Grounds are NOT for your protection!

[500 KVA]

There's a thread on pet peaves on here. I was reading one that mentioned somewhere about placing grounds for your protection.

Do you realize that installing grounds on the line is NOT for your protection? It is for equipment protection only! Those cluster mounted grounds that you place on the primary on both sides of your work zone will not keep you alive, or uninjured if the line becomes energized. WILL NOT!

You are living under a false sense of security if you believe grounds will short that line out before the current gets to you. You will be injured or killed before that line trips out assuming that the settings at the reclosure or breaker are set and working properly.

The only thing that will keep you safe (Besides wearing your rubber gloves),is working within an equi-potential zone. personal protective grounds bonded onto the pole, or the basket you are working in. Rubber gloves from ground to ground. This is not to include hot sticks either!

It is just scarry thinking that some linemen place so much faith in an antiquated belief. I scare myself thinking back to the past when I believed that because that was what I was taught to do.

[Stick-it]

what do you mean when you say "this is not to include hot sticks either"

[500 KVA]

I mean working with hot sticks as rubber gloves, you are prtected and grounds are not a necessity. I said rubber gloves, then remembered some do work strictly with sticks.

[old lineman]

I beg to differ with you 500kva.
Here's the situation, we are building a parallel line EHV and the other line is energized at 345,000v. The length is 15 miles and getting longer every day.
Now this line has never be energized but it is deadly from induction.
Are you telling me that applying personal grounds at the structure is a useless effort?
In days gone by you would connect the grounds to the pole ground which is connected to the static wire which is connected to everything else that is metal and earthed as well.
Today I would install a pole band and include the pole in the schematic to create an equipotential zone, but to just wear rubber gloves day in and day and forgo grounds on a conductor loaded with induction would be foolish.
That's treating it as if it was alive and you can't do that.
They don't make rubber gloves for that voltage!
You better rethink what you said, because tomorrow somebody will be trying your idea and getting himself smoked.
The Old Lineman

[500 KVA]

You need to re-read! when I said grounding would not protect you, I was talking about the old theory of grounding. clusters at both ends of the work zone, and none at the pole being worked. I said personal grounds are a must. You need to create an equi-potential zone.

Grounds three structures to both sides of a working area, with no grounds at your sight is deadly. Please put your glasses on next time! I cannot figure out what in the hell you guys are looking at?

Nowhere did I say to wear rubber gloves to do transmission. If you think grounds are there for you, you are dead wrong! If you are using a pole band and doing an epz, then you are doing it correctly. Gloves will not hurt you if you fear induction. Maybe they are not rated for the potential voltage, but if there is nothing else available, you just going to use leathers?

[toptie]

Bullshit, the only danger from a grounding cluster, besides not being properly installed is them beating you to death if they become energized. And as a class A lineman you should know how to correctlly install them, and per newest rules by most companies, and I"m sure if thet OSHA regulatins by now but they require equipontentioal grounding with the tie to the system neutral and a well driven ground to eath as well.

[Sno10]

I am kind of confused with all this. This is what I know of grounds. If you want to put them up on structures on either side of you go ahead. It might help reduce the circulating current on a deenergized line. But you are not safe if you are not equopotential grounding at the structure being worked. If we are talking transmission here and on steel it is just a matter of grounding each position to the steel tower which gives the EPZ. On wood it will be by the use of your grounds and a pole band which go to a driven ground which is also bonded to a pole ground if present. Bond the worksite first then ground the line. Trucks that will be used for work should be bonded to your driven ground because it puts them at eqoipotenial with the conductor. By doing this though wether steel or wood you are protected on the pole, or tower you just created a hazard for the people on the ground. You just introduced a step and touch potential on the ground. Should be monitored so that it doesn't become to high with the use of a voltmeter, for your ground help's safety.
Your grounds should be also adequate to handle the fault current for the duration in cycles that your fault protection on the line takes to lock it out. Just because you have an equipotential zone with your grounding doesn't mean that your body is not going to see a voltage drop across it if you happen to touch the conductor and the steel you are a parrallel source to ground, if that line becomes energized or through induction. Your grounds should be sized to achieve your company's standards that comply with OSHA on the voltage and amperage seen by the body. Since most of the current goes with the path of least resistance the smaller the ground you put up the more current you will see across you. If your company's grounds are to small it may require multiple grounds on that structure to get the voltage drop across you down. Never tried to wear rubber gloves to eliminate nuisance shocks in transmission. I can see I would be drawing archs off every other part of my body that comes in contacts or close to any other steel. A good set of conductive boots or gloves takes care of that. Rubber gloves with a hot stick, No thankyou

[Stick-it]

If you are doing it correctly you should be safe when it comes to step and touch potential from your bonded trucks. It is not voltage that kills it is the amperage. If you have adequately sized grounds the amount of current that you will experience across or through your body will be minimal. If you use multiple grounds you need to remember that you have reduced the rating of each ground by 10%. I have read that studies have been done with dummies and voltmeters, and the dummie died every time they tried the touch potential test. That is except for when the trucks were bonded to the system neutral. Good luck on a wood transmission pole. Multiple ground rods?

