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 Post subject: Define PPE 0, or "No arc flash PPE required"
PostPosted: Thu Oct 16, 2014 8:10 am 
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The 130.7(C)(15)(A)(a) tables in 70E 2015 now show a Yes or No for the Arc Flash PPE requirement.
If there is No requirement, I think that translates to PPE 0, which isn't defined in the 2015 edition.
What are you guys recommending for PPE 0?, the same thing that was listed in the 2012 edition for HRC 0? (130.7(C)(16)? That seems reasonable, but I may be missing it in the 2015 edition.
Thanks for any replies.
John M


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Thu Oct 16, 2014 9:06 am 
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mayanees wrote:
The 130.7(C)(15)(A)(a) tables in 70E 2015 now show a Yes or No for the Arc Flash PPE requirement.
If there is No requirement, I think that translates to PPE 0, which isn't defined in the 2015 edition.
What are you guys recommending for PPE 0?, the same thing that was listed in the 2012 edition for HRC 0? (130.7(C)(16)? That seems reasonable, but I may be missing it in the 2015 edition.
Thanks for any replies.
John M


That was my first interpretation based on the draft version. Now that the final version is here its not so clear at all. We had a very animated discussion with some of the E-Hazard guys over this a couple weeks ago.

I would give you an engineer's answer: it depends!

First off, non-melting clothing is NOT PPE at least the way that OSHA defines it. It's clothing. Calling it PPE is incorrect. OSHA also goes down this path with work boots. There are ordinary work boots and there are special work boots. Employers must pay for and/or supply special work boots but not ordinary ones. The difference is in what specific special features are required. Steel toes are not special but for instance dielectric overboots are.

There are two different reasons that there is a "no" result in the table, and that's where "it depends".

If the reason for a "no" is because the incident energy is low such as working on 120 VAC equipment, battery systems, etc., then the answer is "yes", wear non-melting clothing. In this case the goal is not so much to protect the worker as it is to avoid making any potential injuries worse. 1.2 cal/cm^2 is the standard we go by for arc flash and is based on the threshold limit for a second degree burn on bare skin. This immediately makes it clear that there's really no inherent difference between nonmeltable clothing (short or long sleeve) or being completely nude. The only caveat to this is avoiding clothing which can melt and stick and cause a much more severe burn.

If the reason for a "no" is simply because because an arc flash is very unlikely such as in the case of operating a circuit breaker, then the answer is "no", don't bother. If an arc flash occurs and anything less than the required level of PPE is being worn, the victim is in serious trouble anyways. Wearing inadequate clothing really won't make a lot of difference since the injury will be the same either way. Previous to 70E-2015 even the 70E Committee over and over again stated that "just walking by" was not an arc flash hazard. We did not need to paint yellow stripes on the floor and require anyone merely crossing the line to wear arc flash PPE. There wsa still a very small chance that an arc flash could happen spontaneously anyways and someone could be serious injured by "just walking by". Without the arc flash PPE there was also a small chance that the victim could be killed by such an event. The risk was negligible but in the event that it did happen, the victim would be completely unprotected. With 70E-2015 that same line of thinking has been extended further to consider all cases in which the task itself does not constitute "interacting with the equipment in such a way that could cause an arc flash". That doesn't mean that it can't happen. That doesn't mean that just the act of opening a door in one section of switchgear or an MCC can't set off enough of a vibration to cause an arc flash to occur in a completely unrelated section just by mere presence. Just as the act of simply opening the door on an electrical room could cause a small pressure change which could then move a conductor a very tiny amount and again, cause a "spontaneous" arc flash to occur. But we're got to recognize that there are generally 3 sources of "causes" for arc flashes:
1. Condition of the equipment and the environment. If the breaker just opened on a fault, there is a pretty good chance (according to ANSI standards for breakers) that it may have failed while opening. Think that this is just paranoia? It happened to a victim where I work now, less than 250 feet from my office.
2. Human error. Dropped tools, poor workmanship, losing control over a conductor, inspecting a conductor while moving it around, making an adjustment with a screwdriver and missing and coming off the head, thinking we are "Superman" and trying to do death defying feats of maintenance skill and foolhardiness. OSHA has documented mutiple cases of drilling and tapping ENERGIZED bus to install a breaker from a different manufacturer into a panelboard and causing an arc flash.
3. Background equipment unreliability. Equipment eventually fails, sometimes catastrophically. The only prevention is routine maintenance and inspections.

