1/19/06
Question:

When working on de-energized transmission lines with a bucket truck, and the proper PPG is placed on the lines with the truck grounded, should an additional PPG conductor be attached from the truck's bucket to the line (to essentially jump around the man in the bucket)?

What is the recommended practice under this situation when using either an insulated boom truck or a non-insulated boom truck?

My impression would be that the bucket would not have to be grounded when using an insulated boom, since the insulation of the boom would prevent current flow through the worker in the bucket in the event that the line becomes energized, however the added ground will not hurt.

However, when the truck is non-insulated, a ground would be helpful to protect the worker in the bucket in the event the line was energized, essentially the jumper from the line to the bucket would assure that the bucket is at the same potential as the line. What are your thoughts? Thanks.

Thanks for your question.

If you are using an insulated bucket truck, insulated for the voltage involved, and you have developed an equipotential zone (EPZ) at the worksite, you do not need to ground the bucket itself. I would recommend that the chassis be grounded to the best available ground source.

If you are using an un-insulated bucket truck and you have developed an EPZ at the worksite, you must install a jumper between the bucket and the conductor being worked. I would again recommend that the chassis also be grounded to the best available ground source.

Brian Erga, President, ESCI Inc.

10/19/05
Question:

Attached is a drawing of a question that was brought up about the possibilities of circulating current on 115kv lines when installing personal grounds when you have another 115kv line running parallel and then crossing over the line you're working on.

These are both 115kv lines with line B running parallel and then across line A. The question came up about the possibility of circulating current between the main line switch and the other sets of individual grounds installed at the other two work points. A lineman's field manual indicated that there is the possibility of circulating current with this type of setup. I felt it might be possible in extremely wet terrain, but this is Okanogan, and it is bone dry and rocky terrain which should not create such a hazard. Any help on this question.

Great question,

There is probably not a great change of circulating current since the lines parallel for only a mile. But, I have learned to never say never when it comes to circulating current. The distance between Line A and Line B, and the current being carried in Line B will impact the circulating current in Line A. If Line A and Line B are within the same corridor and B is carrying 500 plus amps there could very possibly be circulating current due to the grounding procedure being used on Line A.

A simple solution to this problem is to open the ground switch(s) on Line A. The ground switches provide no protection for workers working on Line A. The crew should then only ground at one location (the work site) with EPZ. Grounding on either side of Line B crossing again provides no worker protection.

The best protection and simplest process is to ground at each work location using the equipotential grounding method and ground no where else.

There was an interesting accident in California recently where a transmission line had been de-energized, the ground switch at the station had been closed, grounds installed at the work site, and the station breaker closed accidentally. After the accident they re-enacted the accident and measured 9,000 Amps at the work location with the ground switch closed at the sub. So much of ground switches.

Brian Erga, President, ESCI Inc.

06/04
Question:

On an existing 13.2 line: they are taping off the existing line to a new line. The new primary and new neutral are both caught off on insulating hoists with a fiberglass extension stick. Both tails are tied back and taped. Can they work this extension with leather gloves or is single point required?

A: Great Question! Yes, this is a perfect example where grounding is not required. Now, I am assuming that the new line does not have any change of backfeed from transformers connected to homes or businesses. Gloves are all that is needed in this case except the usual PPE.

Brian Erga

3/11/03
Question:

A 7200 V single-phase conductor and neutral, between pole four and pole five, has been broken mid-span by a tree and both conductors are lying on the ground. The crew has installed a set of working grounds between pole three and pole four, and a set of working grounds between pole five and pole six (working grounds are properly sized grounding cables and grounding clamps installed between the neutral and phase conductor(s).) Equipotential grounding practices have not been used (a cluster bar and a grounding jumper from the cluster bar to the neutral installed on both poles ) on this job. A bucket truck will be used to raise the conductors into place and spliced back together. Can the crew safely, and legally, re-install the conductors using only working grounds and wearing Class 2 rubber gloves?

