It is currently Thu Feb 22, 2018 9:20 am



Post new topic Reply to topic Go to page 1, 2  Next
Author Message
ekstra   ara
 Post subject: Normal operations
PostPosted: Wed Jul 21, 2010 9:37 am 
Offline

Joined: Wed May 12, 2010 1:43 pm
Posts: 4
My plant is about to start arc flash training and normal operations seems to be a problem. We have had a study done and 95% of our plant is Cat. 0 which makes it easy for the electricians. The problem is for the line operators who have to lock out there equipment for changeovers and use push buttons that are mounted in the panels for normal machine operation. It appears that because this equipment is 480V these people would also have to have PPE. This seems like over kill and lessens the importance of arc flash to those it could help. If pushed a case could be made that a secretary would have to change her close to turn on her 277V light switch. I have seen this discussion before but it was last year and I hoped there would have been some clarification by now.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 22, 2010 10:56 am 
Offline
Sparks Level

Joined: Mon Dec 14, 2009 4:24 pm
Posts: 61
My understanding is that there is disagreement between "very cautious vs. realistic" camps within the 70E committee. There is no concrete guidance in the standard that I am aware of.

Our organization will be going to a risk-hazard approach where the hazard category is decremented based on risk. Flipping a light switch would be considered "extremely" low risk.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 17, 2010 12:28 pm 
Offline

Joined: Fri Sep 05, 2008 8:10 am
Posts: 36
I am interested in the risk-based strategy. This is what was done by the committee when creating the table in 130.7(C)(9). I would be interested in following this approach as it would ease PPE requirements, I am having trouble justifying this method. Just because something has low to extremely low risk how can I feel comfortable using less PPE.

For example if analysis determines a panelboard is 8.4 cal/cm2, HRC 3. If I am voltage testing do I wear HRC 2 or 1? If an incident occurs I am still exposed to 8.4 cal/cm2 even though the risk of it happening is low. I don't mean to pick on anyone in particular as I've heard of others following this methodology. I am hoping someone can explain to me where this comes from. This method seems to diverge from the standard of "better safe than sorry".

Thanks you for any assistance.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 17, 2010 4:08 pm 
Offline
Sparks Level

Joined: Mon Dec 14, 2009 4:24 pm
Posts: 61
The hazard/risk approach comes from the fact that you cannot reasonably protect against every hazard. There is a risk that you'll have a heart attack triggered by getting out of bed in the morning, but the risk is so low that we (or most of us) do it anyway without any precautions. Similarly, driving is a significant hazard and we do it in spite of the hazard. The risk is significant so we use a seat-belt. By the same reasoning it isn't practical to walk around a plant wearing a suit of plate-metal medieval armor, but you probably wear a bump cap and safety glasses.

The risk of an arc flash event changes depending on the type of interaction. Consider opening a panel door to expose a dead front. Could an arc flash happen at the exact moment you opened the door? Sure. But the odds are pretty damn low. The hazard/risk approach to arc flash PPE is valid if it is developed by qualified personnel and trained and documented as part of your overall safety program.

Of course this advice was free and you get what you pay for, your mileage may vary and smart people might disagree... :)


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 24, 2010 6:38 am 
Offline

Joined: Thu Jan 07, 2010 6:42 am
Posts: 35
Location: Bowling Green, KY
[font="Comic Sans MS"][SIZE="3"]MIEngineer,
There is a Electrical Safety Compliance Chart for NFPA 70E and CSA Z462 available from Cementex: http://www.cementexusa.com/pdf/WallChart_small.pdf
It tells you HRC's for various voltages and tells what PPE is required for tasks. It takes the questions away! :D [/size][/font]


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 25, 2010 1:55 pm 
Offline

Joined: Wed May 12, 2010 1:43 pm
Posts: 4
The table illustrates the problem. There are tasks with such low risk anyone should be able to do them without PPE. I should be able to reset a 20 amp breaker in a 240V panel, with the covers on, in a (short sleeve) tee shirt and shorts. It is probably being done a hundred times an hour somewhere in the US right now. So instead of just stating this in the table everyone has to make their own rules to deal with these very low risk situations. Somewhere a house framer’s air compressor just blew a breaker, does he need to switch shirts and change into pants to reset it? 70E says yes, he needs to be in Category 0 not shorts and a tee shirt.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 26, 2010 9:14 am 
Offline

Joined: Fri Sep 05, 2008 8:10 am
Posts: 36
All,

I was reviewing the NFPA 70E-2011 Report on Proposals. Does the following suggest that the committee does not agree that once an Incident Energy Analysis has been performed PPE must be based solely on those findings for all tasks? Thus not allowing a risk-based strategy? If that is the case where is the benefit of performing the Incident Energy Analysis and not stopping at the Short Circuit study so that the tables may be used?

