While high-voltage transmission lines are probably the most visible components of the electrical grid, they’re certainly among the least appreciated. They go largely unnoticed by the general public — quick, name the power line closest to you right now — at least until a new one is proposed, causing the NIMBYs and BANANAs to come out in force. To add insult to injury, those who do notice the megastructures that make modern life possible rarely take a moment to appreciate the engineering that goes into stringing up hundreds of miles of cable and making sure it stays up.
Not so the Bonneville Power Administration, the New Deal-era federal agency formed to exploit the hydroelectric abundance of the Pacific Northwest of the United States, which produced this 1950 gem detailing the stringing and sagging of power lines. Unsurprisingly, the many projects needed to wire together the often remote dams to the widely distributed population centers in an area that was only just starting to see growth began in the BPA’s offices, where teams of engineers hunched over desks worked out the best routes. Paper, pencil, and slide rules were the tools of the trade, along with an interesting gadget called a conductor sag template, a hardware implementation of the catenary equation that allowed the “sagger” to determine the height of each tower. The conductors, either steel-cored aluminum or pure copper, were also meticulously selected based on tensile strength, expected wind and ice loading, and the electrical load the line was expected to carry.
Once the engineers had their say, the hard work of physically stringing the wires began out in the field. One suspects that the work today is much the same as it was almost eighty years ago, save for much more stringent health and safety regulations. The prowess needed to transfer the wires from lifting sheaves to the insulators is something to behold, and the courage required to work from ladders hanging from wires at certain death heights is something to behold. But to our mind, the real heroes were the logistics fellows, who determined how much wire was needed for each span and exactly where to stage the reels. It’s worth sparing a moment’s thought for the daring photographer who captured all this action, likely with little more than a leather belt and hemp rope for safety.
Yeah, attached to a swinging ladder with a leather strap around the waist high above the ground.
That’s a job I wouldn’t volunteer to do.
My Dad did that kind of work and live high tension as well before WWII.
I had to lookup “BANANAs” – build absolutely nothing anywhere near anything (or “anyone”)
Thanks to Mr. George Carlin, I knew what “NIMBY” stands for. “Build more prisons, but not here” chuckle.
I think there will be few places in the world where powerlines can sag as in the Netherlands.
On September 2nd 2022 there was a bit of an accident, combined with a failures of 3 safety circuits. As a result high voltage lines (150kV) overheated and created enough smoke to be as dense as mist. Those high voltage power lines sagged so much that the shorted the (measly) 1.5kV powerlines of trains. and quite a lot of train switch boards had to replaced afterwards too. The overload lasted 4 minutes before someone managed to manually turn the power off. You can watch the thing on youtube “stroomstoring flevoland 2022”
I named the powerline nearest to me “John” because it’s a good dependable name.
John doesn’t like sharing with trees though.
In Maryland the transmission company is testing public opinion on running a new 500KV high-tension line through northern Frederick, Carroll, and Baltimore counties. It’s not going well because of these things: 1. This power line only benefits data centers in NOVA, so most people around here think should try and build nuclear on that side of the Potomac. 2. Carroll county is the Texas of Maryland, with many ornery farmers. 3. Northern Baltimore county is horse country, with rich people who paid dearly for their views. So even if they eminent domain it, I don’t expect the footings to cure properly without armed guards. The transmission company has already said this is just their least expensive option and that they definitely could retrofit an existing line to work perfectly well.
Points 2 and 3 really got me in support of that 500kv line.
The Maryland horse people are insufferable, and those farmers stay in business on government handouts. Big motivation for moving out of Maryland was that terrible state tax rate…
From what I recall, you’d hardly the those transmission lines anyway, since the terrain is so varied.
Working on that suspended ladder with just that belt… That’s faith in your equipment. I’m certain it’s powerful incentive to pay attention and keep your mind on the job. Safety Third!
I have been sport sclimbing for quite some years. At first I had a “healthy” fear of heights, but after a while you get used to it and a few years later it bothers you not at all and the danger is in getting nonchalant. Even when climbing in the alps in a wall a few hundred meters high, you’re just having fun and admire the view and enjoy the narrow ridge you have for your lunch. And then, when you skipped climbing for a few years and take it up again, the old fear of heights is back, but it quickly fades within a few months when climbing twice a week.
I used to jump out of perfectly serviceable airplanes to fall for a mile or more for the fun of it, and climbed radio towers for work, but I could never get over the notion of “this isn’t worth the risk” when rock climbing. And an indoor wall with an autobelay just isn’t any fun, for me anyway.
I worked in the utility industry and weirdest thing about power lines is the standing waves and galloping as it’s called, that wind can cause and makes lines sway and short phase-phase. Especially in hot weather when the wire length is greater. You add spacers/dampers to stop this.
Another was the 240kV lines, of course to work on them you put ground chains on the lines to prevent charge buildup, lightning hits etc. from killing the linesmen. Well, the project manager forgot to remove them after the work was finished, control room switched in the line and massive overload. Breakers tripped but it almost took out the grid in 1/3 the country. That is a short-circuit.
Damned colonials, circular mills CM, utter bollocks. Just had to stop the video at that stage, lest permanent damage be incurred.