[Linemo]

Those cluster grounds that you are referring to with a pole bail all create the equal potential zone that you are talking about 500 KVA and they together are for your protection not for equipment !

[500 KVA]

I am not talking about the personal (epz) grounds that are bonded to the pole as being for the equipment. can you read people?

Toptie is wrong. cluster grounds alone (not bonding onto a pole band) will get you killed. It is a false sense of security! Do you think that voltage will only travel down those grounds and not beyond them? No way it would get you huh? It follows the grounds as if they were directional arrows. HA!

This stuff was proven over and over by an engineer named Brian Erga who is creating the new osha standards now.

You are wrong about the path of least resistance. Electricity will take every path to ground. You think that you will be okay because you aren't the least resistant path to ground? You better wake up! You'll be the next to go if you don't educate yourselves!

Understand! You need to bond onto the pole! Grounding the old way by placing two sets of clusters a few spans to either side of you is wrong! In a transmission corridor this way will create an amperage along with the induction.

You don't even need to ground the personal grounds. They must be tied into every potential though, to include the nuetral and static if you will be going up to it.

Osha is minimum standards only, and very vague at that.

nobody said to hotstick with rubber gloves on. I didn't. When I was speaking of wearing rubber gloves, I was thinking more about working with a downed primary wire or a situation like that.

It amazes me how much your interpretation differs from what I am trying to say!

anymore I wonder if we are reading the same things?????

[Stick-it]

I have not misunderstood you 500. All I was trying to say is that if you can get the resistance of the ground down to near nothing then yes, you will still see a voltage drop across you. Being that the majority of the current will follow the path of the grounds the current drop will be miniscule across your body. That is for touch potential bonding and grounding only. As far as the pole band goes you are 100% correct.

[topgroove]

500KVA is 100% correct! The old way of grounding has been proven to be flawed.
For the last 80 or so years we have been taught to test dead and apply grounds on either side of your work zone... this will not save your life if the line becomes energized. current will still flow past your grounds and turn you into a 5K resistor. If your in your hooks on the pole the wood is about 20K resistance per foot of wood. You are a better path to ground then the pole your standing on. What 500KVA is trying to tell us is that the only way to ensure your personel safety is to create a equipotential zone. Its a fancy name that creates much confusion. The concept is real simple. You must create a work zone in which everything is at the same potential.
You must install a belly band around the pole just below your feet and have a set of grounds on each side of you no more than 6 feet away either side. I could post a ten page guide to equipotential grounding that I'm sure nobody would read but thats the nuts and bolts of the concept.

[Linemo]

Topgroove you are 100% correct if you look at my post this is also what I said !500KVA's post at first is not really easy to understand because it has so much in your face agression in it ! he is correct in what he said but you have to read and reread to get what he is trying to say!

[old lineman]

500KVA,
For some reason you think everyone has misread your post or they don't know what they are talking about. From the responses I see there are a lot of well informed individuals talking to you but I reread your post and have numerous problems with it. Whenever I write stuff I have to read and reread it making corrections several times, you should try that and fewer people would climb all over your frame, it works.
Look at the title---You say grounds are NOT for your protection! For whose protection are they George Bushes?
Grounds protect workers in many ways. I grant you they always protect to the max. possible when installed in the schematic of EPZ but they protect lineman. Have you ever heard of the term PERSONAL GROUNDS..
If you are about to work on a de-energized circuit, you first isloate, then potential test, then apply grounds.
We were always taught that this proves beyond a shadow of doubt that we had the right circuit.
There's a brand new post where a lineman was killed because he thought the circuit was NOT energized. Nobody took the time or made the effort to prove it. GROUNDS WOULD HAVE PROTECTED HIM. In this business everybopdy should be from Missouri--the show me state-- believe nothing what you hear and half what you see.
You and I agree bracket grounds (the old method) don't offer max. protection.
You say that grounds protect the equipment, excuse me! Where does that come from? If a line is out and the circuit is reclosed without grounds in place it's one heck of a lot easier on the equipment than if grounds had been applied. Applying grounds will likely blow something up but who cares about the equipment in this case. It's the workers who need protection.
'Hold off's' (blocked reclosers) are for equipment protection and not people. Indirectly it could help people because once the circuit is tripped the power won't come back. We NEVER conduct ourselves differently because a 'hold off' is in place.
Cover up as usual and wear all of your PPE.
You mention cluster mounted grounds. I hope you are referring to the cluster bar (pole band) on the pole. If you have done your home work then you don't install grounds in the cluster configuration.
Surely everyone has moved over to the cascade configuration. IEEE has been preaching this for years. On the other hand I'm not so sure because many contributors have also mentioned cluster grounds.
Some have talked about cable whipping. If you want cable whip use cluster grounding and then the magnetic coupling will take your head off. (Toptie said that, and he is right).
Most linemen think that equipotential grounding requires that the grounds be installed at the point of work. Not so.
If it is inconvenient to install grounds where the work is underway they can be installed at the next structure as long as a pole band is used in the proper fashion at the pole being worked. The max. distance IEEE permits is 300 feet.

