Grounding Electrode System Fundamentals

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ActionDave said:
... There is only one Grounding Electrode Conductor.
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Not true. There is only one GEC per electrical-end connection, but there can be multiple GEC's each with its own electrical end connection.

For the most part, the term "grounding electrode conductor" is singular in usage. However, 250.32 and 250.64 both contain the term "grounding electrode conductor(s)".
 
Smart $ said:
... may or may not...

I do realize CMP's are stubborn when it comes to any proposal to make the wording explicit. The majority of times, what is clear in their heads is not clear on paper, but they'll insist that it is.
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PS: If what you are saying is true, 250.68(C) is in the wrong section. Should be moved under 250.64(F) and include wording to the effect of connections other than directly to qualifying electrodes...
 
Smart $ said:
I understand what you are saying and I'm not against it if that is the true intent... but nothing in the wording of 250.68 or (C) thereunder says exactly what you are saying. For example, nothing says metal water pipe entering a building which may of may not qualify as an electrode but it is the same location where a qualifying electrode connection is made, or building steel which does not qualify as an electrode, and CEE is referenced by word in (C)(3). IMO, there should be something in there that states what you are saying and there is not.

I do realize CMP's are stubborn when it comes to any proposal to make the wording explicit. The majority of times, what is clear in their heads is not clear on paper, but they'll insist that it is.
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I hear you. It doesn't help matters that the code has changed principles over the last 20 years. It used to be implied that a grounding electrode was a grounding electrode as long as the electrical continuity remained; they have changed their mindset that an electrode stops being an electrode when the conditions they place on it begin to fall away.

Bob Badger and I had a knockdown drag out session over this back in the '05 cycle, which resulted in a fairly intense amount of research into what the code used to say back when they trusted metal water pipes throughout a structure, as compared to later cycles. Even now, there are likely gaps between the old and new way of looking at certain grounding electrodes, and there are discrepancies among the written opinions of the CMP members themselves. These should eventually all get tuned in as proposals flesh out 250.68(C) - assuming they put out some kind of document like the former ROPs and ROPs back out that we mere mortals can look at and submit comments on and study.
 
George Stolz said:
...If it didn't take 45 minutes, three beers and four cigarettes to find it, I might go looking. Summary?
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My "comment" underlined...
(C) Other Than Grounding Electrode Connections.
Grounding electrode conductors and bonding jumpers shall be permitted to be connected at the following locations and used to extend the connection to an electrode(s):

  1. Interior metal water piping, continuous with a metal underground water pipe electrode, located not more than 1.52 m (5 ft) from the point of entrance to the building

    Exception: In industrial, commercial, and institutional buildings or structures, if conditions of maintenance and supervision ensure that only qualified persons service the installation, interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall be permitted as a bonding conductor to interconnect electrodes that are part of the grounding electrode system, or as a grounding electrode conductor, if the entire length, other than short sections passing perpendicularly through walls, floors, or ceilings, of the interior metal water pipe that is being used for the conductor is exposed.

  2. The metal structural frame of a building shall be permitted to be used as a conductor to interconnect electrodes that are part of the grounding electrode system, or as a grounding electrode conductor. Hold-down bolts securing the structural steel column that are connected to a concrete-encased electrode that complies with 250.52(A)(3) and is located in the support footing or foundation shall be permitted to connect the metal structural frame of a building or structure to the concrete encased grounding electrode. The hold-down bolts shall be connected to the concrete-encased electrode by welding, exothermic welding, the usual steel tie wires, or other approved means.
  3. A rebar type concrete-encased electrode installed in accordance with 250.52(A)(3)with an additional rebar section extended from its location within the concrete to an accessible location that is not subject to corrosion shall be permitted for connection of the grounding electrode conductor and bonding jumpers. The rebar extention extension shall not be exposed to contact with the earth without corrosion protection.
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Don't forget kids, the 5 foot part refer's to interior connections. Code states a metal water pipe in contact with soil for at least ten feet qualifies as a grounding electrode. Such a pipe is often run on the exterior. But you can only connect bonding jumpers on the interior portion within 5 ft of where it enters the building. So this leads to it's ok to connect the gec on the exterior more than 5' from its entry point to inside, but no jumpers till you get inside.
 
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macmikeman said:
Don't forget kids, the 5 foot part refer's to interior connections.
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I think you are the only one that effects. :cool:

I have never installed or seen an GEC connected to a waterline outside the building. Something about them being buried far below the surface keeps me from even thinking about it.
 
iwire said:
I think you are the only one that effects. :cool:

I have never installed or seen an GEC connected to a waterline outside the building. Something about them being buried far below the surface keeps me from even thinking about it.
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I can send you lots of pictures of it if you like.......:happyyes:
 
iwire said:
I think you are the only one that effects. :cool:

I have never installed or seen an GEC connected to a waterline outside the building. Something about them being buried far below the surface keeps me from even thinking about it.
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You wouldn't normally connect to an existing water line at a location outside of a building, if you are there when a new water line is being installed you would have the ability to easily connect to it outside and it would not be a code violation, just like it is much easier to connect to a CEE while the footing is under construction then after it is done.
 
kwired said:
You wouldn't normally connect to an existing water line at a location outside of a building, if you are there when a new water line is being installed you would have the ability to easily connect to it outside
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We build a lot out of the ground but we still dont do that.

Easy?

We would have to have to be ready when the plumbers where ready and have the inspector out to look at it before it could be back-filled. And then we would still have to jumper the meters and backflow preventers located inside

Much easier to do inside for us. In Mikes case I think the water meter is outside as well.
 
iwire said:
We build a lot out of the ground but we still dont do that.

Easy?

We would have to have to be ready when the plumbers where ready and have the inspector out to look at it before it could be back-filled. And then we would still have to jumper the meters and backflow preventers located inside

Much easier to do inside for us. In Mikes case I think the water meter is outside as well.
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I said it would be easier to connect if you were there when the water line was being installed, if it needs inspected before being covered that may be a problem but it was still easier to install while the trench was open:p
 
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