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 Post subject: Electrical hazard boots
PostPosted: Wed Feb 08, 2012 6:25 pm 
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As I understand it, there are EH boots (insulated), dielectric boots, static dissipative boots, and conductive boots. The only one that seems to be a requirement is that 70E talks about requiring dielectric boots for temporary grounding tasks only. This seems to fly in the face of IEEE 516 which definitely seems to recommend being grounded instead of being a floating object.

Are there any codes or particular recommendations out there for any of these? It seems like they get mentioned in various places as a "good idea" but there are no requirements aside from the one in 70E.


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PostPosted: Thu Feb 09, 2012 7:29 am 
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From OSHA:
[url='http://www.arcflashforum.com/owalink.query_links?src_doc_type=STANDARDS&src_unique_file=1910_0136&src_anchor_name=1910.136(a)']1910.136(a)[/url]
[INDENT=1]General requirements. The employer shall ensure that each affected employee uses protective footwear when working in areas where there is a danger of foot injuries due to falling or rolling objects, or objects piercing the sole, and where such employee's feet are exposed to electrical hazards.[/INDENT]
[url='http://www.arcflashforum.com/owalink.query_links?src_doc_type=STANDARDS&src_unique_file=1910_0136&src_anchor_name=1910.136(b)']1910.136(b)[/url]
[INDENT=1]Criteria for protective footwear.[/INDENT]
1910.136(b)(1)
[INDENT=1]Protective footwear must comply with any of the following consensus standards:[/INDENT]
1910.136(b)(1)(i)
[INDENT=1]ASTM F-2412-2005, "Standard Test Methods for Foot Protection," and ASTM F-2413-2005, "Standard Specification for Performance Requirements for Protective Footwear," which are incorporated by reference in ┬ž 1910.6;[/INDENT]

From ASTM F-2413-05:

Electrical shock resistant (EH) footwear is manufactured with non-conductive electrical shock resistant soles and heals. The outsole is intended to provide a secondary source of electric shock resistance protection to the wearer against the hazards from an incidental contact with live electrical circuits, electrically energized conductors, parts or apparatus.


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PostPosted: Thu Feb 09, 2012 6:34 pm 
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EH boots are good to 600 V. Dielectric boots can get up to around 15 kV. I don't recall seeing any that go higher.

Either way, according to IEEE 516 (the reference source for shock protection) this is called secondary insulation. It should never be used without primary insulation. In addition it's use converts the user into an object with a floating potential since induced voltages convert the user into a potential somewhere between the two voltage fields (usually line and ground). So contact with any other objects at any other potential at that point can be pretty hazardous.

So for that reason I'm struggling with when such protection would actually be a good idea. Last thing I want is to require EH boots to convert workers into floating objects because of a concern that they may be walking in wet conditions (and staying grounded) and then touch grounded equipment vs. being a floating object at an unknown but elevated potential and coming into contact with a grounded or energized object. Granted it's probably going to be only the energy that they've managed to store on the surface of their bodies as a capacitor that is being discharged but still...


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PostPosted: Fri Feb 10, 2012 8:00 am 
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Unless the worker is touching an energized part without primary protection (like gloves), his floating potential will not have much energy associated with it as you say. Touching a grounded object may induce a spark like static electricity. If the worker inadvertently touches an energized part, the insulated soles may prevent lethal current from flowing through his body. What would be a lethal shock with uninsulated soles may become a nasty painful shock.

Step- and touch-voltages during faults may be tolerable with insulated soles but fatal with uninsulated soles.


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PostPosted: Mon Feb 13, 2012 10:02 am 
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Here is the only article I know of written on this subject, if it helps.

http://ohsonline.com/articles/2011/04/01/using-dielectric-and-electrical-hazard-shoes.aspx

The links won't work since they are disabled on this site but you can cut and paste it if you want to read the article.


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PostPosted: Mon Feb 13, 2012 10:07 am 
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elihuiv wrote:
Here is the only article I know of written on this subject, if it helps.

http://ohsonline.com/articles/2011/04/01/using-dielectric-and-electrical-hazard-shoes.aspx

The links won't work since they are disabled on this site but you can cut and paste it if you want to read the article.



Link works fine - thanks for the article!


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PostPosted: Wed Mar 14, 2012 8:40 am 
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My impression is that standard "safety shoes" (leather, steel or, preferably, composite-toe) are adequate foot protection with HRC 2 and up. Another issue to consider is the employer payment issue. OSHA has long indicated that safety shoes are exempt from employer payment. Any indication that dielectric shoes or other specialty type shoes are required or needed would likely involve some type of feedback from OSHA or a requirement for employers to pay for these specialty shoes. I guess the bottom line for me is making it clear to employees that standard safety shoes adequately provide recommended protection for arc flash scenarios.


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PostPosted: Sat Mar 17, 2012 4:12 am 
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It is my understanding that EH shoes are required in Canadian jurisdictions, or at least that's how my Canadian counterparts understand it specifically in Saskatchewan Province. I don't know if this is federal or a specific provincial OH&S regulation.


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PostPosted: Mon Mar 19, 2012 6:30 am 
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PaulEngr wrote:
It is my understanding that EH shoes are required in Canadian jurisdictions, or at least that's how my Canadian counterparts understand it specifically in Saskatchewan Province. I don't know if this is federal or a specific provincial OH&S regulation.

Unless the company is of federal jurisdiction (banks, transport, communications, army and a few others), it is a provincial regulation. Utilities and manufacturing plants are of provincial regulations.


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