I came across an article from Hydro One about replacing wood poles in Ontario. I thought it worth passing on. http://www.newswire.ca/en/story/1181909 ... eliability
Another interesting article explains why porcelain suspensions, that have been in use for a 100 years, are being replaced by composite insulators which have an unknown lifspan. http://tdworld.com/overhead-transmissio ... insulators
My understanding from a Hydro One employee, if I got the story straight, is that about 2006 Hydro One was given a ten year mandate to replace all Insulators in Ontario with composite styles. That means in a couple years from now, no pintypes, no glass and no porcelain will be in the air. The exception to this may be glass suspensions which are not rendered defective by cement growth the same way the porcelain discs are.