I live along an abandoned railroad right-of-way that currently serves triple duty as a paved trail, a major drainage culvert, and an easement for my local electric utility. This combination gets interesting — the culvert can go from one inch to six feet deep in less than ten minutes in a heavy storm, thus covering the trail; the easement carries a 34 kV line, right along the trees in our back yards, so the utility comes out and just slices off the backs of the trees once in a while; and at least once, they’ve gotten a truck stuck in the mud left by the first scenario.
Those lines have been there for decades…probably put most of them up when the railroad went in. They sit on two sets of poles — a series of double-pole units to carry the 34 kV, and a line of single poles that help carry the 240 V house lines, cable TV, etc.
Until this month, anyway. The utility updated the substation at the end of our block, and are now putting in all new poles and streamlining the entire operation. I used to work in the power distribution industry as an engineer, so I’m interested in the entire process. It’s hard to tell sometimes what they’ve done in a day (other than utterly ruin the grass on either side of the trail, but that can’t be helped), but they’re getting a lot done.
The primary push right now is to replace the line of double poles with a line of much taller singles. The doubles held the big line up between 40 and 50 feet. The singles are much taller (closer to 70 or 80), which may get them far enough from the trees that they won’t have to trim them off anymore. (They maintain 15 feet from the 34 kV line.) Looks as if they are trying to reduce the total cabling as well — pole has a static wire along the top, three lines for the three-phase under that, and every pole has a line to ground.
It’s hard to see the ground line here…it is behind the pole, held out from the side to avoid shorting the live lines, then comes back to the pole and straight to the ground. Very nicely done, actually. It’s inspired me to re-do the grounding for my antennas (which, sadly, seems to be under poison ivy at the moment).
As they put up the new poles, they take down half of the double pole. I’m not sure what their goal is with the other half — it not only carried the big lines, but also the 240, with a single pole midway between the doubles to serve the homes. My new HF antenna came down about an hour after it went up due to a random tree branch, but I don’t want to put it back up if they are going to take those smaller poles out — they’d have to re-route the line to my house, and I do not want my antenna situated where one can fall on the other.
I’ve not caught them actually putting in a new pole, but they’ve left the old ones out for now. It looks like about five feet is embedded in the ground (which is enough, given that the wires themselves help stabilize things a bit).
Not sure how much of the new poles get buried, but it’s almost certainly more than five feet.
At the end of the street, the lines change direction, so they’ve also installed one of those metal monsters, because the wood poles can’t bear a uni-directional load like that without a lot of help. Thing is bloody huge, and has me wishing I could safely pop an antenna on the top of it.
They’ve made extensive use of pulleys on this project. As they’ve installed the poles, they’ve attached pulleys to the ends of the insulator arms, then run the cabling over that. This allows them to keep the line slack for the early work. When they have the run done, they pull the lines tight (well, tight enough. They do contract in the winter, pull them too tight and they’ll snap something when it’s 80 degrees colder than today) and put the cables properly on the arms.
From what I can tell, this will run for at least a mile after the end of the trail, but I’m not sure where it will terminate. I lived down there for a while, and there isn’t much to run it to.
Overall, fun to watch, and I’ve learned a bit about current state of the art.