[500 KVA]

You must be out of your mind.

Everyone knows grounds are for equipment protection. You are telling me that if you hang grounds on the line (without) attaching them to a pole band beneath you creating an epz, and the line becomes accidentally energized, you will be okay because the grounds will carry the electricity to the ground. path of least resistance???

You are a freaking fool!

The company does not want their super expensive breakers and transformers, and miles of wire serving all their customers, exposed to constant introduction of fault current. This will sooner or later destroy all of it wouldn't you say.

Do you even understand what fault current is, and what it does? Probably not from your statement.

Non-reclose(Hold-offs). How many cycles do you suppose travels through the line before the reclosure trips? 30 or so if operating properly, or even set correctly. I guess 30 cycles isn't 30 too many. How many will it take to kill someone? I'm asking you. Of course you probably think those 30 cycles never make it past the heads of that grounding cluster.

you better re-read your shit dip shit!

[Saline]

Hi Guys,

Well what can I say? This one's a rather hot topic. I think I will prefer the bare hander method where the EPZ is in the suit when working hot.

Grounds are for protection, the live’s of too many linemen having been lost because of a lack of understanding of the effects of grounding.

I have a tendency to believe that when everything is bonded to a single homogeneous mass, including the body of a person then it may be considered safe. Other than that complete isolation (Wearing rubber or stick work) is the safest.

[old lineman]

You must be out of your mind.

Everyone knows grounds are for equipment protection. You are telling me that if you hang grounds on the line (without) attaching them to a pole band beneath you creating an epz, and the line becomes accidentally energized, you will be okay because the grounds will carry the electricity to the ground. path of least resistance???

You are a freaking fool!

The company does not want their super expensive breakers and transformers, and miles of wire serving all their customers, exposed to constant introduction of fault current. This will sooner or later destroy all of it wouldn't you say.

Do you even understand what fault current is, and what it does? Probably not from your statement.

Non-reclose(Hold-offs). How many cycles do you suppose travels through the line before the reclosure trips? 30 or so if operating properly, or even set correctly. I guess 30 cycles isn't 30 too many. How many will it take to kill someone? I'm asking you. Of course you probably think those 30 cycles never make it past the heads of that grounding cluster.

you better re-read your shit dip shit!

Go back and read our two discussions. I have been discussing this subject without any curse words but you cannot control your language so I'll not discuss this with you further.
You sound like a little kid who can't get his way and just stands there stomping his feet.
Nothing will be gained here by you calling me names.
I know what I am talking about and you believe you do to.
The problem is two fold.
You don't know how to explain yourself well.
You can't hold a civil conversation, all you seem to know is how to cuss.
The Old Lineman

[HiLyne]

Don't know much about equipotential grounding but can any of you educate me on how the E.P.Z. works on grounding for personal protection on u.r.d. systems. Is grounding at the elbows sufficient?

[Radar]

Equal potential grounding, as a concept has been around since the mid 60's.

It was poo-pooed for nearly 30 years before it caught on...

Now everyone is on the epz bandwagon...dont get me wrong it's the best practice to create a epz...

but to make a blanket indictment that working between grounds is a "myth" without some specifices about how the grounds are installed is WRONG.

History shows that dozens of men have been saved with "obsolete" GROUNDING PRACTICES. A 1500+ohm man will always offer more resistance to ground than a grounding set with less than 1/2 ohm. ALL grounding schemes EPZ included use an element of time to hedge a bet in favor of your survival. Your body may drop whatever voltage gets past the grounds,,that's true... but a good short will trip the breaker or fuse in a timely manner ...that limits the TIME you may be exposed.