A: Yes! This is an acceptable way to install conductors broken mid-span. In fact, equipotential grounding only protects workers positioned on the same pole as the equipotential zone. Workers not located on this pole have no protection unless they wear rubber gloves rated for the system's voltage. When workers are not in this equipotential zone of protection, rubber gloves rated for the system's voltage are one way to protect themselves when contacting phase or neutral conductors.

The other method of protecting workers contacting downed lines is by installing grounding jumpers on either side of the break and installing an equipotential grounding mat at the location where the workers will be standing and contacting the conductors. This equipotential grounding mat must be installed to the conductors on both sides of the break.

Equipotential grounding provides protection only for workers positioned within the equipotential zone. The equipotential zone is developed by installing a cluster bar below the working position, a grounding jumper is installed between the cluster bar and neutral and grounding jumpers installed between the neutral and phase conductor(s).

Federal OSHA 1910.269(n)(3) and ALL state laws require the use of equipotential grounding methods on de-energized lines and devices, or workers must insulate or isolate themselves from the conductors and devices. If workers choose to use the rubber gloving method in states having a 5000 V, maximum, rubber gloving rule, workers must first install grounding jumpers between the phase and neutral on the conductors to be worked. Remember, however, if you choose to NOT use the equipotential grounding method, but simply the grounding jumpers and the gloving method, you must fully comply with ALL rubber gloving work methods and practices when conducting this work.

We hear comments from workers who say "The grounds are a pain," or "Grounds always get in the way," or "If the line is tagged and grounded on both sides, we are safe." Try telling that to the 50 plus United States journeymen linemen who died in 2002 when they also thought grounds were a pain, or they get in the way, or grounds on both sides are enough. The equipotential law is there for a reason, IT SAVES LIVES.

2/21/03
Question:

At a PUD's general safety meeting recently, we heard a question asked about the new DOT laws that have been pulled back a little. You know, the ones where two tickets for illegal lane change, tailgating, etc., would result in loss of CDL for 60 days, etc. The guy who asked didn't understand that the employee's responsibility to report all traffic convictions was not affected by the proposed law.

A: Some people want to look for a loophole because they feel like their privacy is being invaded.

I want to clarify about having to report moving violations to the PUD. The Federal Motor Carrier Safety Regulations, Subpart C, Paragraph 383.31 explains the reporting procedure for motor vehicle violations. It requires CDL drivers to report within 30 days any violations other than parking tickets to their employer. It doesn't matter if the violation happened in the state where you have your license or not.

At the time I said it was PUD policy, but the more I thought about it, the more I remembered that there was a regulation that addresses it.

Stephen P. Frost, Director of Field Operations, ESCI

2/12/03
Question:

What portion of an extendo stick can I consider insulated? Can I assume the entire stick will insulate from energized lines?

Telescoping (Extendo) stick testing and protection. Extendo sticks are tested from the factory for the entire length of the stick, but once they are put into service, the hollow sections of the stick may become contaminated and the only advertised protection from the stick is in the last foam-filled section of the stick. The stick must be not be used as a hot tool below the foam-filled section. The stick needs to be cared for in the same way we care for all sticks, i.e., it needs to be wiped and inspected before using, especially the foam-filled section. When you do in-service testing, the foam-filled section of the stick must pass. Even if you clean the outsides of the hollow sections, there is no guarantee that the impurities inside these sections will not track.

As with all hot tools, don't use extendo sticks beyond their electrical and mechanical capacities.

5/28/02
Question:

I am a Safety and Training Instructor with the Virginia Association of Electrical Co-ops. I have two important questions that I feel you might be able to help me with.

1. On an overhead distribution system is there another means to get equalpotential other than using the bale system.

2. Does using the pole ground on the co-ops system comply, that is with a pole ground on every pole and staples driven every six inches and the pole ground meggered at 25 ohms.

