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The History of Grounded Receptacle in Residential
The History of Grounded Receptacle in Residential
Chelan Home Inspections
 


I have written about electrical history before such as the grounding of receptacles in reference to laundry circuits which begins with the 1947 NEC (which was the first required grounded receptacle in dwelling units (residential) to be a "3-pole type designed for grounding").
So let us start with the first code section to reference grounding type of receptacles in residential (dwelling units).

1947 NEC
2124 Receptacle Outlets Required.
 
(b.) In Dwelling Occupancies.
In dwelling occupancies, in every kitchen, dining room, break/aet room, living room, parlor, library, den, sun room, recreation room, and bedroom, one receptacle outlet shall be provided lor every 20 linear ft. or major fraction thereof of the total (gross) distance around the room aa measured horizontally along the wall at the floor line. The receptacle outlets shall, insofar as practicable, be spaced equal distances apart. At least one receptacle outlet shall be installed for the connection of laundry appliances. This receptacle shall be 3-pole, of a type designed for grounding.

Receptacles in floor outlets shall not be counted as part of the required number of receptacle outlets unless located close to the wall.
So we can see here the sentence “At least one receptacle outlet ... more

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