All a EPZ scheme does is keep you at the same (high) potential as the phase counductors while the short circuit takes the fuse out.

The secrect to placing 'bracket' grounding is to place the grounding sets as close to the work area as possible.... the greater the distance apart the grounds are the greater the circulaing current is between the grounds.

[Linemo]

Old Lineman you are correct in all of your statements about grounding and about 500 there is so much agression and anger in his posts not to mention the foul langauge that you really have a hard time following his posts !One thing is that he is consistant in that all his posts have the same tone and are very hard to read through !!

[500 KVA]

you guys are so sensitive. your linemen? cannot take harsh language? Wow I must be on some distant planet where linemen are sissies.

I am really laughing hard enough to piss my shorts at the moment. So sensitive.

My posts usually need a minimum of high school reading skills.

oops. i may have hurt your feelings again
HA!

[australiantroubleman]

Very interesting posts from many very experienced people.
I was taught years ago that grounds be they personal or worksite served three purposes all of which they said pertained to workplace safety.

1. To conduct to ground any induced voltages or currents, therefore making the worksite safe, be aware that faults on adjacent live equipment be it a parallel feed or device can induce very high up to 20 times more voltage or current into the worksite than would exist under normal conditions until a protection device operates.

2. To Protect from the effects of a failed isolation point the fault current produced should be suffient to allow protective devices to operate in as short a time as possible.This can be a very big problem on long feeds with high resistive/reactive limiting effects there may be only 30 amps availible under fault conditions in some areas.
In some areas we have to use "Known Grounds" (purpose built and tested grounding installations)only as a driven rod style electrode is worse than useless. In many cases at my company we have reclosers fitted near the end of long feeds that have only a 20 amp trip setting to cover this very problem and no work can occur past the recloser unless it is working and not bypassed.

3. We use large worksite grounds with bright yellow sticks to make them stand out be very visable new linemen are taught to always look for them as a means of proving their worksite is safewhere its possible.


This thread is very complex as touch potentials and fault currents,protection settings and adjacent live equipment all produce variables that make grounds not 100% reliable under all conditions at every time. But what is the answer i think that equipotential bondsl help to improve your chances the whole worksite rises in potential and hopefully you dont feel athing , but dont break the connections if parallel induced currents are flowing . Its a risk thing that we have to put up with in our jobs.

[PDSafety]

This is an important topic and not easily explained. It is harder to explain to lineman that stick or glove though. Bassically, if you know about bare hand work, it is exactly the same principles only backward.

500, I got your point the fist time and you are right. You almost had it 100%; if you would have said "the grounds are placed to 'opperate' the system protection" everyone would have understood you. They are not placed for the system protection, they are place to ensure that the system protection operates as fast as possible.
The whole point is to have someone understand what you are conveying, this is not a battle of whit, it is a forum for people to learn and share ideas... and there is a big difference between pen and tonge brother...that took me a long time to understand.

UG EPZ is more difficult and the only way to create it is with a grounding mat. Chance and Hastings makes great products as well as a few others.

Ground the elbows on either side and connect the mat to the concetric neutral on either side of the break. This allows the current on the conductor, the neutral and the mat to be at the same potential. There are big down falls to this though...Like, having your but touching the side of the hole or having your tool bag off the mat...everything has to be bonded to make it safe...it is difficult. If your working in a box pad, it is easier because there is more space around you and everything is easier to bond to a common ground. One other thing makes it a bit more tricky is getting into and out of the EPZ. You could do the HOP method and try to avoid any step potentials or you could use a rubber mat to access the equi-mat...at this point, it starts sounding like a load of crap and you might say something like, holly cow bat man, why dont we just spray ourselves down with an anti electic coating every morning...well, we are waiting for someone to make it...

Has anyone heard anything about the recent report from NEETRAC or the Study that AEP had done at Dolan Lab?

Both studies, independant without knowlege of the other say that the cluster bracket do not offer the protection as once thought. Pretty much, it does not keep the pole at close enough the same potential. I was told the only way to keep the pole at the same potential is to penetrate the pole into the heart-wood with the neutral bond. They said the best protection was a ground wire stapled to the pole and bonded to the system nuetral...

Any thoughts?

