History of Grounding

[tom baker]

I am working on a brief history of significant changes to grounding
Here is what I have so far
1923 NEC - First mention of driven rod or pipe electrodes
1925 NEC - Driven rod electrodes now called ?artificial?, 8 ft long, 1/2? rod or ?? pipe
If resistance >25 ohms, requires 2 electrodes spaced 6 feet apart
1951 NEC - Ten feet of less of metal water pipe must be supplemented with additional electrode
1947 - Grounding receptacles required for laundry
1956 - Grounding receptacles required for garages, basements, outdoors
1962 - All branch circuits must include a grounding conductor
16 AWG for 12 and 14 gage circuits, 14 AWG for 10 gage circuits
1963 - Research paper presented by H.G. Ufer at IEEE Conference
1969 - Full size ground required for circuits
1971 - Water pipe electrode must be supplemented with additional electrode
1971 - Ufer ground must be used ?If Available?
1974 - NFPA TIA ?if available? does not mean it has to be used.
1999 - Additional electrode must have resistance of 25 ohms or less, or be supplemented with additional electrode
1993 - Interior metal water piping more than 5 ft from point of entrance can not be used as part of the grounding electrode system
1999? - No longer allowed to use use neutral for frames of ranges, etc
2002 - Can't reground neutral if creates a parallel path to separate buildings
2005 - Ufer ground must be used when present
2005 - Bonding added to title
2008 ? Supplementary ground rod changed to auxiliary ground rod
2008 - Ground is now the earth
2008 - Can not reground the neutral at separate buildings

Need to know: when structural steel/metal was added
When was bonding added, my 1956 NEC doesn't mention
And the above may not be 100% accurate. I don't have code books before 1968

 

[480sparky]

.........
Need to know: when structural steel/metal was added
When was bonding added, my 1956 NEC doesn't mention
And the above may not be 100% accurate. I don't have code books before 1968

Do you have an Article number for the years around that area you are searching in?

 

[SegDog]

pre-96

pre-96

FYI,

I am certain that 3 wire dryer/range neutral frame grounds are called pre-96.

Best of luck

Wally

 

[George Stolz]

And the above may not be 100% accurate. I don't have code books before 1968

Tom, check out Antique's site here. Lots of old code books free for the browsing. I am sure that ground rods and water pipes were mentioned prior to 1923, they were called lightning arresters (for example, page 32 of 1915).

 

[JohnJ0906]

FYI,

I am certain that 3 wire dryer/range neutral frame grounds are called pre-96.

Best of luck

Wally

That requirement changed in the '96 NEC. (Neutral no longer allowed to ground range/dryer frames)

 

[JohnJ0906]

And thanks for the post, Tom. Interesting.

 

[bphgravity]

The first edition of the code to contain the 25-ohm section was the 1918 edition. Also in the 1918 edition, the first allowance for pipe electrodes became code. The original requirement permitted a minimum of a 1-in pipe with no less than 4-ft? of surface to exterior soil. The 1923 edition added the driven rod.