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 Post subject: PPE when doing voltage testing at metering cabinets
PostPosted: Fri Oct 24, 2008 8:57 am 
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Has anyone developed practices for taking voltage readings at metering cabinets or transformers? These areas could have a lot going on with the close proximity of primary and secondary. Voltage testing is a common practice in trouble shooting and needs to be done safely. I am looking for any ideas. If the metering cabinet isn't located by the transformer I would think that the incident energy would be just as bad if not worse (same current, longer time to interrupt) so I don't see this as a solution.

Any help much appreciated.


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PostPosted: Fri Oct 24, 2008 10:12 am 
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andrewh wrote:
Has anyone developed practices for taking voltage readings at metering cabinets or transformers? These areas could have a lot going on with the close proximity of primary and secondary. Voltage testing is a common practice in trouble shooting and needs to be done safely. I am looking for any ideas. If the metering cabinet isn't located by the transformer I would think that the incident energy would be just as bad if not worse (same current, longer time to interrupt) so I don't see this as a solution.

Any help much appreciated.


Not really sure what kind of answer you are looking for, not to sound like a smart ____ but have you looked at the NFPA 70E?


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PostPosted: Fri Oct 24, 2008 3:32 pm 
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Would need more details to answer. Metering cabinets could often have the meters fed by PT's and CT's, both of which will have high impedance and very limited fault current, as well as protected with fast fuses. So metering cabinets could be very low in IE. Taking voltage readings directly on a transformer bus would be just the opposite, with high fault current and long clearing times.


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PostPosted: Fri Oct 24, 2008 6:32 pm 
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Nfpa 70e

Exactly on point!!...and an issue near and dear to me....but we also need to keep in mind that if the equipment is utility owned, maintained, and controlled....while I agree that 70E can possibly provide some guidance, it absolutely does not apply to the installation.

My major concern is with self contained metering instalations, and especially with large 480 volt transformers.....what are the qualifications of the utility personnel setting and removing the meters. In many cases they are under the supervision of the financial/metering department and are not qualified by training or experience to be working in cabinets at that level.....and we all know what CAN and HAS happened.

Just had the same discussion with a client this week....and his words were "yes our people are probably not qualified".

Alan


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PostPosted: Sat Oct 25, 2008 5:11 am 
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Alan,

Our office park single phased this summer (I had that figured out and located the right transformer before the utility showed up). When they arrived this kid opens the transformer, sees a broken connection, and procedes to change it live, with no PPE besides rubber gloves. T-shirt and jeans. When I asked him about arc flash PPE he looked at me like I was babbling in some alien dialect.

I wonder what the Ei would be at that point? I understand the need to do this work energized, blackouts would be a part of daily life if they shut down sections of the grid for every repair, but some training and PPE is in order here, I felt sorry for this kid, I really dont think he had any idea of the danger he was in and what his life would be like (assuming he survived) if an arc flash happened.


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PostPosted: Sat Oct 25, 2008 9:13 am 
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I would expect this points back to employee attitude toward safety more than qualifications and training. I see and hear this constantly. Hot weather and they do not want to wear the PPE. He was obviously qualified as he did the repair without incident, but also did not follow safety rules which I bet are in place.

Even when we put them in long sleeves, they roll up the sleeves or take the shirt off in hot weather. Have been pretty successful at this point to get them to at least wear their hard hats, safety glasses, and gloves.

Even the NESC committee folks that I have talked with think to much is being made of utility arc flash as they do not believe the data exists to support more stringent rules. I do get concerned when we have a large 480 transformer but also know that it is unusual for a utility lineman to be severely injured or killed from a secondary fault.

I talk with the operating personnel about this at every opportunity and most always know of an instance of high voltage contact injury but none from arc flash. I am also not convinced at this point that requiring a linemen to wear uncomfortable and cumbersome PPE will not increase the chance of mistakes.

BTW....is your service voltage 208 or 480 and do you know the size of the transformer?

Alan


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PostPosted: Sat Oct 25, 2008 10:39 am 
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acobb wrote:
BTW....is your service voltage 208 or 480 and do you know the size of the transformer?

Alan



480V, I should have looked at the transformer size when he had it opened, but if I had to guess I would say 1000kVA


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PostPosted: Sat Oct 25, 2008 11:30 am 
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National Grid in Rhode Island has all linemen and meter personnel in Level 2 shirts and pants. They are some of the best trained both in safety and general knowledge I have ever worked with. So some utilities are getting it right.


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PostPosted: Sun Oct 26, 2008 7:20 am 
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I think most are getting it right when it comes to the line crews, but not as many with meter techs. Even with the training though, the problem I think is getting the employees to buy into the process. Getting them to understand that the employer is trying to do "for them" instead of "to them" is the challenge....that attitude thing again!

One of the main questions I get is "does this mean we are we going to have to wear long sleeves". After all, they do wear gloves to their elbows unless they are the 600 volt type. It is hard to argue with them when they have a collective experience of 50+ years in the business and have not seen the issues we are talking about.

Your thoughts?
Alan


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PostPosted: Fri Oct 31, 2008 7:34 am 
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Quote:
Taking voltage readings directly on a transformer bus would be just the opposite, with high fault current and long clearing times.


Yes, I am thinking of voltage readings directly on a transformer bus.

Quote:
One of the main questions I get is "does this mean we are we going to have to wear long sleeves". After all, they do wear gloves to their elbows unless they are the 600 volt type. It is hard to argue with them when they have a collective experience of 50+ years in the business and have not seen the issues we are talking about.


The rules/code all talk about head and torso, technically your arms aren't included, at least for the energy levels. The energy level on their arms is going to be greater then the torso. Unfortunately the rule makers must think your arms are expendable.


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PostPosted: Fri Oct 31, 2008 2:06 pm 
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Yeah, I know the standard only intends to provide protection from severe injury to the head and torso area seeming to not worry about losing the arms and hands. I do think if that was completely the intention, no one should need to wear a flash suit below the waist though.

It just seems prudent to me that if we are going to try to limit the damage, we should protect the arms as well. To that end, I guess what I was saying initially was that it is hard to argue that high voltage gloves and leather protectors would not provide better protection than an 8 cal long sleeve shirt.

Hence it seems to me that if the lineman is wearing gloves there is no need for the long sleeves.

Thanks,
Alan


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PostPosted: Mon Nov 03, 2008 2:03 pm 
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NFPA 70E-A2008:
130.7 (C)(6)(b) Flash Protection. Hand and arm protection shall be worn where there is possible exposure to arc flash burn. The apparel described in 130.7(C)(13)(c) shall be required for protection of hands from burns. Arm protection shall be accomplished by apparel described in 130.7(C)(5).

130.7(C)(5) is body protection.

Would insulating sleeves protect against arc flash? Seems like they are not mon-melting material and if they aren't covered by leather like gloves, they wouldn't do.


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