Trees in the Line

[Figurehead]

How are you removing trees from the line? Hot? Gloves and a chainsaw? De-energized and grounded?

I ask because good judgement comes from bad experience and I had one. Took a jolt from a branch while cutting a tree out of hot 7.2 kv with gloves on. The branch rolled and contacted my shoulder. We cut alot of trees out of lines and it's our call how to take em. Personally I'm real good with a saw and haven't met a tree yet more savvy than me. Point is- Alaska is a 5kv glove state. Beyond that it's sticks. Even so, in the field we opt to glove up and saw trees out of hot lines. I'm the third hand I know of to recently get hit with primary from a "hot" tree.

Many of our tap fuses are a real bugger to get to and are not loadbreak cutouts. We can hump tools and a loadbuster, climb and dump hundreds if not thousands of customers for an hour... or glove up and cut.

So- how's it done where you are?

[mainline]

If we have a tree on an energized primary that we have to ground cut we open the line, test , tag, and ground it, then remove the tree. If we can get to it with a bucket we can work it hot and cut it clear using a Hastings hydraulic stick saw. If you guys don't have them try to get one as a test. They are one of the best tools you can have in a storm. They let you get some clearance from what you are cutting. The grounding can be a pain, but it keeps you safe, if you have big extendo sticks you can put grounds on from the ground. It saves you having to lug all of your rigging in just to clear a tree. I think if a safety guy caught me cutting stuff off hot from the ground gloves or no gloves I would probably get some time off. Stay safe, Mainline

[Meat]

How are you removing trees from the line? Hot? Gloves and a chainsaw? De-energized and grounded?

I ask because good judgement comes from bad experience and I had one. Took a jolt from a branch while cutting a tree out of hot 7.2 kv with gloves on. The branch rolled and contacted my shoulder. We cut alot of trees out of lines and it's our call how to take em. Personally I'm real good with a saw and haven't met a tree yet more savvy than me. Point is- Alaska is a 5kv glove state. Beyond that it's sticks. Even so, in the field we opt to glove up and saw trees out of hot lines. I'm the third hand I know of to recently get hit with primary from a "hot" tree.

Many of our tap fuses are a real bugger to get to and are not loadbreak cutouts. We can hump tools and a loadbuster, climb and dump hundreds if not thousands of customers for an hour... or glove up and cut.

So- how's it done where you are?From the ground? Un****ingbelievable! Are you serious? Open it up and ground it or you're gonna die!

[Meat]

I may have jumped the gun a little last night. Not sure if I'm clear how you're removing the trees. A chainsaw with rubber gloves trimming a tree out of an energized line seems crazy. From a bucket or anytime. I've always said tree removal is the most dangerous thing I've done. They are unpredictable even to experienced lineman. Your post suggests you are breaking safety rules and had 3 close calls. I would suggest you do the right thing from now on. (refer to Mainlines post) I could go on further about removing the weight off the line, tagging the phase off to a truck, tons to discuss on this subject. Done for now,Meat!

[billg]

Yesterday I was driving down a back road near home and found a guy about to tie a white rag onto a limb that was hanging down into the roadway, suspended a few feet off the ground. The scary thing was that the limb was hanging on a 7200 volt line. I really had to talk this dude out of what he was trying to do. He was intent on warning other drivers. The general public has no clue. If I was a minute or two later I would probably have found this guy laying in the road.

[mx-5]

call for a tree crew...;)

[Figurehead]

Happy Fathers Day, Just got back from camping and fishing with my daughters and friends. Longest day of the year, it's midnight and still very light out. Really enjoyed a break from daily life at home.

Trees- In the line hot and burning, glove up and cut them out from the ground. I did that for a long time. Then I took a hit from who knows what voltage, it hurt.

I was on call last weekend and took probably half dozen trees out of the line. All the trees I took were on lines I opened and grounded. I, we, lineman here, are the tree crew for trees in the line. A couple times a week we're removing trees from hot lines and this happens on multiple crews.

I'm bucking the trend here in my local and at my utility and hear, " it's always been done this way, this is how we do it". It comes down to the same arguments of humans being lazy and us being our own worst enemy. Anyway- The right thing to do and I've known it since day one is to open and ground then remove the tree.

So far I'm the only hand to insist on this. The utility's going to notice the change to outage response/restoration time and the older hands are going to resist it. I just can't see the reason to continue cutting trees from hot lines. Our safety should be first.

[CPOPE]

Stick to your gut instinct - cutting a tree from grade - hung up into an energized primary is a bit cowboy. Even if you are clear from grade in an insulated bucket cutting the tree clear while hung up in primary conductor that is energized comes with a boatload of risks.

Not saying it can not be done safely but you have to know and understand the risks. Should your Utility have an accident the JHA better be in place. I do believe as you've described and if you do a Job Hazard Analysis on the task you'll come to agreement with the other hands on the best way to approach each individual situation.

http://www.osha.gov/Publications/osha3071.pdf

With Dielectric Footwear and Gloves the electrical hazzards of step and touch are covered. That said work it dead.
Appendix C to §1910.269 -- Protection From Step and Touch Potentials
I. Introduction

When a ground fault occurs on a power line, voltage is impressed on the "grounded" object faulting the line. The voltage to which this object rises depends largely on the voltage on the line, on the impedance of the faulted conductor, and on the impedance to "true," or "absolute," ground represented by the object. If the object causing the fault represents a relatively large impedance, the voltage impressed on it is essentially the phase-to-ground system voltage. However, even faults to well grounded transmission towers or substation structures can result in hazardous voltages.(1) The degree of the hazard depends upon the magnitude of the fault current and the time of exposure.

