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 Post subject: What's missing in electrical safety news?
PostPosted: Fri Oct 24, 2014 7:29 am 
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Joined: Fri Oct 03, 2014 7:59 am
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Location: Iowa
I am new to The Arc Flash Forum. I work for Grace Engineered Products and we just started a new digital publication dedicated to news regarding electrical safety in an industrial setting. I'm curious about something and I hope you all will be able to help me by sharing with me your thoughts. What's missing in trade publications today with regards to electrical safety? What would like to see reported? Do you want more product profiles? More technical articles? More focus on safety culture?

As a wife of an industrial maintenance worker, I have a deep passion to help change the culture in the industrial world regarding safety, and specifically electrical safety. Thanks in advance for your input.


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 Post subject: Re: What's missing in electrical safety news?
PostPosted: Mon Nov 03, 2014 7:04 am 
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Hi Brandy

One thought could be is that no one is talking about electrical shock hazard out there. It seems as an electrical and OHS community we have become saturated with arc flash. Arc flash PPE, training etc... It is workplace electrical safety or as NFPA 70E is titled "Electrical Safety in the Workplace". Which means we need to be aware of both shock as well as arc flash hazard. Here in Ontario Canada the real issue and statistically it is proven that electrical shock or electrocution is what is causing injury to the electrical worker or associated trades- HVAC etc.

A good article on shock and shock protection may be of consideration. In my travels across Canada it is almost insulting the number of workers and supervisors who are unaware of things like a rubber insulated blanket, properly applied provides an approved barrier or means of protection from electrical shock particularly in the millions of panels out there with lack of finger safe technology.

Just a thought

Thanks


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 Post subject: Re: What's missing in electrical safety news?
PostPosted: Thu Nov 06, 2014 9:53 am 
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Shock is by far the greater hazard (shock injuries outweigh arc flash by a 2:1 margin), but it is well understood for the most part and the means to protect against it for the most part are fairly simple, and we have ready access to tools to study it. Arc flash captures the fascination of engineers because it is hard to deal with, not well understood, etc.

The only case with shock I'm thinking of where things get tricky is when you start considering ground loops and GPR (ground potential rise). There are so many variables involved that it is almost a case-by-case basis in some instances.

I think that in general, 70E started out OK and over the years is doing worse and worse in terms of shock protection because the general guidance it is going to is to have everyone wearing rubber gloves for all circumstances at all times. This goes directly against ALARP and is not generally a good idea. It does directly against live line tool methods that completely avoid exposure in the first place to say nothing of cover up methods. So the result is that employees either fight the rules which start pushing things like wearing rubber gloves with leather protectors to test for 120 V on a terminal that is "touch safe" using a meter with roughly 2 mm of exposed metal and the contacts are 12 mm apart. So the employees take more risks and start using for instance non-voltage rated tools to do work and start getting closer in general because hey, they're protected. Whereas if we followed IEEE 516, that NFPA 70E and OSHA REFERENCE as the shock protection standard, then we'd be encouraging as much use of live line tools (even the meter I just mentioned) as much as possible and not take unnecessary risks out of convenience if nothing else. Just recently they even removed reference to live line/bare hands techniques. I realize that few plants work at 69 kV or above but those who do probably should consider live line/bare hands. It is safer and work can be done quicker at higher voltages. That's the entire reason that the companies that use it are doing it.

As an example from IEEE 516 where the fascination with rubber gloves comes into play, consider a system operating at 50 kV. There is no rubber glove rated that high. But 70E says you gotta have them for ALL work, even if you are using a hot stick. The hot stick is rated for 100 kV per FOOT. Now 516 talks about "primary" vs. "secondary" insulation. If I wear the gloves and use the hot stick, I have effectively created a capacitive voltage divider where the voltage across the gloves is now X and the voltage across the hot stick is now Y. What voltage will I see? It depends on the material properties of the gloves and the hot stick. All is well and good as long as the voltage drop across the hot stick is enough to lower the voltage drop across the gloves below the voltage limit of the gloves, but what if it isn't? That is the precise reason that IEEE 516 requires that the voltage rating of all secondary insulation is equal to or greater than the voltage rating required if there was no primary insulation. So gloves can't be used in this instance.

Think that this all doesn't matter anyways because for all intents and purposes NFPA 70E stops at medium voltage? Think again. There are plenty of chemical plants, aluminum mills, steel mills, and mining operations that deal with this issue.


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