Grounding Electrode Conductor

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troywibb

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250.66(A) States that the portion of the conductor that is the sole connection to the grounding electrode conductor shall not be required to be larger than 6 AWG CU or 4 AWG AL wire.
Does this mean that the GEC attached to the service if not attached to anything else dosn't have to be sized with table 250.66? i.e; 400 AMP residential service with no other means of grounding except the ground rods.
 
The GEC to a ground rod is never required to be larger than a #6 regardless of the size of the service. A 2000-amp service would still require a #6 CU conductor. Just be aware that if a concrete encased electrode is PRESENT it must be used as part of the Grounding Electrode System. Your local AHJ or power supplier may have requirements as to HOW the GEC is installed. For example our power supplier does not allow the GEC to be intalled in a meter base.
 
troywibb, no matter how large the service is the largest conductor the NEC requires run to a ground rod is 6 AWG Copper or 4 AWG AL.

Put a 4000 amp service in the middle of nowhere and all you will need is a 6 AWG to one or two ground rods to meet the code.
 
I had to change my drawings to reflect a 2/0 GEC from a #6 even after I gave him the 250.66(A) reference to the AHJ. This is on a 1000A panel with only a ground rod driven. The Panel is fasten to a pedistal on a small concrete pad.
 
Bjenks said:
I had to change my drawings to reflect a 2/0 GEC from a #6 even after I gave him the 250.66(A) reference to the AHJ. This is on a 1000A panel with only a ground rod driven. The Panel is fasten to a pedistal on a small concrete pad.
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of what material is the pedistal constructed ??

and how is the pad made How deep etc???
 
iwire said:
troywibb, no matter how large the service is the largest conductor the NEC requires run to a ground rod is 6 AWG Copper or 4 AWG AL.
Click to expand...


I'm curious as to how you can get an AL conductor on a ground rod when they are not permitted within 18" of the earth. Maybe a 10' rod only installed 8.5'?
 
resistance different grounding electrode same Bldg

resistance different grounding electrode same Bldg

For two grounding electrode (Earth rod) installed for two LV different distribution panel
A=480V & B=208V, and they are 100 Meter a part of each other.

What is the resistance in ohms between them should be?
The perfect condition, as I remember is should be (1 ohm only)!
Please help!!
 
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