It is currently Fri Feb 23, 2018 11:28 am



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: Heavy-duty leather foowear.
PostPosted: Sat Jan 24, 2015 6:18 am 
Offline
Plasma Level
User avatar

Joined: Wed May 07, 2008 5:00 pm
Posts: 711
Location: Rutland, VT
This may be a bit nit-picky but:

NFPA 70E-2015 Article 130.7(C)(10)(e) states “Foot Protection. Heavy-duty leather footwear provide some arc flash protection to the feet and shall be used in all exposures greater than 4 cal/cm2.”

whereas:

Table 130.7(C)(16) just lists Leather footwear

Is there a difference between Heavy-duty leather footwear and leather footwear? What constitutes the difference?

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


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Sun Jan 25, 2015 12:45 pm 
Offline
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 1880
Location: North Carolina
Same thing. I believe arcwear has done some testing. Obviously leather is not available/allowed in all situations.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Mon Jan 26, 2015 7:00 am 
Offline
Sparks Level

Joined: Tue Apr 03, 2012 1:28 pm
Posts: 51
Location: Louisville KY
We have tested leather work boots at Arcwear and standard leather work boots perform very well in arc flash situations. Leather in general performs well. The requirements per OSHA for a certain thickness is not defined. The only mention of footwear requirements in NFPA 70E are "where it is used..." in 130.7(C) (8) and the PPE categories of 130.7. The note in the 2015 version of NFPA 70E states that EH shoes meeting ASTM F2413 can provide a "secondary source of electric shock protection under dry conditions" and that standard does not mention a required leather thickness. The ASTM standard looks at impact resistance, compression rating, and metatarsal rating. A different section of ASTM F2413 mentions EH rating, and discusses the requirement to not exceed 3mA leakage current at 14KV for 1 minute under DRY conditions. I certainly would not put this to the test, but the shoe in a 480V situation should offer secondary protection with the user wearing or using other insulating material like voltage-rated gloves, etc. I have seen multiple arc flash tests on leather boots, however, and from solely looking at an arc flash issue, I would not be concerned for my feet in an arc flash while wearing a standard pair of leather work boots. This is by no means saying that the boot carries a certain arc flash rating.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Mon Jan 26, 2015 10:17 am 
Offline
Sparks Level

Joined: Mon Jun 07, 2010 9:40 am
Posts: 119
I think his question is more "Why is there a difference in language?" than "will leather do the job?"

If I remember correctly there is a similar vagueness about gloves too.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Mon Jan 26, 2015 10:29 am 
Offline
Sparks Level

Joined: Tue Apr 03, 2012 1:28 pm
Posts: 51
Location: Louisville KY
Like I stated earlier, the requirements per OSHA for a certain thickness is not defined. As for the language differentiation, your guess is as good as mine. I will make it a point to ask David Wallace tomorrow at the Electrical Safety Workshop if I can get his attention.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Mon Jan 26, 2015 10:36 am 
Offline
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 1880
Location: North Carolina
EH boots (which I thought were goiing to be dropped from OSHA regulations eventually) are given a specification for manufacturing but are not tested while in service so there is no guarantee they work after that, and as stated, only under dry conditions. They really aren't even secondary protection.

IEEE 516 is the original source given for shock hazards both for 70E and OSHA. IEEE 516 defines primary insulation as the material between the energized equipment and the worker which is closest to (or touching) the energized part. Secondary insulation is either any additional layers after the first layer, or if the worker is "floating", the layers between the worker and the reference or "ground". For example if a worker is using a hot stick AND rubber gloves, the hot stick is primary insulation and the rubber gloves are secondary. A worker operating from a bucket truck with rubber glove line work has the rubber gloves as primary insulation and the bucket truck is secondary insulation.

IEEE 516 mentions this but it is basic physics that when you have multiple insulation systems in series, the voltage is divided across them. However without knowing specific properties of materials at the interfaces, it is impossible to determine the voltage across each insulation system. It is not a simple "resistance" argument because the actual forces at work as capacitive in nature. Thus IEEE 516 requires all insulation systems to be fully rated for safety reasons.

EH rated shoes are not tested and only specified under dry conditions. Thus at best they might provide some sort of protection essentially by luck but definitely not by design. Thus they could never be treated as primary or secndary insulation under IEEE 516. They are at best a "feel good" effort. If shock is an actual concern of any kind, then I would flat out not even consider EH boots as any form of PPE at all. There is no requirement anywhere in OSHA regulations or anywhere else except for some Canadian standards recommending them.

DI boots (dielectric insulation) are specified and tested to an ASTM standard, essentially the same test as gloves, with a similar frequency of testing while in service. Thus although the DI boots must be fully rated as well, they are basically the same as rubber gloves. DI boots are required by some utilities as secondary insulation although this is rapidly falling out of favor due to the increaesd liability since you can't test a boot for holes (inflation test). The major use for them is when ground potential rise is a big concern but then again if it is, grounding mats provide a safer, OSHA recognized, alternative.