The former is very hard to predict. It is so hard to predict that reliability standards for mechanical equipment essentially give up and state that this is the major driving force. With electrical equipment "standard environmental conditions" are defined so that we can avoid this altogether and simply deal with the latter two.

Human error is a funny thing. There are a lot of external and internal influences that skew this number. A worker might be able to function normally one day, go home and have a fight with their spouse, and come back the next day and performance drastically suffers. Actual test work places human unreliability at somewhere around 1-20% with most practitioners averaging it out to 10%.

Finally, we have equipment reliability. Electrical equipment is actually extremely reliable. Failure rates are measured in unit-years and most equipment can operate successfully for decades of unit-years without incident. That doesn't mean that any given component can run for decades, but that the average as long as it is maintained (and replaced) properly over a large number of similar units is very good. In other words, electrical equipment is NOT INHERENTLY UNSAFE.

So now we come to consider arc flash PPE and whether or not it is necessary for all tasks. Certainly that's not true as a general rule. So the question is when is it necessary?

The answer is actually quite simple. Electrical equipment is very reliable. It is so reliable that unless there are known issues with it such as poor workmanship, it just faulted, water is running out of the panel, it is about to fall over, it is rusted out, etc., then it meets acceptable criteria for operation without PPE. There are two caveats that I'll get back to.

BUT, if the equipment is not maintained properly, not installed properly, or there is some obvious (visual inspection) reason to believe that it might not be meeting that criteria of low failure rates, then arc flash PPE is required.

And finally if the task at hand involves reliance on the skill of the person doing the work to avoid causing an arc flash in even a small way, arc flash PPE is required. Want to roll the idice and take a 10% chance that an arc flash occurs? I think not. What if it's 1%? 0.1%? So aside from obvious tasks like trying to make circuit modifications while the equipment is energized, inserting or removing equipment off an energized bus such as MCC buckets, busway plug-in devices, and draw-out switchgear gets counted at least in 70E as being too dependent on the reliability of the person doing the task.


Now you have three choices in this regard. You can copy the 70E chart and then mark it yourself as "tasks that require nonmeltable clothing" and "tasks that don't require nonmeltable clothing". Or you can choose to not require it at all, or you can choose to make it required for all electrical tasks.


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Thu Oct 16, 2014 10:12 am 
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Thanks for the discussion Paul.
That makes good sense, and reinforces the need to calculate the incident energy level.
I like that it's open to engineering interpretation, thereby giving us a prominent role in applying the standard.
John M


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Thu Oct 16, 2014 12:59 pm 
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mayanees wrote:
Thanks for the discussion Paul.
That makes good sense, and reinforces the need to calculate the incident energy level.
I like that it's open to engineering interpretation, thereby giving us a prominent role in applying the standard.
John M


Be careful with that. All risk assessment methods are pretty clear on how its supposed to happen. The recommended procedure is that you get a team together and you get adequate representation from safety, engineering, maintenance, etc. Everyone that's a stakeholder is involved. Then together you go through a process of looking at each task, what the hazards are, what the likelihood of the hazard is (without PPE, "maintenance switches", or any other kind of mitigation). Then if the risk is acceptable, you have at it. Otherwise you add the mitigation measures in and re-evaluate for the new risk. If its then acceptable, you move on. All the risk assessment procedures out there unless they are prescriptive in nature (PMMI is the most prominent example) have exactly the same procedure.