**Please look at the official copy as the formatting doesn't carry through to this forum.**

http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70E


70E-246 Log #391 EEW-AAA Final Action: Reject
(130.3(B))
_______________________________________________________________
Submitter: David A. Pace, Olin Corporation
Recommendation: Revise 130.3(B) to read as follows: Where is has been
determined that work will be performed within the Arc Flash Protection
Boundary identified by 130.3(A), one of either or both of the following
methods shall be permitted to be used for the selection of personal protective
clothing and other personal protective equipment.
Substantiation: There are cases when methods to calculate incident energy are
not available and the only method left is through use of the tables. Also, even
when calculations are used, PPE determined to be suitable for use is derived
from the tables based on the calculated energy level. Information input into
software packages on proper PPE comes from the tables in 70E. To say the
analysis has to be done by one method or the other, but not a combination of
both, is impractical as it is essentially being done already.
Committee Meeting Action: Reject
Committee Statement: NFPA 70E does not permit mixing methods of
selecting personal protective equipment. If incident energy calculations are
performed, Tables 130.7(C)(9), (C)(10), and (C)(11) cannot be used for
selection of personal protective equipment. Incident energy values shall be used
for selection of proper PPE.
Number Eligible to Vote: 25
Ballot Results: Affirmative: 22 Negative: 1 Abstain: 1
Ballot Not Returned: 1 Selk, A.
Explanation of Negative:
PACE, D.: This proposal should have been Accepted. The committee
statement does not address the submitter’s substantiation. If there is no method
available to calculate incident energy, as is the case with some equipment, there
is no other method other than the tables. Using the committee statement’s logic,
every electrical distribution system would have to use the tables rather than
calculations because not all equipment is covered by calculation methods, and
the mix of the two is prohibited. This is being done today as there is no other
source for the information. Using the tables to assign a HRC number does not
impact the selection of PPE.
Explanation of Abstention:
WALLIS, D.: I am abstaining in accordance with Agency policy against
voting on technical issues.
_______________________________________________________________


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 26, 2010 9:54 am 
Offline
Sparks Level

Joined: Mon Dec 14, 2009 4:24 pm
Posts: 61
Good question.

To me it looks like this ROP addresses a slightly different question about using the *NFPA* tables in conjunction with IE results from a study.

NFPA PPE recommendations from the table are based solely on the task and voltage level with some caveats in the notes under the table, not incident energy.

I don't see anything that prohibits use of a hazard/risk approach, you just have to develop it yourself and base PPE on the task and calculated incident energy.

Or maybe I'm reading it wrong... Anyone else care to comment?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 26, 2010 8:03 pm 
Offline
Arc Level

Joined: Wed Jun 04, 2008 9:17 am
Posts: 411
Location: Spartanburg, South Carolina
It seems to me that since this proposal was rejected, the Committee does agree that once an Incident Energy Analysis has been performed PPE must be based solely on those findings for all tasks.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 7:32 am 
Offline
Sparks Level

Joined: Mon Dec 14, 2009 4:24 pm
Posts: 61
But the scope of the proposal was specifically the NFPA tables and not broadly targeted at use of a hazard/risk approach.

I don't see how this ruling would prohibit you from using the calculated incident energy in combination with task risk to develop PPE recommendations based on both hazard and risk.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 9:16 am 
Offline
Plasma Level
User avatar

Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1245
Location: Scottsdale, Arizona
Maybe I am reading too much into this but to me it seems like the "mixing" of methods is that you perform incident energy calculations when you can and base the PPE selection on Table 130.7(C)(10) and (C)(11) like almost everyone does including most software.

We all know you can NOT mix calculations and Table 130.7(C)(9) which are the Hazard Risk Tables but I don't think this issue was part of the proposal.

In areas where you CAN NOT perform calculations (for whatever reason), you use use the HRC's of Table 130.7(C)(9) with, (C)(10) and (C)(11).

