When did polarized plugs come out?

Answer 1

I am a retired 74 year old electrician, plumber,& hvac mechanic. This is not a one answer question. I helped my dad wire houses when I was 12 years old. This is an easy question to answer. Polarized plugs actually came out in 1914. They were never well accepted, so, here is what I can tell you. If you have an old lamp pay more attention to the cord and the socket. When polarized plugs and the pole plugs finally became acceptable to the public, the electric companies made three prong adapters available. Simply because, most homes only had two prong receptacles. So that people merely cut off the plug and replaced it with a two prong plug, so, you are finding Bakelite plugs with no cover cap on them. Here is what to look for. To date your lamp or appliance. Asbestos or cloth covered cords ended in the early 50's. Bakelite plugs ended about the same time, then we grew into the molded cords. If your cord is stiff composite of rubber and plastic it ended in the mid 50's. If it is a clear wire it ended in the 60's. Also look at your socket. If it is porcelain it could have ended in the 40's or 50's as well as many of them being Bakelite. I can't continue beyond that because at that point repros are being made and we are not interested at this point in modern lighting's another thing to look at in your old light, does it have a ground wire? if it does it is mid 20th century and not antique.