It is currently Thu Nov 23, 2017 4:56 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: HRC 0 question
PostPosted: Thu Aug 18, 2011 3:04 pm 
Offline

Joined: Mon Mar 29, 2010 8:31 am
Posts: 24
Location: Jonesboro, AR
If the Hazard/Risk Category is 0. Why are the requirements still a long sleeve shirt? To me it seem kinda silly to not recommend gloves or voltage rated tools for HRC 0, but still require long sleeves. Figure that regular working attire, including something like polo shirts, should still suffice. Kind of silly to make someone put on a long sleeve shirt just to operate a CB. If the condition is truely an HRC 0.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Fri Aug 19, 2011 6:21 am 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
Wormfood wrote:
If the Hazard/Risk Category is 0. Why are the requirements still a long sleeve shirt? To me it seem kinda silly to not recommend gloves or voltage rated tools for HRC 0, but still require long sleeves. Figure that regular working attire, including something like polo shirts, should still suffice. Kind of silly to make someone put on a long sleeve shirt just to operate a CB. If the condition is truely an HRC 0.


Becasue HRC 0 can get close to 1.2 cal/cm2 at which point 2nd degree burns of exposed skin can occur in 0.1 second. Plus arc flash PPE requirements are based on a assumed working distance (Usually 18") and your arm when operating a breaker is much closer than that and exposed to more heat(Which is why leahter gloves are also required).

The gloves and insulated tools are for shock protection and are a seperate issue, they are only required when there are exposed energized parts, arc flash PPE is required when working on energized equipment, exposed or not.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Fri Aug 19, 2011 8:05 am 
Offline

Joined: Mon Mar 29, 2010 8:31 am
Posts: 24
Location: Jonesboro, AR
If there is a chance of an Arc Flash then wouldn't you be in the arc flash boundary and be subjected to 130.7 (C)(1) "an employee working within the Arc Flash Protection Boundary they shall wear PPE in accordance with 130.3", which in the 70E handbook says one way to determine PPE is to use tables 130.7(C)(9), 130.7(C)(10) and 130.7(C)(11).

That leads me to believe, that if the HRC level is actually 0 you have to be working on equipment that meets the notes of the tables, or be outside the arc flash boundary. If your exposed to IE of 1.2 cal/cm2, then 130.7(5) kicks in and says you have to be wearing FR clothing. So then why a long sleve shirt if there is an HRC 0 condition? Seems like they are saying, there is still a hazard (which is true), but so is walking for some people.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 24, 2011 5:27 am 
Offline

Joined: Fri Oct 30, 2009 9:20 am
Posts: 47
Location: Texas
Personally, I don't like the implication of category zero. HRC 0 is clearly defined in the standard; however, when most of us think of zero we think of absolutely nothing there - take your checking account balance for instance. I believe that psychologically categories 1 through 5 would have been a better choice than 0 through 4.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 24, 2011 11:20 am 
Offline

Joined: Mon Mar 29, 2010 8:31 am
Posts: 24
Location: Jonesboro, AR
You hit my take on the HRC levels on the head, and stated it well.

TY


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 24, 2011 7:10 pm 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
George wrote:
Personally, I don't like the implication of category zero. HRC 0 is clearly defined in the standard; however, when most of us think of zero we think of absolutely nothing there - take your checking account balance for instance. I believe that psychologically categories 1 through 5 would have been a better choice than 0 through 4.

I agree 99%, I would have 0-5 with 0 meaning naked :)


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 25, 2011 6:34 am 
Offline

Joined: Mon Jan 31, 2011 6:28 am
Posts: 14
This is strictly regarding the HRCs in the NFPA 70E right? If an incident energy analysis is done, anything below 1.2 cal/cm2 does not require PPE. However, the NFPA 70E Article 130.7(C)(1) states that 'all parts of the body inside the AFB shall be protected'. This implies that if your AFB is calculated to be 6", you would ONLY need leather gloves, but could be allowed to wear a short sleeved shirt.
I think that HRC 0 (or Level 0 PPE) is being misused in the field when doing an incident energy analysis.
Incident energy is calculated at a working distance of 18" to prevent loss of life. How close do we have to calculate to protect an individual finger? Hasn't the temperature at the arc terminals been known to reach 35,000 degrees F? How does a leather glove protect against that?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 25, 2011 8:30 am 
Offline

Joined: Mon Mar 29, 2010 8:31 am
Posts: 24
Location: Jonesboro, AR
My take on it is this. HRC 0 is not 0 PPE, it is as stated in the table long sleeve shirt, pants, safety glasses, hearing protection, leather gloves (as needed). Still have to wear shock protection if what your doing could be subjected to a shock hazard (Qualified person should be able to determine that). Could be argured that certain CB are not finger safe and should be operated with gloves.