The above makes sense to me except this hits that long running arguement that I have with NFPA when they say you can not mix tables and calculations and they take it to mean you can not mix (C)(10) and (C)(11) with calculations. I think we all know not to mix (C)(9) with calculations but adding (C)(10) and (C)(11) to that arguement does not make sense.

This is a pretty common approach. Perform calculations for as much of the system as you can and areas where you can not, use the HRC table 130.7(C)(9).

_________________
Jim Phillips, P.E.
Brainfiller.com


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 10:41 am 
Offline

Joined: Fri Sep 05, 2008 8:10 am
Posts: 36
brainfiller wrote:
We all know you can NOT mix calculations and Table 130.7(C)(9) which are the Hazard Risk Tables but I don't think this issue was part of the proposal.


brainfiller wrote:
I think we all know not to mix (C)(9) with calculations but adding (C)(10) and (C)(11) to that arguement does not make sense.


These are the points I am struggling with. I have heard of an approach to say "Use the calculated IE or table 130.7(C)(9), whichever is LESS" or to take the calculated IE and lower the PPE requirements based on the risk such as "regardless of the calculted IE operating a CB with the doors closed never requires over HRC 0." Are these incorrect approaches according to NFPA 70E? Or is it simply the risk the Facility would be willing to take on and be able to justify it were an incident to occur?

I don't mean to belabor the point but what is the incentive to perform the Incident energy analysis and not stop at the short circuit study to verify that I can use table 130.7(C)(9)?

Thanks to all for your continued experience and perspective in this.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 11:08 am 
Offline
Sparks Level

Joined: Mon Dec 14, 2009 4:24 pm
Posts: 61
MIEngineer wrote:
I have heard of an approach to say "Use the calculated IE or table 130.7(C)(9), whichever is LESS" or to take the calculated IE and lower the PPE requirements based on the risk such as "regardless of the calculted IE operating a CB with the doors closed never requires over HRC 0." Are these incorrect approaches according to NFPA 70E?

I don't mean to belabor the point but what is the incentive to perform the Incident energy analysis and not stop at the short circuit study to verify that I can use table 130.7(C)(9)?


For the first question - I guess you could do that, but you could not then say that you are in compliance with NFPA 70E. You cannot use the NFPA 70E task tables once the I.E. has been determined from a study. I THINK you can develop your own risk reductions based on the task, but that isn't spelled out in 70E.

For the second question - The incentive to perform the I.E. analysis is to estimate arc flash hazard. OSHA says that employers have a duty to protect employees from hazards in the workplace. If you do a short circuit study and stop right there it (rightfully) looks like you are trying to subvert your responsibility to protect employees by ignoring the hazard. I believe that would be considered a willful violation.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 12:37 pm 
Offline
Plasma Level
User avatar

Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1245
Location: Scottsdale, Arizona
MIEngineer wrote:
These are the points I am struggling with. I have heard of an approach to say "Use the calculated IE or table 130.7(C)(9), whichever is LESS" or to take the calculated IE and lower the PPE requirements based on the risk such as "regardless of the calculted IE operating a CB with the doors closed never requires over HRC 0." Are these incorrect approaches according to NFPA 70E? Or is it simply the risk the Facility would be willing to take on and be able to justify it were an incident to occur?

I don't mean to belabor the point but what is the incentive to perform the Incident energy analysis and not stop at the short circuit study to verify that I can use table 130.7(C)(9)?


130.3(B) leaves it up to (1) calculations or (2) Hazard/Risk categories. The motiviation of using the calculations is that they are system, equipment and location specific. Calculations frequently show that areas where the HRC was high such as category 4 (as in inserting an MCC bucket) may actually be much less. However, the opposite may also be true. The HRC system was from 2000 and since then we have the IEEE 1584 calculation method.

The approach of taking the lesser of the calculation or HRC is a dangerous approach. If NFPA 70E shows HRC 0 and the calculations indicate 25 cal/cm^2 (just as an example) I would not want to be the one performing the work in category 0 protection.

_________________
Jim Phillips, P.E.
Brainfiller.com


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 12:53 pm 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
brainfiller wrote:
The approach of taking the lesser of the calculation or HRC is a dangerous approach. If NFPA 70E shows HRC 0 and the calculations indicate 25 cal/cm^2 (just as an example) I would not want to be the one performing the work in category 0 protection.


