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Whats a grounding electrode system?

10K views 74 replies 20 participants last post by  Meadow 
#1 ·
Says to connect the separate ground there? :blink: Im confused.
 

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#66 ·
The wording changed slightly in 250.130(C) in the 2014 cycle, where they added an option to connect to a different circuit's EGC:

(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions.
The equipment grounding conductor of a
grounding-type receptacle or a branch-circuit extension shall be
permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system
as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure
where the branch circuit for the receptacle or branch circuit
originates
(4) An equipment grounding conductor that is part of another
branch circuit that originates from the enclosure where
the branch circuit for the receptacle or branch circuit
originates
(5) For grounded systems, the grounded service conductor
within the service equipment enclosure
(6) For ungrounded systems, the grounding terminal bar within
the service equipment enclosure
Looks like this guy was doing it prior to 2014, though... :whistling2:

 
#67 ·
There are only two ways to legally install a 3 prong recp on an old 2 wire circut. One is the method in that picture, the other is installing a GFI, all loaded receptacles will be allowed to be 3prong, if you mark them NO EQUIPMENT GROUND and GFCI PROTECTED(you know, those stickers in the box people always throw away? I save em, cuz they only give you two of those). but they will not actually have a EGC. If you cant run an EGC, and you dont want a GFI, then the plug must be replaced with a 2prong recp

I was in an older house.. The basement was concrete walls, and when it was originally poured they bothered to put metal boxes in the wall... I do believe there was EMT to the box as well, but where the other end of that emt was I will never know.. in a wall somewhere Im guessing.. They wanted a 3prong plug.. well.. although Im sure this isnt quite legal, I ohm'd the box to neutral, and it was very low, as good as any other circut in a modern house with 3 wire.. So I put a ground pigtail in the box and installed a 3prong recp. Even a plug checker and various multimeters confirmed it was as good a ground as any.

However I have never seen a concrete encased metal box and emt be mentioned in the code book as a grounding electrode :)
 
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