I've been through a lot of risk assessments either leading them or participating. I would honestly say that in 90-95% of the hazards that are evaluated, the decisions are quick and easy. For instance when doing visual inspections and not crossing the restricted approach boundary, no PPE needed. That one hardly requires any thought. When troubleshooting equipment right after it just faulted before anything has been inspected or when there is water running out of the panel, PPE needed. Those ones are easy. Then we get to ones like removing or installing MCC buckets or draw-out breakers. No we are working in the margins and we get into judgement calls on what should and should not be acceptable. These activities get into the very fringes of human errors and how much they really matter. As anyone who has done these tasks knows, it's a seemingly simple task and things don't go wrong very often. Its the old hands around the shop that have been there and done that and can tell you first or second hand what can and does go wrong that are important to listen to.

All that a risk assessment procedure does is try ts to first try to remove the emotion from what is an area fraught with knee jerk responses, and second to try to distill down that "tribal knowledge" as much as possible into real qualititive or semi-quantitative decisions. Otherwise, we get either "I've don't that 100 times before and never got hurt yet. What could possibly go wrong?" or "Electrical equipment is a death trap. Get our your Darth Vader suits and make sure your life insurance is up to date."

I'll give you a personal example and leave it with that, because there are multiple case histories in the OSHA logs of where this went very wrong. At a plant in New Jersey that has now been torn down they had a lot of old Cutler Hammer gear. How old? Back to when starters only required 2 overloads instead of 3 (pre 1970's vintage). Now many of the panelboards were so old that the newer style breakers don't fit in the older panel boards. You can modify them to fit though. You drill and tap the bus bars and you can make the newer breakers bolt in. In fact you can do this without shutting down the plant if you are very careful and slide a piece of rubber under the bus bar so that when the drill goes through it doesn't short the bus bar to the panel. And they had successfully done this not just once or twice but "once in a while". Good thing the drills these days have double insulation, right?? Care to guess at whether or not arc flash PPE should be worn? And should we even be doing this in the first place?


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Mon Oct 20, 2014 10:21 am 
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As always a big thanks to all of you for your insights, they are invaluable. The conversation so far has led me raise another question though. If through your risk assessment you have determined that even though the covers are on Arc Rated PPE should be worn aren't we now required by 130.2(2) to put the equipment into an "Electrically Safe Working Condition" unless we can justify energized work due to the greater hazard or infeasibility exceptions? And to chase this rabbit a little further if it is an older facility where very little documented maintenance has occurred how far upstream do I have to go to operate a switch with no documented maintenance even with PPE on that would satisfy 70E? Have the utility pull the high voltage fuses? Your thoughts on this matter will be greatly appreciated.


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Tue Oct 21, 2014 6:28 am 
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Please Don't forget, if you have the utility open the circuit, you should have it either grounded and tagged, or both to prevent another crew from coming by and closing it inadvently.


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Tue Oct 21, 2014 1:46 pm 
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John 60 wrote:
Please Don't forget, if you have the utility open the circuit, you should have it either grounded and tagged, or both to prevent another crew from coming by and closing it inadvently.


The majority of the utilities I have worked for/with have a tagging system in place which should prevent another crew from closing the fuses for some reason. Utilities and the lineworkers tend to follow very strict rules on tagging and removing tags.

Additionally I think some utilities may be reluctant to ground for other personnel especially if the fuses are the demarcation point. Of course if the utility owns the transformer they may be willing to ground on the transformer high side if they can open and lockout the secondary side main breaker. This follows the utility practice of having open points and would prevent any backfeed from a generator into a direct short.


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Wed Oct 22, 2014 5:50 am 
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graino wrote:
As always a big thanks to all of you for your insights, they are invaluable. The conversation so far has led me raise another question though. If through your risk assessment you have determined that even though the covers are on Arc Rated PPE should be worn aren't we now required by 130.2(2) to put the equipment into an "Electrically Safe Working Condition" unless we can justify energized work due to the greater hazard or infeasibility exceptions? And to chase this rabbit a little further if it is an older facility where very little documented maintenance has occurred how far upstream do I have to go to operate a switch with no documented maintenance even with PPE on that would satisfy 70E? Have the utility pull the high voltage fuses? Your thoughts on this matter will be greatly appreciated.


Not quite that bad. First and foremost, NOT doing any preventative maintenance is far more risky than doing it, even if its not the best program in the world. Qualitatively, probably over 90% of required electrical inspections are visual.

