What does equipotential grounding do for me

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Information about What does equipotential grounding do for me

Published on March 1, 2014

Author: TimVassios

Source: slideshare.net

What does equipotential grounding do for me? The Presumption: Once grounds are in place the worker is safe from any risk of electrocution. The Standard: “Protective grounds shall have an impedance to ground low enough to guarantee prompt operation of protective devices in case of accidental energization of the lines or equipment.” The Intention: If properly applied, equipotential grounding should quickly trip the fuse, recloser, interrupter, breaker, or other ‘upstream’ protective device of the energizing circuit. (Presuming that particular protective device operates as expected and has been programmed or ‘set’ properly.) Presuming the worker is within the zone of protection during the time it takes to trip that device, the grounds may minimize the difference of potential between the worker, the object(s) he/she may be in contact with, the pole, and/or the conductors that have been intentionally ‘grounded’; if all of these variables work together as intended the employee shall then expect to be properly protected from severe injury from being shocked or death by electrocution. The Reality: We routinely place our lives ‘on the line’; Linemen are at their best when conditions are at their worst. When the potential for danger is high we respond with a heightened sense of responsible behavior for ourselves and the public we protect. BUT I have seen and am just as guilty of letting my guard down when the grounds go up. Most of us know better, the real question is can we teach all of what we know to the next generation. I speak from experience by stating more is caught than taught. We Journeymen need to be demonstrating proper procedures as we explain why we do what we do. The Problem: The electric utility industry saw this day coming, we need linemen, yesterday! Most are expert at a specialized aspect of the trade, typically outside overhead transmission and distribution construction. Very few spend effort to care, let alone know, and subsequently can’t teach the similarities of the underground systems. Instead they focus on the differences and ignore the reality that outside of the current major investor market

driven transmission projects that nearly 70% of the rest of the infrastructure going in is underground, and that ratio will continue to rise. Many markets exist where the underground is almost 100%; these linemen begin to lose their overhead skills. But it does not have to be a win-lose situation. The industry needs competent trained professional Journeymen Linemen who can do both, well. We can teach that, but we need people who know and an environment built for it. The Reaction: There is a line school popping up in every county and on every junior college campus across America. Some utilities have created alliances with institutions of higher learning and advertising themselves as partners with the latest green job promotions. All claiming to teach what the industry needs, yet often do not have a real understanding of that need is. Especially when it comes to URD, underground sub-transmission, and underground transmission, let alone substations or network systems. They are focusing on the problem (things) and not the solution (people) and trying to build a showcase for receiving Federal grant money on green renewable power and ignoring the facts, or planning for the future beyond this current ‘trend’. Because that is all it is, when the consumer figures out green power is more expensive power the trend will change by demand, it is just simple economics of supply and demand. We can do both, receive the grants for the renewables now (giving them what they want). And we can be ready to provide for the future (giving them what they need). The picture of this is the windmill and solar array on display as a badge in front of any organization that is doing this. There are a select few that do so for the right reasons, and those reasons are what needs to become contagious.

The Result: Today’s apprentices are coming into the trade and herded through a program/any program at an alarmingly accelerated rate. The lineman of yesterday oftentimes received their status as a Journeyman after a decade or more ‘in the trade’. Working their way through the ranks, drawing irreplaceable experience and knowledge observing, listening to, and learning from the Journeyman they grunted for; until finally after showing the ‘right stuff’, they were selected to begin an apprenticeship and were able to ‘hit the pole climbing’ as they soared their way through their training. Most of the trainees today have no foundation in the field of electrical construction. Many have never worked in the field; have little to no mechanical aptitude and poor physical ability. More and more of them are coming out of these schools attempting to re-invent a second or third career path. The age of today’s apprentice lineman ranges from the rare teen to men and women well into their 20’s, 30’s, 40’s, and even into their 50’s! Very few of today’s lineman apprentices have a solid base of knowledge on which to build. The Solution: “Treat every job, every task, and every encounter as a teachable moment that lives depend on. The life you protect may be your own. No matter their background, or lack thereof, treat every apprentice and every linemen with the same level of dignity and respect you would expect your son or daughter to receive if they were to pursue an apprenticeship. The quality of the future of this trade rests

squarely on the shoulders of us who find ourselves the seasoned Journeyman of today. We must overcome the obstacles of the multigenerational workforce, oftentimes having to teach people who are older than ourselves. Just as importantly the older generations must be prepared to learn something from the new kid too.” The Example: The process of getting a line grounded to work on starts long before the cluster bar is sent up the hand-line. This is exasperated when you are dealing with a combination of underground and overhead lines on the same circuit or work location. Power authorities today focus on self-preservation through lawyer driven administrative control procedures of the switching authority. If as much effort went into training the lineman to perform the work safely we would not have to spend so much time and money training the worker to comply with CYA policies. These ‘control measures’ are giving the youngsters today a false sense of security that the utility version of the ‘lock-out’ tag-out’ system is their ‘safe work practice’. Nothing, nothing can replace critical thinking and sound decision making based upon principles of power instead of blind administrative compliance. No hold card, stop card, caution, card, or clearance tag ever brought a person back from the dead. But it sure makes it easier to write smaller check when they can find the un-dotted ‘I’ and un-crossed ’t’.

