when were ground wires 1st required

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Joseph Alexander

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Can anyone tell me what the code was that first required the placement of a ground conductor in wiring systems. such as NM W/ Ground etc... I think it was around 1960 but I'm not sure.
thanks alex
 
I have no idea but from this site

Modern NM (nonmetallic) cable, which includes a bare grounding wire, was introduced in 1965. The wire insulation and the outer sheathing is made of plastic vinyl; the gauge of the wire is printed on the sheathing. A "12-2" cable, for example, has two 12 gauge insulated conducting wires. Today almost all home wiring is NM, except where otherwise prohibited by code.
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The first time 210-7 states "Receptacles installed on 15- and 20-ampere branch circuits shall be of the grounding type" is 1975.

Prior to that, there was no requirement to install a grounded recep. If you installed a grounded recep, it shall have been grounded.
 
I found this
http://www.dslreports.com/r0/download/1409151~fa6fd56bdb73efbce4b95d02212199e5/Wiringhistory.pdf
Until the early 1960?s, most NM cable for residential use did not have a grounding conductor. However, changes in the 1962 Code that mandated equipment grounding for all branch circuits popularized the use of NM cable with ground. Earlier versions of NM cable with ground permitted the grounding conductor to be No. 16 AWG for 14 and 12 gauge copper NM, and No. 14 AWG ground for 10 gauge copper NM. In 1969, new requirements no longer permitted an undersized grounding conductor for 14, 12 and 10 gauge NM cable.
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I also saw somewhere that the 1928 code required a grounding means to some degree??​
 
090322-1138 EST

I believe equipment with a 3 prong plug started to become available mid-1950s.

My guess based on recollections is about 1955. It would not have been 52 or 53 because discussions on this change relative to test equipment did not take place until after EDG (Electronics Defense Group) moved from East Engineering to the Cooley building on North Campus in the fall of 53.

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1959 is the first mention of NM having a ground wire.

336-2 Construction. .... In addition to the insulated conductors, the cable may have an approved size of uninsulated or bare conductor for grounding purposes only.
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M. D. said:
I found this
http://www.dslreports.com/r0/download/1409151~fa6fd56bdb73efbce4b95d02212199e5/Wiringhistory.pdf
Click to expand...
That fits my memory ... Daddy had a house built in Fall/Winter 1961/1962. I was a Ham and wanted a grounded receptacle in my bedroom/shack. The electrician said he didn't use them for 115V with non-conductive floors but ran me a 230 outlet and labeled the panel for Air Conditioner. 115 outlets were 2 wire.

The ground floor was a slab with exposed brick on the slab in 3 rooms; he ran 14-2WG and 3 wire outlets downstairs. The ground was reduced size.

This was in the "PLEASE USE MORE ELECTRICITY" day ... we had CeilHeat electrical resistance heat in all rooms but the bath's; they had wall resistance units. Each room had its own thermostat.
 
In 1947 the NEC required the laundry outlet in dwelling units to be a "3-pole type designed for grounding". 1947: 2124b.

This was expanded in 1956 to "open porches, breezeways, garages, and the like which may supply equipment to be used by persons standing on the ground". 1956: 2124b.

In 1959, type AC was required to have "an internal bonding strip of either copper of aluminum in intimate contact with the armor for its entire length". 1959:334-2(b).

1962 brought about the requirement for branch circuits to "include or provide a grounding conductor to which the grounding contacts of the receptacle or cord connector shall be connected. 1962:210-7.
 
090324-1623 EST

Today I looked in my dad's home and both the basement and kitchen had 3 prong outlets, and there was NM labeled 2-14 with G. This appears to have been a requirement in September of 1958. I can precisely define this time because highway construction required that the home be moved. The basement was completely new and some changes were made in the kitchen.

I am still guessing that about 1955 was close to the availability of 3 prong outlets.

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