Grounded systems
According to the limited research I was able to do, the 1947 NEC (National Electric Code) was the first to require any grounded receptacles. At this time, the requirement was applicable only to laundry rooms. The receptacle used was the now obsolete NEMA 10 series in the 15 amp configuration. In 1951, the code recognized the new NEMA 5-15R grounded receptacle, which is the current standard for 15A 125V rated receptacles.
The 1956 NEC required grounded receptacles also in garages, basements, and outdoor locations. I'm still trying to find out when they became required in kitchens, but believe it was by 1959.
The 1962 code was the first to require all branch circuits to include a grounding conductor.
The educational wing of the church I belong to was built in 1959, and all receptacles have always been the grounding type. It's a masonry building, so all wiring is in metal conduit, which serves as the grounding method.
The information above is from various online sources, and therefore I cannot guarantee complete accuracy. On my next trip to the downtown library, I'll see if they have copies of the old code books, so I can verify this info.
According to the limited research I was able to do, the 1947 NEC (National Electric Code) was the first to require any grounded receptacles. At this time, the requirement was applicable only to laundry rooms. The receptacle used was the now obsolete NEMA 10 series in the 15 amp configuration. In 1951, the code recognized the new NEMA 5-15R grounded receptacle, which is the current standard for 15A 125V rated receptacles.
The 1956 NEC required grounded receptacles also in garages, basements, and outdoor locations. I'm still trying to find out when they became required in kitchens, but believe it was by 1959.
The 1962 code was the first to require all branch circuits to include a grounding conductor.
The educational wing of the church I belong to was built in 1959, and all receptacles have always been the grounding type. It's a masonry building, so all wiring is in metal conduit, which serves as the grounding method.
The information above is from various online sources, and therefore I cannot guarantee complete accuracy. On my next trip to the downtown library, I'll see if they have copies of the old code books, so I can verify this info.
