Size of GEC for ground rod

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enteng14

enteng14

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Manila, Philippines
Good day electrical experts..

I would like to inquire about the size of GEC when using ground rod as the sole grounding electrode connection to the earth.

What would be the size of grounded service conductor when using ground rod as the sole grounding electrode?

What if the ungrounded phase conductor is 5.5mm2 for single branch circuit, what would be the size of GEC and grounded service conductor for using ground rod as sole grounding electrode...

Thanks and good day!
 
Table 250.66. The GEC to a GR is not required to be larger than #6 unless subject to physical damage.
 
infinity said:
Table 250.66. The GEC to a GR is not required to be larger than #6 unless subject to physical damage.
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so if i have a service with parallel 500 mcm's all i need is a #6 awg GEC even if the only grounding electrode is 2 ground rods? i was asking myself this question and almost posted it! nice topic choice OP!
 
Table 250.66 is not applicable for GEC sizing for ground rod electrode. NEC 250.66 (A) discusses only that GEC isn't required to be larger than 6 AWG.

Is there no minimum size for GEC using ground rod electrode as sole connection?
 
enteng14 said:
Table 250.66 is not applicable for GEC sizing for ground rod electrode. NEC 250.66 (A) discusses only that GEC isn't required to be larger than 6 AWG.

Is there no minimum size for GEC using ground rod electrode as sole connection?
Click to expand...

Right, I should have added some more info to my original post
 
What about sizing of grounded service conductor when using ground rod electrode..

What would be the size of grounded service conductor and GEC when the ungrounded service entrance conductors is 3.5 sq mm (12 AWG) for single branch circuit installation?
 
enteng14 said:
Table 250.66 is not applicable for GEC sizing for ground rod electrode. NEC 250.66 (A) discusses only that GEC isn't required to be larger than 6 AWG.

Is there no minimum size for GEC using ground rod electrode as sole connection?
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The minimum size per 250.66 is 8 AWG, but it must be protected in conduit.
6 AWG does not require protection. I use 2 AWG but this is for exposed locations and its cad welded to an antenna mast that has a pivot point, the 2 AWG is less likely to be damaged
 
enteng14 said:
What about sizing of grounded service conductor when using ground rod electrode..

What would be the size of grounded service conductor and GEC when the ungrounded service entrance conductors is 3.5 sq mm (12 AWG) for single branch circuit installation?
Click to expand...


You lost me, if your only installing ground rods, then that portion of the GEC shall not be required to be larger than #6 cu.

If I ran a branch circuit to an outbuilding then a grounding electrode shall not be required. As long as the branch circuit that supplies that outbuilding has a equipment grounding conductor.
 
Sir stickyboy,

I am referring to a single branch circuit installation where there is limited load as stated in 230.79 (A) where the size of the service disconnecting means not less than 15 amperes.

I am still referring at the service. If the rating of the service equipment is 15 amperes and the grounding electrode use is only the ground rod and the size of ungrounded service entrance (hot) conductors is # 12 AWG (3.5 sq. mm). What would be the size of the GEC and the grounded service conductor considering that 250.66(A) only refer to the maximum size of GEC for ground rod electrode?

hope you understand what i mean sir.. this would be a great help.. thanks sir
 
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enteng14 said:
Sir stickyboy,

I am referring to a single branch circuit installation where there is limited load as stated in 230.79 (A) where the size of the service disconnecting means not less than 15 amperes.

I am still referring at the service. If the rating of the service equipment is 15 amperes and the grounding electrode use is only the ground rod and the size of ungrounded service entrance (hot) conductors is # 12 AWG (3.5 sq. mm). What would be the size of the GEC and the grounded service conductor considering that 250.66(A) only refer to the maximum size of GEC for ground rod electrode?

hope you understand what i mean sir.. this would be a great help.. thanks sir
Click to expand...


You would still use Table 250.66, the minimum size is #8 cu, but as stated above it would need to be protected.
 
stickboy1375 said:
You would still use Table 250.66, the minimum size is #8 cu, but as stated above it would need to be protected.
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Table 250.66 is not applicable for GEC sizing for ground rod electrode. NEC 250.66 (A) discusses only that GEC isn't required to be larger than 6 AWG.
 
enteng14 said:
Table 250.66 is not applicable for GEC sizing for ground rod electrode. NEC 250.66 (A) discusses only that GEC isn't required to be larger than 6 AWG.
Click to expand...

How do you figure its not applicable? 250.66 (A) just says its useless to use larger than #6...
 
stickboy1375 said:
How do you figure its not applicable? 250.66 (A) just says its useless to use larger than #6...
Click to expand...
you people are genius's. I was taught wrong in school over this! so this is the same as the ufer ground basically, larger than #4 not required?
 
stickboy1375 said:
How do you figure its not applicable? 250.66 (A) just says its useless to use larger than #6...
Click to expand...

How can it be applied if it is useless?

From Understanding the NEC volume 1 by mikeholt,
250.66 Grounding Electrode Conductor Size. Except for a ground rod electrode [250.66(A)]....the grounding electrode conductor must be based on the largest service entrance conductor or equivalent area for parallel conductors in accordance with Table 250.66.

What if you have a service entrance conductors size above 2/0, would you still use the table knowing that it is useless?
 
Again sir,

If the rating of the service equipment is 15 amperes and the grounding electrode use is ONLY the ground rod and the size of ungrounded service entrance (hot) conductors is # 12 AWG (3.5 sq. mm). What would be the size of the GEC and the grounded service conductor considering that 250.66(A) only refer to the maximum size of GEC for ground rod electrode?
 
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