Second to answer your question, yes, 130.2(2) ALMOST applies. I really don't like the way that this is written but if you read further down into it, there are some exceptions. Diagnostic work such as online PM's or troubleshooting has an automatic "out" for requiring at least the written permit because obviously for instance you can't test for absence of voltage while in a "safe working condition" on equipment that is presumed energized until tested. Other similar things are for instance UV, IR, and ultrasonic testing...meaningless without energized equipment. Visual inspections also get a pass to a certain degree.

The more interesting problem here is whether or not opening doors hits the rule. In this case from a risk analysis point of view, I would suggest considering two cases. The first is where the door is a hinged door with a latch. It may or may not require using a tool to reach the interlock defeating mechanism that is commonly on MCC doors, where the only real hazard is stuff falling in or falling apart as the door is being opened or pinching wires while closing, all easily avoidable hazards. The second case would be for instance a circular cover such as a manhole where it is physically impossible for it to "fall" into the equipment and thus is very similar to the MCC door example. The third example would be a bolted cover such as the ones commonly on panelboards where it is pretty easy to accidentally drop the door inwards onto energized conductors. The risk of an arc flash is different for these two cases and thus your interpretation for doors at least for 130.2(2) changes. Why this is important is when doing PM's and other diagnostic activities opening and closing doors is often part of the procedure and seems to get folks hung up on it as a separate issue, rather than just looking at it as a subtask.

Finally with respect to your "how far do we have to go upstream" issue, I'd suggest this. From a failure analysis point of view, except in extremely unlikely circumstances, two pieces of equipment stand out. Fuses rarely fail in such a way that they take longer to trip or don't trip at all. It's not impossible, just very unlikely. The second is with load break disconnects. Statistically the same thing is true of these...they just don't fail that often. So these are two pieces of equipment that your analysis should indicate are more or less "unconditionally" safe. Then from a generic point of view we can consider other cases.

Finally, arc flash analysis usually stops at 2 seconds. So if you analyze the incident energy at 2 seconds, at least from a modelling point of view, this is the same as treating it as if the overcurrent protection doesn't exist. Time is linear from an arc flash point of view so you can recalculate this manually very easily as E=(original incident energy)*(2 seconds)/(original opening time).

Generally armed with these items you can look at your single line and quickly outline the equipment where you can quickly either rerate to a higher incident energy (if it changes at all), or where the overcurrent protection and/or disconnecting device allow you to safely perform the functions you need to do.


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Wed Jun 24, 2015 1:22 pm 
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PaulEngr wrote:
mayanees wrote:
The 130.7(C)(15)(A)(a) tables in 70E 2015 now show a Yes or No for the Arc Flash PPE requirement.
If there is No requirement, I think that translates to PPE 0, which isn't defined in the 2015 edition.
What are you guys recommending for PPE 0?, the same thing that was listed in the 2012 edition for HRC 0? (130.7(C)(16)? That seems reasonable, but I may be missing it in the 2015 edition.
Thanks for any replies.
John M


That was my first interpretation based on the draft version. Now that the final version is here its not so clear at all. We had a very animated discussion with some of the E-Hazard guys over this a couple weeks ago.

I would give you an engineer's answer: it depends!

First off, non-melting clothing is NOT PPE at least the way that OSHA defines it. It's clothing. Calling it PPE is incorrect. OSHA also goes down this path with work boots. There are ordinary work boots and there are special work boots. Employers must pay for and/or supply special work boots but not ordinary ones. The difference is in what specific special features are required. Steel toes are not special but for instance dielectric overboots are.

There are two different reasons that there is a "no" result in the table, and that's where "it depends".

If the reason for a "no" is because the incident energy is low such as working on 120 VAC equipment, battery systems, etc., then the answer is "yes", wear non-melting clothing. In this case the goal is not so much to protect the worker as it is to avoid making any potential injuries worse. 1.2 cal/cm^2 is the standard we go by for arc flash and is based on the threshold limit for a second degree burn on bare skin. This immediately makes it clear that there's really no inherent difference between nonmeltable clothing (short or long sleeve) or being completely nude. The only caveat to this is avoiding clothing which can melt and stick and cause a much more severe burn.

