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 Post subject: Labels for <240V, 3p??? I don't think so...
PostPosted: Thu Feb 18, 2010 9:15 am 

Joined: Thu Aug 20, 2009 9:50 pm
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Location: PA
I've seen a number of posts similar to this, but I'd like some opinions...

Assume we've got a number of 208V, 3p panels... a number of 120VAC, 1p panels... all are: rated 240V or less and supplied by one transformer that is less than 125 kVA.

Hence, an arc flash hazard analysis is NOT required.

Therefore, no labels need be applied to these panels.

Anybody disagree with this? If so, why/based on what?

Thanks in advance for the opinions...


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PostPosted: Thu Feb 18, 2010 9:42 am 
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Location: New England
Nec 110.16.


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PostPosted: Thu Feb 18, 2010 12:00 pm 

Joined: Thu Aug 20, 2009 9:50 pm
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Location: PA
Ahhhh... I should have been more precise in my question!
I would say that no labels listing an HRC or the Incident Energy need to be applied to those panels.

Would you agree with that?

Of course for a new installation, the "generic" labels would be required (and would likely be applied by the manufacturer)...

For an existing installation, the "generic" labels... hmmm... well I guess that's going to be question #2.

If performing an AFHA for an existing facility, would you recommend "generic" labels be applied to EVERY piece of equipment that is excepted by NFPA 70E from the AFHA?


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PostPosted: Thu Feb 18, 2010 10:52 pm 
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I would say that you SHOULD list the minimum HRC or IE. The purpose of labelling is to provide awareness that you need to use caution and special PPE. While you don't have to do analysis, that does not mean you do not need some level of protection, the lowest level being Level 0. So for this I would list PPE Level 0, Incident Energy 1.2 cal/cm. Some businesses have a minimum level for any work, say Level 1. If that is the case then on the label I would put Level 1, 4.0cals/cm.

The NFPA write both NEC and 70E. So, NEC is going to have a requirement for PPE and or IE in 2012 (I bet). So do it now. That will also be interesting because, Arc Flash Art 130 is not law, only a means to avoid being fined under the General Duty Clause. NEC is almost always adopted by each State and thus becomes law, State Law.

I can just see NFPA doing that end run.


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PostPosted: Wed Mar 03, 2010 11:17 am 
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This one still gives a lot of people heartburn.

The short history is IEEE 1584 made a statement about not needing to study circuits on transformers < 125 kVA and less than 240 volts. This was because at the time it was believed the low short circuit currents on the secondary side of a small transformer combined with the low voltage of 208 volts would not result in much of an arc flash.

NFPA added similar language in the 2009 Edition of 70E but included 240 volts.

In recent years a couple of things have happened.

  • Lab tests show under certain conditions there could be a potentially dangerous arc flash at these levels. I was part of some of this testing and pretty openly talk about it in my arc flash calculation study training classes.
  • A question has arisin that since this is partially a "low current" issue, what about very long high impedance circuits off the secondary of larger transformers. The current could also be low. Using kVA seemed like a good idea at the time since a similar method is used in short circuit studies but now many of us beleive an actual current cut off would be better.
  • IEEE 1584 is about to undergo a revision based on several years of new information. One of the areas to be addressed (I am the one responsible for coordinating this one within 1584) is the 125 kVA 208V cut off issue.
  • People are assuming there is not hazard. One organization (I won't say who) gave me a copy of a page of their safety practice where they were going to label the equipment "No Arc Flash Hazard" Of course I immediately intervened.


So what all this means is a casual assumption spun off in many directions. A pretty well respected member of NFPA 70E proposed an emergency deletion of this language in an attempt to solve the problem but I believe many thought that might be an over reach. There is some middle ground - we are just not sure where it is yet.

Where I see this headed is ultimatley there will be a lower limit of short circuit current not transformer kVA limit where we can reasonably say it is a low incident energy. Right now we don't know where that limit is but tests are still on going.

