multiple ground rods conductor size

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dan55

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having an argument with a co-worker (six-pack bet on it) do you ever have to have larger than #6 to a ground rod even if there are multiple. I say no and can't find anything otherwise. Is there another ref. other than250.66. assuming this is the sole grounding means.
 
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dan55 said:
. . . do you ever have to have larger than #6 to a ground rod . . .
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The answer to the question the way it is asked is yes. However, the NEC never requires anything larger than a #6 Cu to a ground rod or multiple ground rods. Many engineers require larger than a #6 and also require more than a single ground rod (two if the resistance is more than 25Ω). Many engineers will require three ground rods in a triangular configuration, 20 feet long, and larger diameter than ?". :)
 
If the designer for some reason decided to go from the service equipment to a ground rod, and then from the ground rod to a concrete encased electrode, for example.

This would be a case where #6 awg would not be a sufficient size to run to the ground rod.

However, I assume you don't mean different types of electrodes and the configuration of the GEC.

Regardless of the service size, and regardless of the number of rod electrodes, #6 awg is all you will ever need.
 
per NEC only means of grounding was ground rod and you had to use two ground rods (25ohms) you would only required to use a #6 copper. right? no matter what the service size is.
 
You tell me...
250.53(E) Supplemental Electrode Bonding Connection Size.

Where the supplemental electrode is a rod, pipe, or plate electrode, that portion of the bonding jumper that is the sole connection to the supplemental grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.
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:smile:
 
I would say a #6 is all that is required. my employee seemed to think there was something somewhere else , but as far as I know that is the only reference there is . But I have been wrong before, and will be again.
 
dan55 said:
.... do you ever have to have larger than #6 to a ground rod....
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dan55 said:
. you would only required to use a #6 copper. right? no matter what the service size is.
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250.53(E) Supplemental Electrode Bonding Connection Size.

Where the supplemental electrode is a rod, pipe, or plate electrode, that portion of the bonding jumper that is the sole connection to the supplemental grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.
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It's a technicality :wink:
If it's AL...#4.

You guys may have to split the cost of the 6-pack :smile:
 
250.53(E) is for supplemental electrode bonding jumpers. I don't think that is what the OP was asking about. I think he was talking about the GEC to a pair of rods or the bonding jumper between them. In either case, the correct code section would be 250.66(A). Regardless, the wording is just about the same.

I have always interpreted this the way you all have responded... that #6 is all that is required. However, using Charlie's Rules and reading it again as if it was the very first time, I am wondering if that is what it really says. Consider the GEC running to the first rod which then has a bonding jumper running to the second rod. The GEC is not the sole connection to the first rod. There is also a bonding jumper connected to that rod. 250.66(A) only applies to that portion of the conductor that is the sole connection to the rod.

I'm not really planning on changing the way I'm enforcing this, but if there is a bet on the line...... ;)
 
Opps...250.66(A) should have been the correct reference..nice catch and TY. :smile:


eprice said:
Consider the GEC running to the first rod which then has a bonding jumper running to the second rod. The GEC is not the sole connection to the first rod. There is also a bonding jumper connected to that rod. 250.66(A) only applies to that portion of the conductor that is the sole connection to the rod.
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Where does the last sentence 250.58 come into play?
 
celtic said:
It's a technicality :wink:
If it's AL...#4.

You guys may have to split the cost of the 6-pack :smile:
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Who's gonna pay for the 9.5+' rods required for aluminum to be attached to the rods?
 
Speaking of ground rods....someone mentioned to me that rods only have an ampacity of "like 55A..that's why you only need a #6 wire".
 
celtic said:
Speaking of ground rods....someone mentioned to me that rods only have an ampacity of "like 55A..that's why you only need a #6 wire".
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The rod itself is certainly capable of more than that. It's the rod-to-earth contact and the earth itself that makes anything larger wasteful.
 
celtic said:
. . . rods only have an ampacity of "like 55A. . .
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You are sort of correct. If there is a medium or higher voltage fault for an extended period of time, the earth around a rod will become more non-conductive. I don't know that there is actually an amperage limitation placed on ground rods. For a low voltage ground fault, considering the low amount of current flow, this would be a non-issue. :)
 
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