Considering the connection between the 2 ground rods to be a bond and would be sized per 250.66. Sorry for the Article mistake.
Area controversy around sizing of GEC for ground rod
- Thread starter wbalsam1
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
We understand that oregon has come up with this but it is not an NEC rule. If you loop the wire then a #6 is all that is needed to a rod.
Why 4#? Assuming CU. Sole connection, right?
250.66(A) Connections to Rod, Pipe, or Plate Electrodes.
Where the grounding electrode conductor is connected to
rod, pipe, or plate electrodes as permitted in 250.52(A)(5)
or (A)(7), that portion of the conductor that is the sole connection
to the grounding electrode shall not be required to be
larger than 6 AWG copper wire or 4 AWG aluminum wire.
Where there getting this is the first three words of 250.66a,connections to ROD,not RODS. So if you are running a single GEC from the MDP to your grounding electrode yes the # 6 applies but if you run it through the acorn clamp at the first rod and then to the second rod,# 4 would be required. So again either seperate # 6 to each individual rods or a single # 4 for 2 RODS.
- Location
- Massachusetts
I have to agree with this.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
So if it a 400 amp service then what size does it need???? Let me clarify. If I have a 400 amp service with 2 rods looped with one GEC do they require a #2 or 1/0 to the rods. I am sorry I cannot accept this thinking. You may be right but I don't see it.
Last edited:
- Location
- New Jersey
- Occupation
- Journeyman Electrician
This is incorrect.
- Location
- Massachusetts
IMO you would need separate 6 AWGs to each rod or a 'full size' GEC to both rods.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I disagree. It doesn't make much sense, worse case scenario, to run a 3/0 to loop two rods.
It is almost like saying if I loop to 2 different CEE I would be allowed to loop the #4. The CEE is going to have a much lower resistance then two rods in almost all cases and it never needs to be larger than #4.
Another example I have a CEE #4 and I loop it to a ground rod then to the meter. The service is 400 amps. What size do I need? I see the words I just don't think that is what is meant. I have not heard of that interpretation anywhere before either. Logic tells me that isn't correct. I can see where the wording needs improvement. IMO, if they wanted a #4 in that case then it should be spelled out.
- Location
- Massachusetts
What has that got to do with anything?:grin:
Is it your position that I could have 100 rods and connect them all with one 6 AWG to the service?
To me that is like saying if 14 AWG is enough for one particular load it is also enough for two or more of that same load.
Each rod you add increases the current that could be expected to be carried on that GEC.
If the NEC decided it takes at least a 6 AWG for one rod IMO it must take more than a 6 AWG for two rods.
And please forget about how it is done and enforced and concentrate on the words and the application,
There is no 's' after the word electrode, that means one electrode not two, not three not ten.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
One could argue that a single rod is not an electrode since it's resistance is greater than 25 ohms (the reason you would be using two rods). The two rods together would then qualify as the electrode when used in together.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
That's a valid point but not pertinent.
Once we get a resistance of 25 ohms the NEC does not care. If I get 25 ohms with one rod then I don't need another but if I do add another then I cannot loop a #6 to both rods. IMO, if resistance was the reason for #6 to a single ground rod then the NEC has it all wrong.
You know as well as I that you would need less than 6 ohms from a rod to carry fault current. That is not it's purpose-- I know you know this. If lightning strikes I doubt that 2 rods will make a difference. If resistance were the issue then why not require a #4 to a rod that gets 5 ohms?
If a services requires a 3/0 copper and I decide to loop my gec to the rods do you think a 3/0 is equivalent to 2- #6 each going separately to a rod.
I understand where the OP is getting the info.
jxofaltrds
Inspector Mike®
- Location
- Mike P. Columbus Ohio
- Occupation
- ESI, PI, RBO
#6 is all that is required.
There is only "one" ground rod present at any installation. Others (250.56) augment the original rod. #6 is all that is needed to bond to the 'first' ground rod.
EDIT forgot to say look at the "s" on electrodes at the end of the first sentence.
Last edited:
- Location
- Massachusetts
I don't think that is a successful argument
250.56 tells us that a single rod with more than 25 ohms is an electrode.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Hey I tried. :roll:
- Location
- Massachusetts
IMO none of the requirements in 250.56 are pertinent to this discussion or influence the requirements found in 250.66.
I do not know any of that and neither does anyone here.
But we can read the requirement in Charlie's way.
Has nothing to do with what 250.66(A) says.
What I think is a single 3/0 to both rods or two independent 6 AWGs will meet the requirements of the NEC.
I also think that a singe 6 AWG to more than one electrode for a service that normally requires 3/0 is a code volition.
- Location
- Massachusetts
Look at my reply to Rob.
That 's' has to do with the fact they are talking about rods, pipes and plate electrodes.
Once you get into the meat of the section it is singular.
Absolutely, how do we even know that these 100 rods have gotten us below 25 ohms? There is no requirement to test them so they are not really significant as far as needing to provide a larger jumper for any practicle purpose.
But there is a very good probability that it will not need to carry more current than the maximum 25 ohm value would equate to and we know that only requires a #6
Roger
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
A quick search came up with this:
By sole connection it is meant that it is not a part of a grounding electrode system where other type electrodes requiring grounding electrode conductors larger than 4 AWG would be affected by a smaller size conductor being used to bond the electrodes together.
From here:http://www.neca-neis.org/cqd/index.cfm?fuseaction=showArchiveQuestion&id=2620
Although it addresses a question on 250.66(B) on a CEE, would not the same principle apply to 250.66(A) and rods with #6?
By sole connection it is meant that it is not a part of a grounding electrode system where other type electrodes requiring grounding electrode conductors larger than 4 AWG would be affected by a smaller size conductor being used to bond the electrodes together.
From here:http://www.neca-neis.org/cqd/index.cfm?fuseaction=showArchiveQuestion&id=2620
Although it addresses a question on 250.66(B) on a CEE, would not the same principle apply to 250.66(A) and rods with #6?
- Location
- Massachusetts
I agree with you 100%, none the less I feel it is what the wording requires.
I agree with that as well.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
You are using Charlie's rule but I read the rule differently then you do.
It does not say where the gec is connected to A Rod, A Pipe, or A Plate electrode it says what it says....:grin: Where the GEC is connected to a rod, pipe, or plate electrodes
So now you can install 3/0 or a #6 to each rod but I think I will read it the way it looks to me as well as, I believe, most of the electrical community.
Perhaps the wording needs work so I will propose to the CMP a change in wording and see what they say.
It does not say where the gec is connected to A Rod, A Pipe, or A Plate electrode it says what it says....:grin: Where the GEC is connected to a rod, pipe, or plate electrodes
So now you can install 3/0 or a #6 to each rod but I think I will read it the way it looks to me as well as, I believe, most of the electrical community.
Perhaps the wording needs work so I will propose to the CMP a change in wording and see what they say.
- Status