If the reason for a "no" is simply because because an arc flash is very unlikely such as in the case of operating a circuit breaker, then the answer is "no", don't bother. If an arc flash occurs and anything less than the required level of PPE is being worn, the victim is in serious trouble anyways. Wearing inadequate clothing really won't make a lot of difference since the injury will be the same either way. Previous to 70E-2015 even the 70E Committee over and over again stated that "just walking by" was not an arc flash hazard. We did not need to paint yellow stripes on the floor and require anyone merely crossing the line to wear arc flash PPE. There wsa still a very small chance that an arc flash could happen spontaneously anyways and someone could be serious injured by "just walking by". Without the arc flash PPE there was also a small chance that the victim could be killed by such an event. The risk was negligible but in the event that it did happen, the victim would be completely unprotected. With 70E-2015 that same line of thinking has been extended further to consider all cases in which the task itself does not constitute "interacting with the equipment in such a way that could cause an arc flash". That doesn't mean that it can't happen. That doesn't mean that just the act of opening a door in one section of switchgear or an MCC can't set off enough of a vibration to cause an arc flash to occur in a completely unrelated section just by mere presence. Just as the act of simply opening the door on an electrical room could cause a small pressure change which could then move a conductor a very tiny amount and again, cause a "spontaneous" arc flash to occur. But we're got to recognize that there are generally 3 sources of "causes" for arc flashes:
1. Condition of the equipment and the environment. If the breaker just opened on a fault, there is a pretty good chance (according to ANSI standards for breakers) that it may have failed while opening. Think that this is just paranoia? It happened to a victim where I work now, less than 250 feet from my office.
2. Human error. Dropped tools, poor workmanship, losing control over a conductor, inspecting a conductor while moving it around, making an adjustment with a screwdriver and missing and coming off the head, thinking we are "Superman" and trying to do death defying feats of maintenance skill and foolhardiness. OSHA has documented mutiple cases of drilling and tapping ENERGIZED bus to install a breaker from a different manufacturer into a panelboard and causing an arc flash.
3. Background equipment unreliability. Equipment eventually fails, sometimes catastrophically. The only prevention is routine maintenance and inspections.

The former is very hard to predict. It is so hard to predict that reliability standards for mechanical equipment essentially give up and state that this is the major driving force. With electrical equipment "standard environmental conditions" are defined so that we can avoid this altogether and simply deal with the latter two.

Human error is a funny thing. There are a lot of external and internal influences that skew this number. A worker might be able to function normally one day, go home and have a fight with their spouse, and come back the next day and performance drastically suffers. Actual test work places human unreliability at somewhere around 1-20% with most practitioners averaging it out to 10%.

Finally, we have equipment reliability. Electrical equipment is actually extremely reliable. Failure rates are measured in unit-years and most equipment can operate successfully for decades of unit-years without incident. That doesn't mean that any given component can run for decades, but that the average as long as it is maintained (and replaced) properly over a large number of similar units is very good. In other words, electrical equipment is NOT INHERENTLY UNSAFE.

So now we come to consider arc flash PPE and whether or not it is necessary for all tasks. Certainly that's not true as a general rule. So the question is when is it necessary?

The answer is actually quite simple. Electrical equipment is very reliable. It is so reliable that unless there are known issues with it such as poor workmanship, it just faulted, water is running out of the panel, it is about to fall over, it is rusted out, etc., then it meets acceptable criteria for operation without PPE. There are two caveats that I'll get back to.

BUT, if the equipment is not maintained properly, not installed properly, or there is some obvious (visual inspection) reason to believe that it might not be meeting that criteria of low failure rates, then arc flash PPE is required.

And finally if the task at hand involves reliance on the skill of the person doing the work to avoid causing an arc flash in even a small way, arc flash PPE is required. Want to roll the idice and take a 10% chance that an arc flash occurs? I think not. What if it's 1%? 0.1%? So aside from obvious tasks like trying to make circuit modifications while the equipment is energized, inserting or removing equipment off an energized bus such as MCC buckets, busway plug-in devices, and draw-out switchgear gets counted at least in 70E as being too dependent on the reliability of the person doing the task.