[wstxpwr]

What we have been told is that a ground wire stapled to the pole and bonded to the system neautral is bettet than the cluster bracket. The ground wire does not even need to be attached to the pole ground to offer better protection than the cluster. All it needs is to be stapled down the side. The staples need to get into the meat of the pole. The only problem I see with this though is the fact that 90% of the poles your going to be working on are going to be old and dry and probably stating to shell out. So the staples are going to need to be extra long to get to good wood. Any thoughts??? :confused:

[thrasher]

PDSafety:
I have heard for several years that a pole with a ground wire stapled down it and bonded to the neutral was as good as the cluster band but didn't know the source of the claim. Do you know where I can get a copy of the study you mentioned? Thanks

[Trampbag]

Excellent thread!

500KV is right, in essence. His statement about EPZ is spot on unfortunately he didn’t explain the safety grounds properly as PDSafety pointed out.

The application of cluster safety grounds, on 3 phase, or a singe safety ground on single phase ensures quicker trip time were the line become energised and is better when tied into a system neutral if it exists. This also drains the line of induction and static.

The use of a pole band, better with a bolt through the pole and tied into the band, placed below the feet of the linemen increases protection. On metallic structures the safety ground jumper should be attached below the work area.

Liken it to “bird on the wire”. In theory with EPZ in place with no safety grounds applied the linemen will survive should the line become energised. Safety grounds can be placed several structures away from the EPZ protected work area, because they do different jobs, and this makes it convenient where safety ground installation is difficult at the work structure.

Keep in mind that groundmen, or ground workers, working near the structure are exposed to increased risk because of step gradient if the touch the structure when EPZ is in place. This is particularly so if working metallic transmission structures in proximity to other energised lines. Voltage induced by miles of paralleling other energised lines can be very high and so the metal structure, if used as a point of attachment for the safety ground can have a lethal charge for ground workers. Even a driven ground rod used in conjunction with the EPZ may not adequately protect ground workers.

Also on URD the use of a grounding mat tied into the concentric or what the concentric is tied to will offer EPZ protection as long as the opposite end has the conductor attached to the concentric as well.

[WFO]

Trampbag

Your response was informative, well thought out, coherent and accurate. However, you neglected to curse, misspell anything, or challenge anyones manhood and/or legitimacy of birth.

Are you sure you're a lineman? :D

[PDSafety]

PDSafety:
I have heard for several years that a pole with a ground wire stapled down it and bonded to the neutral was as good as the cluster band but didn't know the source of the claim. Do you know where I can get a copy of the study you mentioned? Thanks

There are two recent studies. One by NEETRAC and the other by AEP. I heard AEP was going to publish in the IEE and to see the NEETRAC study...haahha, it will cost about $125,000. I know that Southern Company sponsered the study so if you know someone at Alabama or Georgia Power, they might help out.

I do know that all the companies that were involved with the studies have completley abandoned the use of the pole bracket.

I have gotten an invitation to AEP's Dolan Lab for first or middle of November, I should know more after meeting with them.

[HIVOLTS]

Grounds will save lives when applied properly. Source grounding, when doing construction work in an area like a substation will allow you to work any where in the zone where all potential sources have been grounded. Work site grounds, applied near your work are great if you are only working in that spot, like on a pole or changing a bus insulator in a sub. With work site grounds you only need apply one set, it doesn't mater which side you place them on. You will never prevent all of the current flowing through your body should what ever you are in contact with come hot, you are a conductor too,but if your grounds are in good shape, (Tested at least yearly) and installed properly than the amount of current flowing through you will be negligible. We use only 2/0 grounds,(minimum) and add sets where available fault currents are over 22.5ka. To say grounds wont save lives is reckless, and might influence others not to use them. To teach how to use them right is helping.

[Brian Erga]

We must not jump to early conclusions. Neither test has been published, nor has there been any peer reveiw for accracy and value by the industry. I had understood that AEP might present their test at the 2006 ESMO Show this month, but no one offered any information. I have seen copies of their powerpoint presentation without support documents, and I have a number of concerns and questions on how the test was preformed.

In our tests back in the late 80's we found the pole ground did help lower the voltage across the worker, but by only about 5%. We also found that a case grounded transformer helped lower the voltage across the worker by 5%. But by using the cluster bar we saw the voltage drop by a factor of 40 times to 8 volts. The cluster bar worked with, or without a pole ground and grounded transformer case. Now the pole ground and transformer does not hurt, but does not provide the level of protection that the cluster bar does. Also, you must make sure that the pole ground and transformer case is solidly bonded within the equipotential zone.

I understand AEP's point is that the staples holding the pole ground energizes the pole. However, many utilities us insulated pole ground wire and what happens when the pole ground and staples become loose? Studies I have found and read show current flows on the outside of a pole like it does with a conductor, making the cluster bar effective.