These two questions were brought to my attention at Northern Virginia Electric Co-op in Northern VA. My training came from Virginia Power where we used the bale. Please advise, George R.McRae, Safety and Training Instructor VMDAEC

1. Yes, what we call the cluster bar or chain binder, is the only way to assure that you have an equipotential built for the workers. The reason is that current will run on the outside of a pole just like it does on a conductor. Why, because the majority of the moisture (rain water) and treatment (penta, creosote, copper napanate) are on the outer 1" of the pole. Connecting the conductors to the neutral and then to the cluster bar will energize the outer portion of the entire pole. Some ask if a thru-bolt will do the same thing, yes, maybe but I would not count on it and it is not really a grounding device (the bolt) the 5/8" or 3/4" bolt with a 2" flat washer contacts a very small surface area of the pole. The cluster bar (chain binder) is the only accepted device that I know of.

2. The pole ground wire does help somewhat. In my studies in the 1980s I found that the pole ground when stretched tight and in full contact with the pole helped somewhat. However, when we added the cluster bar we got a substantial reduction in voltage across the worker. As the pole is in the ground the pole ground gets loose and does not make good contact with the pole as the pole dries out and shrinks. Also, what if the pole ground gets broken or has a loose connection at the neutral.

Great questions. Thanks, Brian

6/1/01
Question:
If you're working a de-energized 230 kV transmission line, two miles from the substation, using the equipotential grounding procedure (jumpering the three phases to a cluster bar and developing an equipotential zone), how do you protect workers on the ground from step and touch potentials?

You should keep workers on the ground a minimum of 15 feet from the bottom of the structure and any driven ground rod. The use of insulated footwear is also something you might what to consider for everyone on the ground.

The use of equipotential grounding does not increase the danger for workers on the ground when compared with the old system of grounding. The hazard has always been there for ground workers and continues using equipotential grounding. In the old grounding system workers jumpered the phase conductors together, then jumpered to a static, or a temporarily driven ground rod. In using the static the structure may have a pole ground which becomes part of the grounding system and creates step and touch potentials. The use of a temporary ground rod also allowed fault current to be "dumped" into the ground near workers on the ground.

Step potential is developed when fault current enters earth at the ground level of a structure, pole, or ground rod. The fault current traveling into the earth at that point wants to travel back to the generating source and will take many paths. The fault current dissipates in all directions from the structure, pole, or ground rod and becomes less intense as it is able to dissipate in all directions from the structure, pole, or ground rod. Very near the structure, pole, or ground rod the current is high and the fault current traveling through earth, times the resistance of earth, develops step potential. When a worker is standing a distance away (15 feet or more) from the structure, pole, or ground rod, the fault current is able to dissipate greatly and the current at that point, times the resistance of earth, will develop lower step potential compared with the step potential very near the structure, pole, or ground rod.

Is the magic number 15 feet? No. I depends on the fault current and resistance of earth at the work location. Many utilities use 15 feet or more for transmission voltages depending on their system design and operating methods.

If the structure is steel, the tower will be tied into the equipotential zone. The base of the tower and the footing grounds can develop high step and touch potentials. Workers should remain a distance away for the base of the tower. If the structure is wood, the pole(s) will also be tied into the equipotential zone. The pole will also create step and touch potential hazards for the workers due to pole grounds and the conductivity of the pole. If a ground rod is used to ground the line, it should be installed a distance from the base of the pole or structure, and away from workers on the ground. Studies have shown that installing the ground rod a span away from the work location may lower step potentials in some cases.

5/15/01
Question:
If a qualified operator is operating a highway digger with a steel mast and they do not ground the truck, do the overhead lines need to be covered? How close can the truck be operated to the overhead lines?

OSHA 1910.269 (p) Mechanical Equipment, requires that when any mechanical equipment (highway digger) is operated near energized lines the operator must do one or more of the following:

1. The energized line shall be cover with protective materials (cover-up), or
2. The mechanical equipment shall be insulated for the voltage involved. The mechanical equipment must be positioned so that the un-insulated portion of the mechanical equipment cannot contact the energized line, or
3. The mechanical equipment shall be grounded to the best available ground, and

a. All equipment shall be bonded together, and
b. Ground mats shall be used, and
c. Insulating protective equipment or barricades shall be used.