Now you have three choices in this regard. You can copy the 70E chart and then mark it yourself as "tasks that require nonmeltable clothing" and "tasks that don't require nonmeltable clothing". Or you can choose to not require it at all, or you can choose to make it required for all electrical tasks.


I had a similar understanding of when PPE was needed, however, I'm not so sure now based on the following from the latest 70E:

130.7(C) Personal Protective Equipment (PPE).
(1) General. When an employee is working within the restricted approach boundary, the worker shall wear PPE in accordance with 130.4. When an employee is working within the arc flash boundary, he or she shall wear protective clothing and other PPE in accordance with 130.5. All parts of the body inside the arc flash boundary shall be protected.

So, based on this, no PPE is needed if outside the RAB and outside the AFB. Is that a correct interpretation?

If so, help me reconcile the guidance in Informative Annex H that provides in Tables H.3(a) and H.3(b) PPE requirements for IE's exposures less than 1.2 cal/cm2, or when you are outside the AFB.

Table H.3(a) Summary of Specific Sections Describing PPE for Electrical Hazards
Arc Flash Hazard PPE (Applicable Section(s) not shown)
Incident energy exposures up to 1.2 cal/cm2
Clothing: nonmelting or untreated natural
fiber long-sleeve shirt and long pants or
coverall
Gloves: heavy-duty leather
Hard hat: class G or E
Face shield: covers the face, neck, and chin
(as needed)
Safety glasses or goggles
Hearing protection
Footwear: heavy-duty leather (as needed)

Table H.3(b) Guidance on Selection of Arc-Rated Clothing and Other PPE for Use When Incident Energy Exposure Is Determined
Incident Energy Exposure-Protective Clothing and PPE
≤ 1.2 cal/cm2
Protective clothing, non-melting (in accordance with ASTM F 1506) or untreated natural fiber-Shirt (long sleeve) and pants (long) or coverall

Other PPE - Face shield for projectile protection (AN)
Safety glasses or safety goggles (S)
Hearing protection
Heavy-duty leather gloves or rubber insulating gloves with leather protectors (AN)

Is this a backhanded way of defining normal work clothing to include non-melting long sleeves and pants, face shield, safety glasses, hearing protection, and heavy-duty working gloves even when you are outside the AFB? (forgive my inability to format the tables correctly)


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Mon Jun 29, 2015 11:52 am 
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Both boundaries have a rather tricky side issue to consider.

If there are no exposed parts (insulated, isolated, or guarded) there are NO shock boundaries at all. Not zero but they simply don't exist.

Similarly if the means of interacting with the equipment is not likely to cause an arc flash then again, there is NO arc flash boundary at all. Thus the new table has a bunch of cases for "normal work" scenarios where no arc flash boundary exists.

Either case causes the PPE to simply disappear as a requirement.

What we have in Annex H is that "H/RC 0" didn't get deleted and it addresses a 3rd possible case. That is the "low level arc flash", aka "H/RC 0". This would be for instance an incident energy of say 0.1 cal/cm^2. The tables now take the conservative approach and require a minimum 4 cal/cm^2 PPE when PPE is required. Annex H specifies PPE down to effectively zero.

The question is really whether or not for instance 0.1 cal/cm^2 could cause a serious injury based on whether or not meltable fiber clothing is being worn at the time. I don't really have an answer for this. I haven't deviated from recommending continuing the nonmeltable clothing requirement.


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Tue Jun 30, 2015 6:43 am 
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PaulEngr wrote:
What we have in Annex H is that "H/RC 0" didn't get deleted and it addresses a 3rd possible case. That is the "low level arc flash", aka "H/RC 0". This would be for instance an incident energy of say 0.1 cal/cm^2. The tables now take the conservative approach and require a minimum 4 cal/cm^2 PPE when PPE is required. Annex H specifies PPE down to effectively zero.

The question is really whether or not for instance 0.1 cal/cm^2 could cause a serious injury based on whether or not meltable fiber clothing is being worn at the time. I don't really have an answer for this. I haven't deviated from recommending continuing the nonmeltable clothing requirement.


