According to Wikipedia, on a subject entitled Cheater Plugs, "In 1969 Underwriters Laboratories mandated three-prong plugs on major appliances for safety", and "At that time, only half of the receptacles in US homes were three-prong." Additionally, "In 1971, the US National Electrical Code (NEC) required grounded receptacles in all locations of the home (effective January 1, 1974)."
Dave Rossetti Sent from my Verizon Motorola Droid On Aug 7, 2019 1:29 PM, David Rossetti <[email protected]> wrote: > > Just as a data point, the house I grew up in was built around 1952 and used > the two equally sized outlets. Seems the addition, added on in or about 1961 > used the three pronged outlets. I also remember buying lamps in 1977 that had > two equally sized prongs, something you won't see today. > > Dave Rossetti > > Sent from my Verizon Motorola Droid > On Aug 7, 2019 11:42 AM, LARRY PICARD <[email protected]> wrote: > > > > I live in an older home. > > Before the knob and tube wiring was replaced a number of years ago, the > > original electrical outlets had only two slots and they were both the same > > size. > > Does anyone know when three prong plugs and polarized plugs and their > > respective receptacles came into use? > > _______________________________________________ > > Boatanchors mailing list > > [email protected] > > https://puck.nether.net/mailman/listinfo/boatanchors > _______________________________________________ > Boatanchors mailing list > [email protected] > https://puck.nether.net/mailman/listinfo/boatanchors _______________________________________________ Boatanchors mailing list [email protected] https://puck.nether.net/mailman/listinfo/boatanchors