Now what does this all mean in relation to your question? A highway digger does not have an insulated portion of the boom so option 2 is out. The line can be covered as stated in option 1. Enough cover-up must be installed so that the boom of the highway digger cannot get within the minimum approach distance (MAD) of the energized line.

Your second question: how close can the boom get to an energized line? Section P states that protection must be taken if the boom could contact the energized line. You did not give me the voltage of the line, so I will assume we are talking about a system below 50 kV. Some type of protection shall be used when the boom is operated within the distances of OSHA 1926.550(a)(15), the 10-foot rule.

Now Section P is all messed up. It states that if you ground you must also use ground mats, and insulated protective equipment, or barricades. It should read if you ground you must use ground mats, or insulated protective equipment, or barricades. ESCI is working with Mr. Dave Wallis, Federal OSHA, to fix this section as part of the revision of OSHA 1926.

To answer your question if you do not want to ground, and a highway digger does not have an insulated boom section, the only option you have is the use of insulated cover-up whenever the highway digger is operated within 10 feet of a 12 kV energized overhead line.

4/30/01
Question:
Do I need to ground my insulated bucket truck when working near energized lines and equipment?

OSHA 1910.269 (p) Mechanical Equipment states "Mechanical equipment shall be operated so that the minimum approach distance of Table R-6 through R-10 are maintained from exposed energized lines and equipment. However, the insulated portion of an aerial lift operated by a qualified worker in the lift is exempt form this requirement."

This paragraph means that if your bucket truck is insulated, tested for the voltage involved, and operated by a qualified worker in the bucket, you do not need to ground, barricade, or take any other steps to protect workers on the ground. However, you must ensure that the un-insulated portion of the truck does not get within the minimum approach distance (MAD). You can position the insulated boom up to, but not touching, the exposed lines or equipment. Also remember the qualified worker in the bucket cannot enter MAD (the minimum approach distance) unless insulated protective equipment is used.

Now that's the law, if your utility requires you to ground the bucket truck this could add extra protection for workers on the ground. In all the years I have been involved with grounding, I have never heard of anyone killed or hurt around a properly grounded truck.

4/18/01 Question:
If I am going to ground my truck, what do I ground it to? Do I need to take additional steps besides just grounding?

Tests conducted at the A.B. Chance Labs, and published in IEEE 91 SM 312-9 PWRD, showed the best protection for workers on the ground, around trucks, occurred when the truck was grounded to the neutral. Grounding the truck to a driven ground rod provided no protection. The eight-foot ground rod was driven in to undisturbed soil a full eight feet and the ground resistance was measured to be 18 ohms.

3/24/01
Question:
When do hot sticks need to be tested?

( j ) (2) (ii) If any defects or contamination that could adversely affect the insulating qualities or mechanical integrity of the live-line tool is present after wiping, the tool shall be removed from service and examined and tested according to paragraph ( j ) (2) (iii) of this section before being returned to service.

29CFR1910.269 ( j ) (2) (iii) Live-line tools used for primary protection shall be removed from service every two years and whenever required under paragraph ( j ) (2) (ii) of this section for examination, cleaning, repair, and testing as follows:

( j )(2) (iii) (A) Each tool shall be thoughly examined for defects

( j ) (2) (iii) (B) If a defect or contamination that could adversely affect the insulating qualities or mechanical intergrity of the live-line tool is found, the tool shall be repaired and refinished or shall permanently removed from service. If no such defect or cintamination is found, the tool shall be cleaned and waxed.

Most utilities in the Northwest have their live-line tools inspected and tested within the two year period. ESCI advocates this practice which is more stringent than the regulation.

Remember the live-line tools need to be removed from service every two years and must be inspected. In order to verify this inspection the individual tools need to be identified (marked) in some manner.