II. Voltage-Gradient Distribution

A. Voltage-Gradient Distribution Curve

The dissipation of voltage from a grounding electrode (or from the grounded end of an energized grounded object) is called the ground potential gradient. Voltage drops associated with this dissipation of voltage are called ground potentials. Figure 1 is a typical voltage-gradient distribution curve (assuming a uniform soil texture). This graph shows that voltage decreases rapidly with increasing distance from the grounding electrode.

B. Step and Touch Potentials

"Step potential" is the voltage between the feet of a person standing near an energized grounded object. It is equal to the difference in voltage, given by the voltage distribution curve, between two points at different distances from the "electrode". A person could be at risk of injury during a fault simply by standing near the grounding point.

"Touch potential" is the voltage between the energized object and the feet of a person in contact with the object. It is equal to the difference in voltage between the object (which is at a distance of 0 feet) and a point some distance away. It should be noted that the touch potential could be nearly the full voltage across the grounded object if that object is grounded at a point remote from the place where the person is in contact with it. For example, a crane that was grounded to the system neutral and that contacted an energized line would expose any person in contact with the crane or its uninsulated load line to a touch potential nearly equal to the full fault voltage.

Step and touch potentials are illustrated in Figure 2.
(For Figure 1, Click Here)
http://www.osha.gov/OshStd_gif/10RF_1.gif
(For Figure 2, Click Here)
http://www.osha.gov/OshStd_gif/10RF_2.gif

C. Protection From the Hazards of Ground-Potential Gradients.

An engineering analysis of the power system under fault conditions can be used to determine whether or not hazardous step and touch voltages will develop. The result of this analysis can ascertain the need for protective measures and can guide the selection of appropriate precautions.

Several methods may be used to protect employees from hazardous ground-potential gradients, including equipotential zones, insulating equipment, and restricted work areas.

1. The creation of an equipotential zone will protect a worker standing within it from hazardous step and touch potentials. (See Figure 3.) Such a zone can be produced through the use of a metal mat connected to the grounded object. In some cases, a grounding grid can be used to equalize the voltage within the grid. Equipotential zones will not, however, protect employees who are either wholly or partially outside the protected area. Bonding conductive objects in the immediate work area can also be used to minimize the potential between the objects and between each object and ground. (Bonding an object outside the work area can increase the touch potential to that object in some cases, however.)

2. The use of insulating equipment, such as rubber gloves, can protect employees handling grounded equipment and conductors from hazardous touch potentials. The insulating equipment must be rated for the highest voltage that can be impressed on the grounded objects under fault conditions (rather than for the full system voltage).

3. Restricting employees from areas where hazardous step or touch potentials could arise can protect employees not directly involved in the operation being performed. Employees on the ground in the vicinity of transmission structures should be kept at a distance where step voltages would be insufficient to cause injury. Employees should not handle grounded conductors or equipment likely to become energized to hazardous voltages unless the employees are within an equipotential zone or are protected by insulating equipment.


(For Figure 3, Click Here)
http://www.osha.gov/OshStd_gif/10RF_3.gif


--------------------------------------------------------------------------------

Footnote (1) This appendix provides information primarily with respect to employee protection from contact between equipment being used and an energized power line. The information presented is also relevant to ground faults to transmission towers and substation structures; however, grounding systems for these structures should be designed to minimize the step and touch potentials involved.

[wtdoor67]

You know we used to slide a bunch of fibers on the wires, put a rope on them and drag them to the area we wanted covered. Take a saw and cut them down in small pieces until certain we could take the whole thing out safely. Also used one of those insulated limb saws a lot. Cut in small chunks until below the primaries.

[Boomer gone soft]

A lot of linemen are under the impression there is nothing to tree work.

As a former wood-tick, I can attest that it is far more involved than donning a pair of gloves and grabbing a chain saw.

If your utility has tree crews, use them. They are specially trained.

If your utility does not have tree crews, open and ground. But remember, the electricity is not the only danger, nor is it necessarily the largest. Trees are unpredictable sometimes even for those who deal with them on a regular basis. Lines under the weight of trees possess tremendous kinetic potential. Those wires will literally take your head off if you are in the bight.

Watch the pinch points of the saw, and ALWAYS be aware of kickback.

There's a million things to say about this subject as Meat has noted.

BE CAREFUL and go home ALIVE.:)

[Ricco]

call for a tree crew...;)

I think this is my first real post here but I second this, This tree crews here are in the same union IBEW 77. Most guys don't call, but it is more hours for them, more hours for us, and IMO safer for everyone. Tree work is a whole different trade imo, I have a journey ticket as a tree trimmer but I still would call a tree crew. Support another union brother;)

[mainline]

We have worked with union tree guys from NY. They were with tamarack tree co. I wish we had them all the time. All we have up here regularly are non-union guys who are hit or miss and get treated like crap.

[west coast hand]

we have tree crews we never cut trees thats a union job out here and you don't take another mans job