400 amp service ground rods

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jap said:
The grounding electrode "System" which would be the rods, underground metal water pipe, concrete encased electodes, ground rings or the like would be where the "Jumpers" would come into play for tying them all together and therefore 250.66.

The "Ground Rods Only" bonded together are considered a single grounding electrode system but only one part of a larger group of grounding electrodes.


JAP>
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I disagree, look at 250.50 which states that "all grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the the grounding electrode system".
 
jeremy.zinkofsky said:
Check out 250.66(A) which states that the sole connection from the service bond to the first ground rod shall not be required to be larger than 6 AWG copper or 4 AWG aluminum. Now look at 250.53(C) which requires the conductor connecting multiple ground rods to be sized in accordance with 250.66 which requires that you use table 250.66....
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It was never intended that GEC going to a ground rod be larger than 6AWG. 2017 code straightened that out making it clear that connections to ground rods that don't extend to other types grounding electrodes are not required to be larger than 6AWG.
 
jeremy.zinkofsky said:
Wasn't trying to get off subject. NEC article 250 is hard to generalize and needs additional scrutiny when comparing against each specific installation.

All i was trying to say was that the contractor needs to be mindful of how each of the available grounding electrodes are to be connected to form the grounding electrode system. Conductor size requirements are dependent how each grounding electrode is connected to the main service bond, whether parallel or in series.
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So is it your interpretation that a #6 would be needed to the "first" rod only, then upsized to the 2nd and the 3rd rod?

JAP>
 
jeremy.zinkofsky said:
I disagree, look at 250.50 which states that "all grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the the grounding electrode system".
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That's true,

but a rod or pipe is only 1 type of of those 7.

JAP>
 
ActionDave said:
That wording was added in '08 I think, it screwed up the intent of 250.66(A). 2017 code makes it clear all is needed is 6AWG for ground rods.
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My feeling (worth absolutely nothing in the real world) is that '08 wrote "sole connection" when they really meant "connected solely"
 
jeremy.zinkofsky said:
Check out 250.66(A) which states that the sole connection from the service bond to the first ground rod shall not be required to be larger than 6 AWG copper or 4 AWG aluminum. Now look at 250.53(C) which requires the conductor connecting multiple ground rods to be sized in accordance with 250.66 which requires that you use table 250.66.

Now for example, if the size of the largest service entrance conductor is between 350 - 600 kcmil then you are required to use a 1/0 AWG grounding electrode conductor everywhere except for at the locations described in 250.66(A) thru (C). As stated previously, 250.66(A) allows for a maximum 6 AWG copper to be used for the sole connection from the service bond to the first ground rod where table 250.66 requires a 1/0 AWG for the conductor connecting multiple ground rods.

There are similar exceptions for sizing the conductor that is the sole connection from the service bond to the ground ring and/or concrete encased electrodes. If you wire the ground ring and ground rods in series you could easily have different size conductors for the interconnection of the various required electrodes.

I'm not saying it makes sense, just interpreting what the NEC requires.
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Read 250.66(A) again. 2017 NEC
 
jeremy.zinkofsky said:
I will when 2017 takes effect. Still on 2011...
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The code cycle is not what's critical. 2017 just clears up a mess made by the cmp in 2008.

It has never been a requirement that anything larger than 6AWG be used for a GEC for ground rods under any code cycle. The change in 2008 was an attempt to make that clearer, but certain people read it the wrong way and controversy followed.

There is no reason to run anything larger than a 6AWG GEC for ground rods and with that understanding the "sole connection" wording can be interpreted as "connected solely" like GoldDigger mentioned with a clear conscience.
 
stevenje said:
Point well taken. You did not mention what year code book that you were quoting from.
So it really comes down to what year code book that the OP is currently under, before a definitive answer can be given.
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Ummm, no. It's stupid to use 6AWG to the first round rod and then jump up to 1/0 to the second rod, definitively.
 
ActionDave said:
Ummm, no. It's stupid to use 6AWG to the first round rod and then jump up to 1/0 to the second rod, definitively.
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I agree, but that is the way the current code is written. There are a lot of dumb requirements we need to follow and try to make sense of, ASHRAE 90.1 is a great example of that.
 
ActionDave said:
The code cycle is not what's critical. 2017 just clears up a mess made by the cmp in 2008.

It has never been a requirement that anything larger than 6AWG be used for a GEC for ground rods under any code cycle. The change in 2008 was an attempt to make that clearer, but certain people read it the wrong way and controversy followed.

There is no reason to run anything larger than a 6AWG GEC for ground rods and with that understanding the "sole connection" wording can be interpreted as "connected solely" like GoldDigger mentioned with a clear conscience.
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I agree, poor grammar pre-2017 but the intent hasn't changed. I believe that this was one of our CM's "proposals".
 
infinity said:
I agree, poor grammar pre-2017 but the intent hasn't changed.
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To expand on intent a little bit. How exactly does that come into code interpretation? Intent is more often than not driven by cost not common sense and the inspectors that i have dealt with rarely care about intent. They seem more interested in seeing literal compliance with the wording of the code.
 
stevenje said:
I am in total agreement with you Dave. I side-tracked myself with trying to make the point that some answers depend on what code cycle that is being enforced.
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Guys, it doesn't matter what we think is smart or stupid. All that matters is that we pass inspections and meet deadlines. Unfortunate and dangerous reality of our business.
 
jeremy.zinkofsky said:
Guys, it doesn't matter what we think is smart or stupid. All that matters is that we pass inspections and meet deadlines. Unfortunate and dangerous reality of our business.
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It does matter If you've got an inspector that's costing you money by making you upsize wire and install things that aren't actually required.

Passing inspections and deadlines are a reality of our business but not a dangerous reality.

JAP>
 
So I went and did a little research and I was slightly mistaken. The wording "sole connection" goes back at least as far as 1988, that's the oldest code book at our shop. 2014 has some horrible mish mash about multiple ground rods, I didn't even try to sort it out. That means I was misremembering a little bit.

It was not the code language that changed round about 2008 it was some nutcase that started a controversy about the wording and how 250.66 (A) was being enforced. Before that it we all knew what size wire to run to a ground rod and there was never any argument about it.

That furthers my point that the code NEVER intended that anything larger than 6AWG be run to ground rods, and it doesn't matter if your on '17 code or not.
 
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