The NETRAC tests again have not been offered for peer review. I do understand that they used a system voltage of 480 volts. At 480 you will never break down a wooden pole. To do the test correctly you must use full system voltage.

One significant test that was recently conducted by the Bureau of Reclamation, and is published, found that the electromagnetic field around the grounding jumper, and the current loop developed by the worker on the conductor, can increase the voltage by a factor of 3. This information supports the increase in voltage and current across the worker in our tests by a factor of two when we installed grounds on both sides of the work area. This test tells us that we need to have the voltage drop across the grounding jumper at no more than 20 to 25 volts.

They also found when doing full tests at 230kV on a two pole wood structure, the cluster bar lowered the voltage across the worker by a factor of 4,000. The cluster bar worked very well and provided complete worker protection on a wood pole at 230 kV. Without the cluster bar the worker would not have survived. The Burau's tests can be found at www.usbr.gov.

Due to the concern in AEP's and NETRAC's recent tests, the IBEW is trying to put together a meeting of IBEW, EEI, IEEE, AEP, and NETRAC, ASAP.



There are two recent studies. One by NEETRAC and the other by AEP. I heard AEP was going to publish in the IEE and to see the NEETRAC study...haahha, it will cost about $125,000. I know that Southern Company sponsered the study so if you know someone at Alabama or Georgia Power, they might help out.

I do know that all the companies that were involved with the studies have completley abandoned the use of the pole bracket.

I have gotten an invitation to AEP's Dolan Lab for first or middle of November, I should know more after meeting with them.

[Brian Erga]

Good Points!

I am glad you brought up grounding in the underground. OSHA 1010.269 (n)(3) states you must create an EPZ. This includes overhead distribution and transmission, substations, networks and the underground! SDG&E tests show that EPZ grounding is just a valuable, if not more, in the underground as in the overhead. After assisting with these tests I was asked to chair an IEEE/ESMO work group assigned the task of publishing a paper on worker protection in UG systems. The paper provides three options: Insulation, Isolation, or EPZ. During my testimony to Federal OSHA in March 2006 on the revision OSHA 1910.269 and 1926 Subpart V hearings, I submitted the UG procedures for inclusion in the revision. We will see what happens.


Excellent thread!

500KV is right, in essence. His statement about EPZ is spot on unfortunately he didn’t explain the safety grounds properly as PDSafety pointed out.

The application of cluster safety grounds, on 3 phase, or a singe safety ground on single phase ensures quicker trip time were the line become energised and is better when tied into a system neutral if it exists. This also drains the line of induction and static.

The use of a pole band, better with a bolt through the pole and tied into the band, placed below the feet of the linemen increases protection. On metallic structures the safety ground jumper should be attached below the work area.

Liken it to “bird on the wire”. In theory with EPZ in place with no safety grounds applied the linemen will survive should the line become energised. Safety grounds can be placed several structures away from the EPZ protected work area, because they do different jobs, and this makes it convenient where safety ground installation is difficult at the work structure.

Keep in mind that groundmen, or ground workers, working near the structure are exposed to increased risk because of step gradient if the touch the structure when EPZ is in place. This is particularly so if working metallic transmission structures in proximity to other energised lines. Voltage induced by miles of paralleling other energised lines can be very high and so the metal structure, if used as a point of attachment for the safety ground can have a lethal charge for ground workers. Even a driven ground rod used in conjunction with the EPZ may not adequately protect ground workers.

Also on URD the use of a grounding mat tied into the concentric or what the concentric is tied to will offer EPZ protection as long as the opposite end has the conductor attached to the concentric as well.

[PK270]

I understand EPZ as it pertains to overhead, how does this apply to underground?? Or should I say how do you create an EPZ in underground TX's ?

[Trampbag]

Isolate cable at both ends.

At the end away from work site use a feed thru and grounding elbow. Attach duck bill or connector on vault, JB or transformer grounding grid or bracket where concentric is tied. In this case it doesn’t matter if Wye or Delta system, all high voltage cable is constructed with a concentric of some type. On new cable strip exposing conductor and concentric, use temporary connector and attach conductor and concentric together and to ground grid. If working on two or more cables make sure all concentric and conductor is tied together onto the ground grid at end opposite to worksite.

At work site connect lead from “grounding mat” to ground grid where the concentric is attached and stand on ground mat while touching the conductor.

Be careful to keep both feet on grounding mat. If there is a possibility of touching equipment or anything not tied into the ground grid insulate it from yourself with a blanket.