My point is that it is way to easy for people to jump from HRC 0 to 0 PPE, and that it would be better stated if they started the HRC level at 1, and if your truly in a situtation where there is no flash hazard, and virtually no shock hazard (CB at 24V) why require a long sleeve shirt? I guess if someone got shocked by doing this the company could still be subjected to general duty clause established by OSHA (regardless of the NFPA 70E).


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 25, 2011 9:43 am 
Offline

Joined: Mon Aug 11, 2008 5:00 pm
Posts: 24
Zog wrote:
I would have 0-5 with 0 meaning naked :)


I'm gonna have nightmares! :eek:


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 25, 2011 11:22 am 
Offline

Joined: Mon Jan 31, 2011 6:28 am
Posts: 14
Wormfood wrote:
My point is that it is way to easy for people to jump from HRC 0 to 0 PPE, and that it would be better stated if they started the HRC level at 1


I 100% agree with this, but I'm starting to get frustrated because this misconception (HRC 0 vs. PPE 0 for < 1.2 cal/cm2) seems to be taking over the industry. IE calculations are done at 18" to prevent loss of life from arc flash. If we start saying that calculations have to be done at 6" to protect hands when operating a CB or a fusible disconnect, I feel like we're going beyond the intent of the code.
Furthermore, with this issue in mind, why are we allowing workers to wear leather gloves for PPE level 2 when their hands are likely going to be at a level 3 or 4 and Arc Rated gloves should be worn? The only difference between them is 'exposed skin', but will leather gloves matter in a blast that big?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 25, 2011 1:19 pm 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
m_cmbl wrote:
I 100% agree with this, but I'm starting to get frustrated because this misconception (HRC 0 vs. PPE 0 for < 1.2 cal/cm2) seems to be taking over the industry. IE calculations are done at 18" to prevent loss of life from arc flash. If we start saying that calculations have to be done at 6" to protect hands when operating a CB or a fusible disconnect, I feel like we're going beyond the intent of the code.
Furthermore, with this issue in mind, why are we allowing workers to wear leather gloves for PPE level 2 when their hands are likely going to be at a level 3 or 4 and Arc Rated gloves should be worn? The only difference between them is 'exposed skin', but will leather gloves matter in a blast that big?


Actually arc testing on leather gloves (Protectors used for rubber gloves) has excellent protection qualities, something around 80 cal/cm2 if I recall. Of course there is no testing standard approved for these gloves so no actual numbers can be applied but they offer a lot of protection. I believe Hugh Hoadland (A member here) did some informal testing at KEMA on these gloves.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 25, 2011 1:26 pm 
Offline

Joined: Mon Jan 31, 2011 6:28 am
Posts: 14
Zog wrote:
Actually arc testing on leather gloves (Protectors used for rubber gloves) has excellent protection qualities, something around 80 cal/cm2 if I recall. Of course there is no testing standard approved for these gloves so no actual numbers can be applied but they offer a lot of protection. I believe Hugh Hoadland (A member here) did some informal testing at KEMA on these gloves.


Wow, that's good to know! Thanks for the info :)


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Aug 25, 2011 6:29 pm 
Offline
Plasma Level

Joined: Mon Jun 02, 2008 11:58 am
Posts: 1103
Location: Charlotte, NC
m_cmbl wrote:
Wow, that's good to know! Thanks for the info :)


Here is the report, some excellent work was done here. But remember this was just an experiment, these gloves don;t really have "arc ratings".
http://www.arcwear.com/arcwear.com/downloads/Salisbury_2002-04_Glove_Test_Report.pdf


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 2 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:  
cron
© 2017 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883