In static dissipative areas, DI and EH boots are strictly prohibited because they create conditions conducive to static discharges by insulating the wearer. In these areas, conducive footwear or straps with a metal strip that wraps around the boot is necessary.

Finally in chemical plants and other areas, rubber boots would be required. As an example close to home (next door to me here in the office) is a phosphoric acid plants. Leather is destroyed very quickly and the only recommended boot is neoprene. In the mine next door to that, rubber boots are pretty much a requirement when it gets muddy, slimy, and up to your ankles in water.

However, nne of these are tested for arc flash. So we don't have either an equipment specific or a category-specific rating unlike for gloves. There are lots of reasons that leather boots are undesirable for certain areas but so far no testing is out there in the public on them.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Mon Jan 26, 2015 10:54 am 
Offline
Sparks Level

Joined: Tue Apr 03, 2012 1:28 pm
Posts: 51
Location: Louisville KY
I totally agree with Paul. I would never trust my life to a pair of EH shoes - new or used. If I want protection, I will wear DI voltage-rated shoes or better yet, if possible, just de-energize. The fact that EH shoes are never tested or required to be tested after put into use says it all. I've had people tell me that they are in-fact required but then cannot back up that statement with any proof. They might be better than tennis shoes, but as Paul stated, they cannot be assumed to offer much protection. Working in wet conditions, around wet floors or outside, I will choose DI anytime.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Fri Jan 30, 2015 9:19 am 
Offline
Sparks Level

Joined: Tue Apr 03, 2012 1:28 pm
Posts: 51
Location: Louisville KY
I spoke with Dave Wallace (OSHA) to get clarity on this one. He said that OSHA recognizes no difference in leather and heavy duty leather work shoes/boots and neither does 70e.. He went further to state that any shoe rated EH would suffice but the shoe or boot must be a shoe or boot designed as a safety shoe or boot...in other words leather tennis shoes would yield a citation (Of course). Just wanted to share whar he said for clarity.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Tue Mar 17, 2015 11:21 am 
Offline

Joined: Tue Jun 18, 2013 5:00 pm
Posts: 7
In the spirit of clarity, the original question referenced leather & heavy-duty leather footware in terms of arc flash protection not shock hazard protection. What follows will align footware in terms of arcflash.

We seem to have established that we are not to be spoon fed the distinction between leather and heavy-duty leather by OSHA or NFPA or ASTM; leaving us with the sneeking suspicion that we were handed this void by tuncated NFPA 70E word-smithing.
The term "Heavy-duty leather" should be used in all cases.

in terms of Arc event and footware the considerations are:

wbd's original NFPA 130.7(C)(10)(e) sitation......heavy-duty leather footware for greater than or equal to 4cal/cm2 situations.

and
OSHA Protection from flames and electric arcs
OSHA 1910.269(l)(8)(v)(B)
"Arc-rated protection is not necessary for the employee's feet when the employee is wearing heavy-duty work shoes or boots,"

As insight to the OSHA labrinth can we make a leap of fathom to the hands and consider :

OSHA 1910.269(l)(8)(v)(A)
Arc-rated protection is not necessary for the employee's hands when the employee is wearing rubber insulating gloves with protectors or, if the estimated incident energy is no more than 14 cal/cm2, heavy-duty leather work gloves with a weight of at least 407 gm/m2 (12 oz/yd2),

this could offer a magnitude minimum threshold of leather density to look for in a boot for those who have a need to do so.

As for myself.....safety boots, not shoes. and careful selection of laces and trim.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Heavy-duty leather foowear.
PostPosted: Tue Mar 17, 2015 11:58 am 
Offline
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 1880
Location: North Carolina
70E arises out of Subchapter S. Or more precisely Subchapter S was an adaptation of 70E from a long time ago. Subchapter S is for utilization equipment.

The quotes are from 1910.269 which is subchapter R and applies to "generation, transmission, and distribution" equipment, or mostly utilities and some industrial sites.

You can't mix and match. 70E applies to Subchapter S and makes it clear in the scope. NESC is the counterpart for Subchapter R and also makes it clear in the scopoe. Both are explained (as well as can be explained) in the Appendix A to subchapter 1910.269 Appendix A. Don't just "google it" and expect correct results.

As to the whole footwear argument, it's something of a vague area. The intent of IEEE 1584 and indeed most of the arc flash standards is to analyze the threshold of a 2nd degree burn at the face/chest area, not ALL parts of the body, because severe burns to arms, hands, and feet are almost never fatal compared to burns to the face and chest areas. So by analogy even though much more research has been done in this area, there is really no attempt made to protect the hands from a serious arc flash because the incident energy is calcualted at the face/chest, not at the hands. Similarly feet are not generally protected either except in a vague way based on the references cited, at least by the standards.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 1 guest


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