“In my experience as a lineman, a trouble man, foreman, supervisor, and now an instructor trainer; I have stopped being surprised by the lack of critical thinking that occurs before, during, and especially after grounds are in place. I like to teach the whole process so that the apprentice gets a thorough understanding of how linemen take methodical ‘baby’ steps to resolve issues and minimize exposure risks. Each step in the process of getting a line grounded is a confirmation of the success of the preceding step.” Starting with a circuit map, teach your apprentice to be able to read, comprehend and understand every symbol, all the terminology and the nomenclature used by your utility. Oftentimes the best source of learning is with the people who produce your maps; drafting, engineering, GIS or whomever is the ‘keeper’ of the maps is a good place to glean all that they know about them. It is often a lot of information that must be absorbed in pieces but none the less critical for the next step. Have your apprentice look over the map while they are looking at the section of line in question. These two pictures are worth two thousand words and often times help to create some real ‘aha’ moments of map reading and comprehension for the future. Have your apprentice check in with the switching authority to see if they are looking at the most recent update of that particular map page (presuming at this point you are still on paper and not on real-time digital mapping). Confirm that there are no abnormal switching conditions than what is indicated on the map and if so, make note of them on the map. Allow your apprentice to work through ‘on paper’ a switching routine, making sure to initiate request for the appropriate hot line hold orders and clearance requests for the affected circuit(s) or any circuit which could potentially energize the section of line you wish to ground. Some utilities do not ‘overlay’ all of their distribution, sub-transmission or transmission maps in one single viewable source. It is important to look at these mapping sources as well. Once you make your suggestions and provide your apprentice with the correct information to request a switching routine help them submit the request. Once the switching routine is completed let your apprentice work through it again, on paper, to make certain they see, understand, and agree with all of the steps of the switching order. This is a critical error I have seen countless times: When we perform switching we are not to be robotic hands of the system operator who blindly obey each order without thought or consideration for what we are about to do. Regardless of your company policy, when lineman physically closes or opens any part of the system, even at the direction of someone else, that lineman must be prepared to accept the results of that action. We are trained to repeat back what we have been ordered to do and to acknowledge we understand before we operate the system. This is the ‘checks and balance’ of knowing what we are doing and being aware, capable, and prepared to hold up any part of the process which could have devastating consequences. If you switch enough, you inevitably be a part of something that

will go wrong. It is not a matter of if, but when. Can you live with yourself better knowing you may have saved an error, or wasn’t paying attention and missed something simple? Speaking of switching, teach your apprentices to know their live line testers inside and out. Show them to care for them as if their lives depend on it. Too many times I see live line testers tossed about, bounced around, not tested, not calibrated, and even broken but still in use. And, if your utility permits test point testers for URD or voltage detectors, teach your apprentices to use these as ‘indicators only’. They have value for use in switching procedures to make testing efficient and to minimize live line exposure. However, they should not be relied upon for testing line de-energized and this should be done only by an approved liveline tester with an actual ground reference that has been proven to be functioning immediately before use on a known power source. Extremely frightening are the Journeyman who do not know what a test-point is, let alone understand the difference between a capacitance cap and a shipping cover on a bushing. Over and over I see seasoned Journeyman rely on a test point indicator when they switch URD elbows. They work fine so long as you expect and see an ‘energized’ indication. When

your elbow test point indicator shows ‘de-energized’ you must now presume that you have one of many things going on, some possibilities are: 1. You may indeed have de-energized cable. 2. You may have a non-functioning test point indicator. 3. The test point on the elbow may be bad; it does happen I have seen it! This is one of those core principles that past failure and countless head scratching have taught. If you are using elbow test point indicators test the elbows hot before you switch. That way once you are parked and you have a de-energized indication you have a better presumption of which one of the three above you have. Always test before and after switching to ensure that what is supposed to be de-energized does and what is supposed to remain hot did. Too many times I watch people switch and move on to a new location and switch two more times before they realize something is not right and they often waste hours trying to figure out what is wrong when in reality the only problem may have been a mislabeled cable, inaccurate map, undocumented abnormal switching or previously someone else’s switching error. By checking what is hot and what is not before, during and after switching elbows will help you catch that problem immediately and will look like a hero and not a zero! Another tip is to verbalize that you are switching a single phase or all three phases, and when throwing gang operated switch gear please visually check that all three blades did fully open or close. This too saves a lot of running around later. Let’s assume now that all went well as planned with the switching and you or your designated switchman has properly de-energized the section of power line you wish to ground and work dead. Now, we can properly apply the equipotential technique, and trust it to work for us and not against us.

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