See how wood poles have achieved a long, documented record of performance in service with utilities throughout North America.
woodpoles.org
It's not, it's the most expensive part.
"The 2013 OSU survey collected pole purchasingdata, with 86 utilities reporting they purchased onaverage 5,845 poles a year. When compared to thetotal pole population, the estimated pole replacementrate would be 1.12 percent a year, compared to 0.7percent indicated in the 2000 survey. However, thisrate must be viewed with some caution since thepurchases include poles for new line construction."
"Based on the 0.6 percent replacement rate, theaverage pole service life would easily reach 80 yearsin many areas of the country, far in excess of theperceived 30 to 40 years. Thus, old wood does notmean weaker wood.While service life will vary among utilities, if we lookin most utility systems, we see enormous quantities oflines installed in the 1950s where the vast majority ofthe poles remain in service. In 2014, the Los AngelesDepartment of Water and Power reported that morethan half of 320,000 poles in service were 50 years orolder, with some exceeding 90 years or longer."
Telephone pole cost
A telephone pole costs
$1,200 to $5,600 with installation or
$100 to $900 for materials alone. A telephone pole is also called a utility pole, power pole, or electric pole. Most telephone poles are
30 to 45 feet tall and made of wood. Prices are higher for metal, concrete, or fiberglass poles.
And google says there's 185,000,000 poles in the US.
So with a life of only 50 years at $5k each thats 18.5B spent per year including installation. Total US electricity was 488B so 4%. Add in maintenance and repairs plus upgrades maybe 5%. Metal structures are more but also last a lot longer and no maintenance. Another 5% for the additional structures and 5% for the substations and such. There's no way its over 20%