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PostPosted: Sat Mar 06, 2010 12:11 pm 

Joined: Sat Mar 06, 2010 10:04 am
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Fct

How does the FCT (Fault Clearing Time) impact the hazard for 208 V? Use of software on the market many times reflects hazard category 3 for 208 v panelboards. This is with a Category 1 on the 480 side. The 208 V panelboards are fed from a small transformers 480-208/120. The high side breaker is not good at protecting the panelboard and many times the panelboards are MLO type. Regardless of MCB or MLO type, the rating would be the same for a panelboard since the line side hazard would rule. Are you implying that 208 volt should use a different formula, or that a better rule regarding gap distance and working distance be applied? My understanding is NFPA is concerned that 208 volt can be dangerous and cause injury. I agree but can these really be a category 3 as the software predicts? NFPA has done testing to prove this, but I'm not aware of any specific published findings - are you? I also understand IEEE is not so fond that the 1584 standard implies do nothing at 112 kva and smaller, and I suspect this will be changed. Many folks I run across say at 208 V or at 112 kva I do not have to be concerned - this is an unfortunate false impression (and ignores the greater then 50 v requirement elsewhere in NFPA & OSHA) that is widespread. Folks are citing the IEEE as the basis. I find it hard to believe that IEEE has not responded - are you aware of any formal response?: One IEEE member advised just use the 2 second time. Sometimes this works and sometimes it doesn't, but I would not want to rely on the reflexes of an individual stunned by a flash. confused:


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PostPosted: Sat Mar 06, 2010 12:19 pm 

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I would label every Switchgear, Switchboard, MCC, Panelboard, Fused Disconnect, Meter Enclosure, Control Panel, etc. Anywhere that an employee or contractor may be asked to go to open a cabinet to do work. As an employer, you want to make sure you are notifying the worker of the hazard and the appropriate safety precautions. Existing & new equipment. Regargless of what NEC 110.16 says, OSHA will not care if it is new or old equipment if there is an injury. Aslo - make sure everyone is doing a Job Hazard analysis whenever equipment is opened up energized, regardless of the task. Do not forget splice boxes and manholes if you routinely open these.


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PostPosted: Mon Mar 08, 2010 3:07 pm 
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Rocky wrote:
How does the FCT (Fault Clearing Time) impact the hazard for 208 V? Use of software on the market many times reflects hazard category 3 for 208 v panelboards. This is with a Category 1 on the 480 side. The 208 V panelboards are fed from a small transformers 480-208/120. The high side breaker is not good at protecting the panelboard and many times the panelboards are MLO type. Regardless of MCB or MLO type, the rating would be the same for a panelboard since the line side hazard would rule. Are you implying that 208 volt should use a different formula, or that a better rule regarding gap distance and working distance be applied? My understanding is NFPA is concerned that 208 volt can be dangerous and cause injury. I agree but can these really be a category 3 as the software predicts? NFPA has done testing to prove this, but I'm not aware of any specific published findings - are you? I also understand IEEE is not so fond that the 1584 standard implies do nothing at 112 kva and smaller, and I suspect this will be changed. Many folks I run across say at 208 V or at 112 kva I do not have to be concerned - this is an unfortunate false impression (and ignores the greater then 50 v requirement elsewhere in NFPA & OSHA) that is widespread. Folks are citing the IEEE as the basis. I find it hard to believe that IEEE has not responded - are you aware of any formal response?: One IEEE member advised just use the 2 second time. Sometimes this works and sometimes it doesn't, but I would not want to rely on the reflexes of an individual stunned by a flash. confused:


There is no official IEEE response yet but there will be someday - I am the one responsible for re-evaluating the 125 kVA exception. It was really added back in the 2002 document based on the belief that low current, low voltage i.e. 208 would not sustain therefore time was not much of an issue regardless of the protective device. Most of the time that is probably correct but a few people (me being one of them) have found certain conditions in the lab that can sustain the low current low voltage arc)

NFPA has not done any tests. This was suppose to be covered with the IEEE/NFPA joint project but I understand it has not been covered so far. That is why a few of us decided to take it on ourselves. We did some "scouting tests" (see what happens) in January. We were quite surprised at the unexpected results, i.e. we got it to sustain and release a significant amount of incident energy. I hope to be getting more involved with this but unfortunatley it takes a lot of time.