[Brian Erga]

NO, this is a very DEADLY work method. If the pole ground is not attached to the system neutral, grounds are installed between the conductor(s) and the neutral, a cluster bar is NOT used, and you are in contact with a grounded line when it becomes enerized, you will have as much as full system voltage across your body, at the very best you will 1/2 of the system voltage (on a 7200 volt line that is 3,600 volts).

Again, there is no indurstry accepted test that shows any procedure provides more protection that the EPZ work method. And Federal OSHA requires the use of the EPZ work method in 1910.269 (n)(3).

As I have said in other notes the EPZ work method provides complete protection if installed properly, the pole ground tied to the system neutral helps but does not provide any protection on its own.



What we have been told is that a ground wire stapled to the pole and bonded to the system neautral is bettet than the cluster bracket. The ground wire does not even need to be attached to the pole ground to offer better protection than the cluster. All it needs is to be stapled down the side. The staples need to get into the meat of the pole. The only problem I see with this though is the fact that 90% of the poles your going to be working on are going to be old and dry and probably stating to shell out. So the staples are going to need to be extra long to get to good wood. Any thoughts??? :confused:

[Brian Erga]

Information on grounding can be found in IEEE 1048, OSHA 1910.269(n)3, the Bureau of Reclamation "Personal Protective Grounding Standard."
and our IEEE paper "Test Results of Personal Protective Grounding on Distribution Line Wood Pole Construction," to name just a few. I will try to put this paper and our truck grounding paper on our website by Nov. 10, 2006. The web address is www.esci.net



PDSafety:
I have heard for several years that a pole with a ground wire stapled down it and bonded to the neutral was as good as the cluster band but didn't know the source of the claim. Do you know where I can get a copy of the study you mentioned? Thanks

[Trampbag]

NO, this is a very DEADLY work method. If the pole ground is not attached to the system neutral, grounds are installed between the conductor(s) and the neutral, a cluster bar is NOT used, and you are in contact with a grounded line when it becomes enerized, you will have as much as full system voltage across your body, at the very best you will 1/2 of the system voltage (on a 7200 volt line that is 3,600 volts).



You give no explanation how a how a lineman can get involved in series or half series?? How did you get 1/2 voltage?? Where did I say to tie into a transformer or coil? What the hell is a cluster bar?

This is the problem in the industry. Safety people, not qualified electrical linemen, writing trade safety regulations that can bite us in the ....

However, considering that your advertisement indicates that you are a lineman, and if you want to speak as an industry voice consider using terminology a little more professional especially where the line trade industry is so well represented. You’ll gain some respect, maybe.

Any voltage is going to travel both the conductor and the concentric when tied together. The other suggested method of EPZ is to remove the concentric from the ground grid and tie the concentric and conductor together at the end away from the work using the ground mat at the work site.

The Europeans make switchgear that isolates and then can ground, with use of lockout keys, at all terminations points. By grounding away from the work end, which ties the concentric to the conductor, an EPZ zone can be made at the work end by attaching an earthing mat to the equipment. I can’t for the life of me recall the name of the manufacture, I think it was German or Swiss, but it seemed to me quite a common idea on switch gear.

[linemanfrog]

I have heard that putting bracket grounds....where you ground all the conductors including neutral together on both sides of your work area will produce a circulating current. Yet when you install your personal protective ground (ie. EPZ, equipotential ground, ground chain, etc.) on the pole you are working that it eliminates the circulating currents.

I am no engineer or professor of electronics but I think that a properly grounded line should include.
1. Grounds installed within 3 spans on each side of your work area.
2. Grounds installed at the structure you are working on to include a ground cluster around the pole (pole band or whatever you want to call it).
3. All lockout tag out procedures in place. (Tags on switches, grounds, and relays).

In reality you should always remember that you are trusting your life to man made products. Whenever possible I do not trust any electronic or oil switch.

Open
Check Open
Tag
Test
Ground

And always make a visual open whenever possible. Remove jumpers, lift the top side of disconnects, or anything else that helps eliminate the possibility of an accidental reenergizing of the line you are working on. I do not trust relays and circuit breakers.....theres only a very small distance between the contacts of a relay in a substation.....

When in doubt wear your gloves. I know you cant wear them on transmission. You should take the extra step to isolate yourself whenever possible. Just because you have grounds on a line does not mean you have to lay all over it, have one hand on the line and the other on the pole, or in any other way take unneeded risks. Regardless of your beliefs in grounding, at the very least follow your companies policies so your ass is protected if you do get hurt. There is nothing saying you cant exceed your companies policies but you better be at least meeting them or you wont have a leg to stand on if you get hurt now days.

