These Insulators are still in service. Xcel Energy in MN, St. Paul has 9 miles of tunnels that were dug in the late 1880's and into the 1990's. They were all carved out of sand rock by hand with donkeys to carry the sand rock out. Its realy a maze with upper and lower tunnels and inter connects and I'll admit Ive gotten lost more then once. A lot of old lead DC cables and a lot of asbestos. We installed aot of lead cable back when I started and splicing it is now a lost art. Weve been doing olot of work in them latley to get ready for a light rail link from St. Paul to Minneapolis. The green mine insulators are Hemingray with the number 103 on them and the lighter greenish blue have no embossing. There is a lot of porcelain mine insulators around also. I hope you enjoy the photos, Bob