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PostPosted: Thu Mar 11, 2010 9:00 am 
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JLY wrote:

Hence, an arc flash hazard analysis is NOT required.

Therefore, no labels need be applied to these panels.



OSHA 29CFR 1910.132(d)(1) The employer shall assess the workplace to determine if hazards are present...

OSHA does not exclude 208V panelboards in general industry regardless of the transformer rating. They may not be an arc flash hazard but they are a shock hazard and require an assessment.


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PostPosted: Thu Mar 11, 2010 9:07 am 
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Grandfathered?

haze10 wrote:
Nec 110.16.


What about a plant that was built in 1950? The NEC requires labeling today but didn't when the plant was built. Do we now have to go back and bring this facility up to today's code. I don't believe we do... unless of course it is modified.


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PostPosted: Thu Mar 11, 2010 9:15 am 
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haze10 wrote:
So, NEC is going to have a requirement for PPE and or IE in 2012 (I bet).


Including PPE requirements in the NEC does not coincide with its scope (90.2). If you will recall, Chapter 4 (Installations) in the NFPA 70E 2004 edition was removed because it did not pertain to its scope which addressed those electrical hazards that are necessary for the practical safeguarding of employees.

NEC (NFPA 70) = Safe Installations
NFPA 70E - Employee Safety

When information overlaps between the 2 publications the risk for contradiction and confusion will rear its ugly head.


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PostPosted: Mon Mar 29, 2010 5:09 am 
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Rocky wrote:
I would label every Switchgear, Switchboard, MCC, Panelboard, Fused Disconnect, Meter Enclosure, Control Panel, etc. Anywhere that an employee or contractor may be asked to go to open a cabinet to do work. As an employer, you want to make sure you are notifying the worker of the hazard and the appropriate safety precautions. Existing & new equipment. Regargless of what NEC 110.16 says, OSHA will not care if it is new or old equipment if there is an injury. Aslo - make sure everyone is doing a Job Hazard analysis whenever equipment is opened up energized, regardless of the task. Do not forget splice boxes and manholes if you routinely open these.



Firstly, being new here, I'd like to say hi to everyone and I'm looking forward to doing some more reading and becoming more knowledgable on Arc Flash...

I agree with this post to an extent.. Right up until "spilce boxes".. I am assuming that the author was referring to large splices on the feeders to planels. Not to 4x4 boxes, utility boxes, etc.. Otherwise there would be labels on every light switch...


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PostPosted: Mon Mar 29, 2010 7:26 pm 
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I don't think he meant 4sqr boxes. I also wouldn't label a manhole, as I would have no idea where I would put the label. Manholes tend to be very controlled, with preplanning and permit only entry. Splice boxes are another, assuming this is a large enclosure for splicing of power cables, I would have to assume those splices are all 'insulated' and there are no live components in the splice box, so I wouldn't label a box which only contained insulated wires.


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PostPosted: Tue Mar 30, 2010 4:54 am 
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haze10 wrote:
I don't think he meant 4sqr boxes. I also wouldn't label a manhole, as I would have no idea where I would put the label. Manholes tend to be very controlled, with preplanning and permit only entry. Splice boxes are another, assuming this is a large enclosure for splicing of power cables, I would have to assume those splices are all 'insulated' and there are no live components in the splice box, so I wouldn't label a box which only contained insulated wires.


I would label a splice box (such as: MF2-SB1). That way it can be referenced on plot plans, electrical drawings, and notes. As you mentioned the wires are insulated, and if there are no live parts inside, further labelling shouldn't be needed (client specific of course)... Any reference to what is inside would be found on the electrical drawings where it is noted..


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PostPosted: Tue Mar 30, 2010 9:19 pm 
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By all means you can label the enclosure, but i thought the initial reference to 'label' implied an arc flash label.


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