciate your mentors quote but I do have a question. When do the real world statistics come into play? From my vantage the lawyers and engineers :D have gone slightly over the edge on some of this stuff and have lost a lot of credibility in doing so.

PaulEngr wrote:
As my mentor and good friend often quotes, proper risk assessment should not include considering the phrase: "Do you feel lucky punk?" - Clint Eastwood - Dirty Harry.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Thu May 17, 2018 6:13 am 

Joined: Wed Jul 12, 2017 6:06 am
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100questions wrote:
Don't get me wrong, I want to be safe BUT having to don PPE to open a 1P -- 20A - breaker in a small panel or opening a 60A disconnect on a small motor is almost a direct contradiction to our nature


Has your site completed an incident energy analysis or are you using the table method? If you are having to don PPE to operate the items you mentioned above you should consider a full analysis. Very rarely are components that far down in the distribution system above 1.2 calories.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Thu May 17, 2018 8:27 am 
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ewbengineering wrote:
100questions wrote:
Don't get me wrong, I want to be safe BUT having to don PPE to open a 1P -- 20A - breaker in a small panel or opening a 60A disconnect on a small motor is almost a direct contradiction to our nature


Has your site completed an incident energy analysis or are you using the table method? If you are having to don PPE to operate the items you mentioned above you should consider a full analysis. Very rarely are components that far down in the distribution system above 1.2 calories.


We understand it is very rare that these items would likely have high IE. That's where human nature comes in. We probably have about 10 out of 150 buildings with anything close to a full analysis so in general terms we are on the table unless we are exceeding the max fault current for the tables. By the time I retire in 15 years they might be close to done. ;)


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Fri May 18, 2018 8:06 pm 
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One of the major causes of accidents is shown by the Clint Eastwood comment. As humans we're creatures of habit. So whatever the reason whenever we perform a task we do a self assessment on it. If we do not receive negative reinforcement, even of the painful kind, this reinforces that the particular behavior we did is good or at least not bad. So it reinforces the behavior until it becomes routine. The problem is that when we do something incorrectly and don't receive negative feedback for doing it (nothing bad happens), then it "validates" the incorrect behavior, even if what we did was to simply take a chance knowing that we're doing something incorrectly.

Second problem and this is where the statistics come into play. The arc flash injury rates according to say the data set ESFI reported are around 1 incident per 100,000 workers per year. I would contend based on some analysis that I've done (looking at causation) that the actual rates are even lower. The guy who did that analysis simply categorized anything as a "burn" injury involving electricity as an arc flash whether or not it also involved a shock. If you limit it to bonafide arc flash then the likelihood is much less. That's pretty rare...vehicular accidents have far greater probabilities as do a most other injuries. In fact electrical injuries as a whole are less than 1% of all accidents. I forgot the exact statistic but it's something like 43rd in the list of types of accident related injuries. HOWEVER when considering fatal accidents, it ranks 7th. So electrical injuries are comparatively rare but when they do happen, it's almost always really bad. A lot of risk assessments are based on the principle of the Heinrich accident triangle which says that for every fatality, there are 10 serious injuries, 100 minor injuries, 1000 first aids, and 10,000 near misses or something like that. Heinrich has been completely disproven and electrical injuries are no different because when they do occur, there are almost always severe.

The final issue as I see it is that as humans we have a really hard time estimating probabilities greater than about 1 in 100. We have a hard time estimating or grasping something that may only happen once in a thousand years or less. That being said generally speaking the risk assessment standards that exist generally push for serious accident or fatality statistics at a rate of between 1 in 100,000 and 1 in a million. As humans we struggle with and simply have a hard time visualizing what "1 in 100,000" or less even looks like. However there is statistical data out there to show that electrical equipment reliability is on par with those odds when it is in average normal functioning order. Thus there is statistical evidence for the concept of "normal operation" whenever operation is limited to operation of the equipment itself without direct human involvement. By this I mean for instance opening or closing breakers and switches almost always involves an overhanging cam that past a "point of new return" automatically moves to the closed or open position irrsepective of the condition of the breaker that it services. It's only when we start doing operations with direct human involvement such as working on the equipment while energized or racking operations that we cross the line since human error rates are around 10% on average. Thus both the task and the condition of the equipment (as can be readily determined by external inspection) can quickly prove whether or not the likelihood of failure meets or exceeds acceptable standards.


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 Post subject: Re: 2015 - 130.7(15) Informational Note 2
PostPosted: Mon May 21, 2018 5:31 am 
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Paul --- Very well put. Thank You.


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