The life of a telephone pole begins with a very tall straight tree
… Our eyes, cleared of all belief, lift up in disbelief their fearsome crowns of bolts, trusses, struts, nuts, insulators and barnacles that make up those weathered encrustations of electrical debris – each a Gorgon’s head, which , grabbed right, could stun us to stone.
Yet they are ours. We made them. See here, where the linemen’s cleats have roughened a second bark on the bald trunk. And these spikes have been driven in sideways at intervals convenient for human legs …
Unpardonably, I snuck into John Updike’s 1963 poem, “Telephone Poles,” pinched a few of its crude lines and locked them into whitewashed prose of their crucial structure and cadence. Even so, they still give us a break. Because we live in the middle of a forest adapted to our own exacting specifications and we rarely give a second thought to the forest or the trees.
I’ve always referred to them as telephone poles, although the more inclusive “utility poles” are probably the best term, especially since our ubiquitous cell phones have led so many to abandon their land line service. (Which begs the question, what about all those millions of miles of phone lines hanging up there? Are they just unused or are they maybe reused? Anyone know?)
Francis Robert, inventor of the first functional electric telegraph, is also credited with erecting the first poles in 1816, suspending eight miles of cable in west London. In 1843, Congress awarded $ 30,000 to Samuel Morse (renowned in Morse code) for the construction of the first American telegraph line from Washington to Baltimore. In seven years, more than 12,000 miles of telegraph poles have dotted the American landscape.
The typical utility pole is approximately 40 feet long, of which 6 feet are buried in the ground. In urban environments they are usually spaced about 125 feet apart, while in rural areas the distance is more like 300 feet. (Distances and post heights vary widely depending on local terrain and clearance requirements.)
For economic reasons, many utility poles are responsible for carrying a variety of power and communication lines. At the top of a typical common-use pole are high-voltage sub-transmission lines that carry electricity from regional substations to local substations. Below these are low voltage distribution lines carrying electricity from a local substation to service points supplying individual customers.
Communication cables (for telephones, cable TV and computer networks), if present, are separated from lower power lines by a âcommunication worker safety zoneâ. And many poles are also used to support lampposts, traffic lights and Christmas decorations. Joint use indeed.
Some 130 million wooden utility poles are in service in North America. In the United States, the American National Standards Institute (ANSI) has defined standards for their manufacture, dimensions, manufacture, preservation, marking, handling, storage and inspection.
Most of the posts are made from southern yellow pine, Douglas fir, or western red cedar, although other conifers are also used. According to the North American Wood Pole Council, only 7 percent of trees in a typical plantation will have the length, straightness, taper, and other characteristics needed for a utility pole.
After harvest and transport to the lumber yard, the trunk is debarked, shaped to make it as straight as possible, and graded to ANSI standards. Holes are drilled to allow fastening of hardware and to provide access to preservatives inside the post. They are then seasoned by air drying and oven drying or steamed in long pressurized cylinders called retorts.
Without the final stage of infusion with conservatives, a pole would have the chance to hold out for five years against the assaults of an army of decomposers. Even with preservation, the useful life of a utility pole is on average only about 70 years. (One of the biggest threats to a pole’s longevity is damage from the woodpecker, which opens its interior to insects and fungal invaders.)
Typically, one of the five preservatives approved by the EPA is pumped into a long retort containing a cart supporting a few dozen poles. Preservatives are pressed into the wood cells under high pressure for a period of time that varies depending on the size of the posts, the species of trees and the type of preservative. The entire process, from tree selection to preservation, is beautifully illustrated in a five minute YouTube video (youtube.com/watch?v=-R7HckUilVA).
Gluing a post into the ground to keep it is an art form in its own right. If you’re curious, especially if you like trucks and cool tools, take a look at this 14-minute post adjustment training video.
Things have changed somewhat since Updateike saw an Ipswich lineman climbing up a telephone pole with all of his tools hanging from his belt. Today, most poles are accessible in bucket trucks. Less macho than cutting your way through pointe, maybe, but still pretty cool.
Ken Baker is a retired professor of biology and environmental studies. If you have a natural history topic that you would like Dr. Baker to consider for an upcoming column, please send your idea to [email protected]