Equipotential Grounding

[safetyupnorth]

Has anyone heard about the study that PA Ben mentioned the OSHA group did on "equipotential grounding"? Apparently they are saying that E.G. is not as good as the original studies state. If in fact the use of a "shunt" around the worker is not going to provide a good enough path for the electricity travel so that the worker only sees a very small amount of current then it would be very nice to see the research.

[EyeNut]

Has anyone heard about the study that PA Ben mentioned the OSHA group did on "equipotential grounding"? Apparently they are saying that E.G. is not as good as the original studies state. If in fact the use of a "shunt" around the worker is not going to provide a good enough path for the electricity travel so that the worker only sees a very small amount of current then it would be very nice to see the research.

It wasn't an OSHA group that performed the study. It was American Electric Power (AEP), a large investor-owned utility. An article was published in the March/April 07 issue of Incident Prevention Magazine. The findings were sent to OSHA--doesn't mean OSHA validated them or will use them.

Read it here: http://incident-prevention.com/artic...AEP/Page1.html

[Bigheadnc]

Good Article.
Crap changes huh?

[PA BEN]

Has anyone heard about the study that PA Ben mentioned the OSHA group did on "equipotential grounding"? Apparently they are saying that E.G. is not as good as the original studies state. If in fact the use of a "shunt" around the worker is not going to provide a good enough path for the electricity travel so that the worker only sees a very small amount of current then it would be very nice to see the research.

Patriot
Member Join Date: Nov 2002
Location: wyoming
Posts: 90



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The feds should stay out of our business! I bet jump suits will be the norm unless you want to buy your own pants and shirts. WHatever is cheapest.

Also there is a study handed to OSHA contradicting equopentail grounding. Backed up by real studies, not trumped like the original tests.




It was Patriot that metioned the study not me. I asked what study?

[Koga]

Thanks for the article link! its intresting to read where someone (besides the company making the equipment) actually does a real test and finds something a little bit different. I always wonderd myself about the real effectiveness of a bar wrapped/ clamped around the pole below the linemans feet. As they found out it looks good in theory but in everyday work there are so many varibles its hard to say. For me nothing takes the place of my own 2 eyes seeing the opening tagging it open and flagging the pole. Testing and grounding at the opening. Then at any other potential source opening do the same. Then on each side of where we work we test and put a set of working grounds. Might take a little longer but so what, we get paid to do the job safe I will know the men and I will go home.

Koga

[safetyupnorth]

Thanks for replying and especially copying the link to the site. Its interesting reading. I am going to dig as deep as I can and try to get all of the facts supporting their study. I will keep everyone posted as chase this down.

In my opinion there are too many Linemen out there that don't show grounding the same level of respect they show their "rubber gloves". I don't blame just them for that because companies owe it to their employess to educate, train and then enforce rules, practices and procedures, as long as they are in place.

The more education that gets into the industry on grounding the better.

Be Consistent- always

[PA BEN]

QUESTIONING THE THEORY
AEP employees, while understanding the theory of equipotential grounding, questioned the effectiveness of the cluster bar to establish an equipotential zone on a wooden pole under all conditions. In 2005, management responded with formal testing at the AEP Dolan Lab facility outside of Columbus, Ohio.

What I find interesting is that the employees questioning a proven theory and management listing to them. Also if this test was done in 2005 why haven't we heard about it untill now?

[hillbilly]

Touche.... I aint real smart,but I was thinking the same dern thing.I believe you asked the perfect question.I was always wondered.....now I know,AEP sux

[500 KVA]

There has been a whole lot of experts in the industry (since the late 1950's) study this. The cluster bar is widely considered as the best method to give a lineman the best chance in an accidental energizing or an induction incident.

Then a utility from Ohio says they think something vastly different is the only way, and look at how many "LINEMEN" say, " AAAAh, Okay!" That's the way to do it.

I have seen information presented and the studies conducted for the use of a cluster bar. I have seen the math prove that it works. It makes sense to me.

The other way AEP claims to work does not. Until it is proven to me I'm not jumping on. It must be proven and not leave me with any doubts. Not just because someone said so.

The guys who say they believe it without hard facts to support itare just little sheep looking for the butcher shop.

[MAD's]

In New Zealand the powers to be are really starting to push this as well. Initially we were told to bond to the pole, wood or concrete, via a cluster bracket and this would help protect us during a single phase or induction event. The engineers told us that around 156 milliamps will kill most people and their tests had shown that during a livening event we could expect around 1800amps to flow around us. By using the cluster bracket around the pole this could reduce this to around 1500amps. When questioned about this and why should we bother as obviously 1500 is still a lot higher than 156 miliamps they got a bit upset. More recent testing by them has shown that to be effective the "cluster bracket" must reach or access the centre of the pole as this is were it is most conductive. It now appears that we will have to attach the brackets in such a way that we will achieve this i.e. brackets attached via at least 2 rods or screws accessing the centre of the pole. This may be achievable on the wooden poles but more thought will need to apply when concrete poles have to be climbed. Most of us have taken on board the concept of equipotential bonding but we question doing more durng the setup to protect ourselves when the engineers give us figures like the ones above that don't appear to be of help at all. Talk over here is maybe having to use insulated cover up gear and gloves during power shutdowns. Another line of thought is to have 2 physical breaks on each side of the work area were no other lines run in parralel or cross over or under. The use of 3 phase block earths on all sides of our work area will still apply.
Most of you guys work on wooden poles but if you have any experience / knowledge on how you acheive the equipotential work zone on concrete structures please share with us.