[mscheuerer]

This stuff was proven over and over by an engineer named Brian Erga who is creating the new osha standards now.

Tramp, the way i'm reading it is that this is the same "Brian Erga" that 500 Kva was talking about a few posts back...

[Trampbag]

Ditto on the “I’m no engineer” as well. Perhaps one will correct me.

I have experienced what I was told was circulating current. When working transmission maintenance isolated and grounded and where the line is paralleling miles of other transmission lines. My experience and understanding is that if you are working at the ¼ (or ¾) point the circulating current is at its worst. Say 100 miles of line, 500kV, is isolated with at air switches at either end and work is performed at 25 miles from the one open switch and there are 2 other 500 kV and a couple of 230kV lines are paralleling. Some companies lift grounds at the switches some do not trying to deal with circulating current. However my experience is that regardless the ¼ point will draw the largest arc when removing working safety grounds and if you clamp amp read those working safety grounds the readings will be at their highest. I’m told that the longer section distance has much more voltage and current and opposes the lighter loaded shorter section. I have experienced arcs of 10’ to 15’ when lifting working safety grounds at the ¼ point yet had very little at or near the ½ point on the same line.

I understand that on transmission cable the reason the grounds are not connected hole to hole to hole, but rather there is a gap in ground at the splice is to eliminate circulating current damage should the ground get severed.

I have not experienced circulating current on distribution U/G possibly because the long distances are not involved and the voltage is substantially lower. I would think circulating currents in U/G distribution would not be considered a large problem. I have never been warned of it while working such systems.

This is drawn from my experience and I have no calculations to back this up. Can someone out there explain this phenomenon with calculations?? I have search the net but can find nothing on circulation current outside of it being classed as a super coil causing high currents.

[mscheuerer]

LF; It almost appears to me that in similarity we're talking about "Eddy Currents". (i.e. An electric current induced within the body of a conductor when that conductor either moves through a nonuniform magnetic field or is in a an area where there is a change in magnetic flux) thus causing circulation currents (as your talking about) to be emanated and picked up by other conductors found intersecting or running parallel (EVEN GROUNDED ONES) to transmission lines.

Sometimes dependant upon weather conditions (wind, humidity etc...) and the type of voltages/currents addressed, these "eddy" currents can be lethal to us as well if we're not careful. A bonafide EPZ is a good way to go (And i'm talking MULTIPLE circuits, not just a one lonely pole gig) but I would have to figure my ground placement and distancing to be a determining factor. Thatsa what we learned in "electric 101." Now i'm no ENGINEER either but we work this stuff everyday. These currents are very well known to be found in the static wires atop transmission circuits and when removing our clamps (on a fuzzy day) can sometimes cause an arc (if your lucky).

Tramp; try your search on this particular phenomenom (also called a Foucault Current) and see if it is what your looking for.

Hope this helps.

[Trampbag]

After 2 hours of searching every thing I can think of I am still no wiser as to exactly what I have experienced. Even a lengthy search in Transmission & Distribution Magazine on line produced very few answers.

I do know, however, it has cost a number of linemans lives when they get caught up in the situation I am talking about. North Scotland Hydro’s Head of Safety gave me some literature on their concept of what was happening and he said he considered working on isolated grounded transmission lines the most hazardous work condition in their system. I know I would rather work 230kV (on towers) and 500kV using live line methods than grounded (systems in service, not construction). There are just too many variables in potential hazards for both workers aloft and on the ground.

Hopefully some one can explain adequately what I have experienced.

[Trampbag]

What ever I experienced, circulating current, eddy current, Foucault current or other current, articles in T&D magazine and a few others I can find all seem to indicate that Equal Potential Zone grounding (EPZ) will protect the workers aloft from electrocution. I would imagine EPZ grounding in conjunction with safety working grounds are the best way to protect linemen from injury while working.

While working in California I heard little of EPZ. New Jersey and Connecticut seemed to require it but it was optional (please correct me if I’m wrong) Ontario, Canada required EPZ for equipment like pullers and wire carriers and tensioners. Other places were anywhere between.

What is going on in your location???

[spur]

Holy Crap what a hot topic!!!!!
We at our little utlitly have adapted to the equipotential grounding in the past few years at first I didnt put any faith in it I thought [wrongly that bracket grounding was safe] But on any transmission system out there if you ground in the traditional sense at one end of the line and then bond with a cluster bracket on the pole you are working on [all potential energized objects] you will not recieve any pick up if your feet are above the protection zone. Soo if you dont get any pick up [induction from other lines] and you did before there must be something working right.
:) SPUR