I forgot the deleted HRC 0 PPE was where this came from. Thanks for the reminder.

Now that HRC 0 PPE has been deleted in the standard, the question from our workers is "for what used to be HRC 0 tasks an example being voltage testing or troubleshooting a panelboard with a calculated IE of <1.2 cal/cm2 (outside the AFB), besides shock PPE, what is the "required" PPE given that the information in Annex H is not a PPE requirement? Is there a requirement for everyday work clothing for <1.2 cal/cm2 tasks?


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Wed Mar 02, 2016 5:34 am 
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I'd like to repost this question since it went unanswered at the end of this discussion.

Now that HRC 0 PPE has been deleted in the standard, the question from our workers is "for what used to be HRC 0 tasks an example being voltage testing or troubleshooting a panelboard with a calculated IE of <1.2 cal/cm2 (outside the AFB), besides shock PPE, what is the "required" PPE given that the information in Annex H is not a PPE requirement? Is there a requirement for everyday work clothing for <1.2 cal/cm2 tasks?

I know the recommendation is for qualified workers to wear nonmelting clothing when no AF PPE is required or when outside the AFB and RAB, but is this a requirement?


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Thu Mar 03, 2016 9:03 am 
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I see there was a TIA No. 1128 proposal to add a note 2 to Table 130.7(C)(15)(A)(a) and (b) as follows:

Note 2: Clothing shall meet the nonmelting requirements of 130.7(C)11 and 130.7(C)12 when this table indicates arc flash
PPE is not required.

This seems like it would have answered my question in the previous post about whether nonmelting clothing is required if doing work and are outside the AFB. However, it appears the committee rejected the rationale of the proposal. See attached. So my question still stands, is there a requirement to wear nonmelting clothing as described in Table H.3(a) and H.3(b) for IE exposures <1.2 cal/cm^2?


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Fri Mar 04, 2016 12:50 pm 
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No justification.

This is another one of those rumors. Can you point to documentation on what the "minimum incident energy rating" of non-FR, non-melting fibers is?

I'll give you a small hint. Let's say we have a work shirt made of 12 oz. untreated cotton and a similar shirt made of the same material treated with the Westex process. Now let's test them in an ASTM 1959 "ATPV" testing method. How much higher will the incident energy rating of the FR treated material be? The physics here is simple. The thermal protection afforded to the worker is entirely due to the thermal properties of the bulk material. All that the FR treatment process is doing is to make it so that the material no longer sustains a flame. So the answer is that they will both hit around 10 cal/cm2. Hugh Hoagland's group just did a test on cotton shirts and verified that this is the case a couple years ago.

So what about nylon, polypropylene, etc.? I can't send you a report but similarly up until the point that it melts or ignites, it is going to be a pretty good thermal barrier, much better than bare skin.

So we come around to your question, what to do for <1.2 cal/cm2. Since the point at which "street clothes" actually ignite is quite a bit greater than the point at which a 2nd degree burn occurs, there isn't a hazard here. That's why "H/RC 0" was removed.

Now let's step it up and look at another situation. Let's say that someone is wearing a shirt rated for 10 ATPV and is exposed to a 10 cal/cm2 arc. At the chest area we're not going to get above 10 cal/cm2 and there is no second degree burn and no flaming/melting clothing. But if the arc happens while the hands/arms are in the enclosure, the exposure will be much higher than 10 cal/cm2. The shirt sleeves of the FR shirt may burn but won't ignite. How an undershirt responds to this condition is quite a bit different. There are plenty of videos on Hugh's web site among others showing various combinations of synthetic fabric winter jackets over FR PPE as well as the same scenario with the synthetics under the FR PPE.

So we have 70E in its current form...recommending nonmeltable clothing to be worn in combination with FR PPE but having no requirements at all when FR PPE is not required.


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 Post subject: Re: Define PPE 0, or "No arc flash PPE required"
PostPosted: Fri Mar 04, 2016 8:54 pm 
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Thanks Paul for a very enlightening response. I always enjoy your insight and perspective.


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