Or the one that said it was OK to wear HRC 0. My understanding, from talking to some of the 70E commitee guys, is that once you have identified the hazard (Ei) you have to protect your employees from that hazard level with the PPE based off the analysis and can no longer use the tables on that piece of equipment.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 1:01 pm 
Offline
Arc Level

Joined: Wed Jun 04, 2008 9:17 am
Posts: 411
Location: Spartanburg, South Carolina
I don't believe that the intent of 70E is to prevent using IE calculations for part of the facility and using Table 130.7(C)(9) for other parts. 130.1(B) says "one of the following methods shall be used..." 130.3(B)(2) says that the tables "shall be permitted to be used..." I don't see anything that says that you can't use the tables if you know what the IE is.

Also, 70E-A2011-ROP includes the following:

70E-244 Log #120 EEW-AAA Final Action: Accept
(130.3(B))
_______________________________________________________________
Submitter: E. W. Buss, Mashpee, MA
Recommendation: Add to the end of the paragraph...”protective equipment :
for each work task:
Substantiation: Some users interpret the existing paragraph to mean that the choice of either an incident energy analysis or the use of the tables is a facility wide decision; that if you do an incident energy analysis for most of the facility, you cannot use the tables for other parts of the facility. This proposal eliminates this interpretation; a user will be able to use either for a specific task. The method used still needs to be documented as noted earlier in the paragraph “... and the employer shall document”. Even when a complete system calculation is done, it does not mean that the calculation has to extend down to each and every 120 v circuit. For those cases the use of the tables should be acceptable.
Committee Meeting Action: Accept


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 4:27 pm 
Offline
Sparks Level

Joined: Mon Dec 14, 2009 4:24 pm
Posts: 61
I just found notes from an NFPA 70E training on the 2009 standard that was given by the NFPA last year. They seem relevant.

"The intent of the standard is that when an incident energy calculation is done the recommended PPE will be developed based on the IE and the tasks done by the organization."

To me that says that the employer is supposed to use the incident energy and their own task tables that take the specific task and incident energy into consideration.

It is the employers responsibility to take the incident energy information and use it intelligently to recommend PPE.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Aug 30, 2010 5:27 pm 
Offline
Sparks Level

Joined: Tue Feb 24, 2009 7:05 am
Posts: 252
Annex F (could be another one like Annex J, I don't have my copy of 70E with me) talks about how to build a hazard/risk approach to PPE selection. I haven't heard about a facility actually using it. There could be some major liability issues with that.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 31, 2010 6:26 am 
Offline
Arc Level

Joined: Wed Jun 04, 2008 9:17 am
Posts: 411
Location: Spartanburg, South Carolina
Vincent B. wrote:
Annex F (could be another one like Annex J, I don't have my copy of 70E with me) talks about how to build a hazard/risk approach to PPE selection. I haven't heard about a facility actually using it. There could be some major liability issues with that.


Has anyone on this forum actually used Annex F to develop custom task tables? I can't make enough sense out of this Annex to feel the least bit confident in any task tables I could create. There is a complete revision to Annex F in the 2011 ROP that seems to be much more complete.

I'd be interested in seeing an actual application of Annex F.

IMO, the effort involved and the liability questions make a custom hazard/risk analysis out of the realm of reality for a consultant. Maybe a large company could devout the time and resources to such an undertaking.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Aug 31, 2010 7:59 am 
Offline
Sparks Level

Joined: Mon Dec 14, 2009 4:24 pm
Posts: 61
My (large) organization is currently evaluating a risk/hazard approach. The process under consideration involves the following:

1) Assign a hazard category for the equipment based on incident energy. This category goes on the label. In our case the categories are identical to those used in the 70E task table; 0-4 with the same brackets for I.E..
2) As part of the job hazard analysis determine the risk of the task.
3) Decrement the hazard category based on the risk of the task.

For example opening a panel cover to look inside is considered low risk. If the worst case incident energy corresponded to a "Category 2" hazard behind the dead front, the worker could decrement that category by two units and use "Category 0" when selecting PPE for the task of opening the panel without entering the enclosure.

Yes, this approach would be hard to implement for companies that do not have a training infrastructure, but training is a fundamental aspect of 70E. The employer can't hire a consultant to put labels on the gear, walk away and be considered compliant.

Yes, I suppose there is liability involved. My thinking is that you have to balance caution with reason.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 4 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