Ground Ring versus Rod

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dwinchel

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Forth Worth, TX
Is there a code requirement to install a ground ring or rod's? This is related to an outdoor installation of a silo. I have an opportunity now to install a ring during the foundation excavation or rods at a later time. I am trying to determine a best practice (preference) or code requirements that I should be aware of. Thanks for the help.
 
augie47

augie47

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Location
Tennessee
Occupation
State Electrical Inspector (Retired)
A premises wiring system supplied by a grounded ac service is required to have a grounding electrode system. The permissible electrodes are listed in Art 250 part III. You may elect to use any of those listed. (You must also use all that are present)
If you foundation or footer has reinforcing steel per 250.52(A)(3) you are required to use that as an electrode.
Some POCOs require a ground rod regardless of the presence of other electrodes.
 
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dwinchel

Member
Location
Forth Worth, TX
Does that still apply when using a grid or rods to bond non-current carrying items to earth and ultimately back to a supply source? The premises wiring already has a grounding electrode system installed. Existing MCC's (480v) and panel boards (110v) providing power out to this area will have wiring installed correctly so there is an effective ground path to facilitate the operation of a overcurrent device.
 
augie47

augie47

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Tennessee
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State Electrical Inspector (Retired)
dwinchel said:
Does that still apply when using a grid or rods to bond non-current carrying items to earth and ultimately back to a supply source? .
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I may not fully understand that statement, but grid and rods can not serve as the ground path to operate OCP devices {See 250.4(B)(4)}.
If you have circuits from a premises to an "area" those circuits must alsio have a 250.118 recognized equipmet ground.
dwinchel said:
The premises wiring already has a grounding electrode system installed. Existing MCC's (480v) and panel boards (110v) providing power out to this area will have wiring installed correctly so there is an effective ground path to facilitate the operation of a overcurrent device.
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This may be a bit of a grey area (sight unseen). Can you provide more details as to what comprises this "area". You have to be careful based on the NEC's broad definition of a "building".
 
augie47

augie47

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Tennessee
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State Electrical Inspector (Retired)
jumper said:
True, but I never understood why. Rods seem to be the most worthless of all options regarding electrodes.
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Local POCO folks say they want it as it's the easiest for them to confirm.
90% of the E/Cs connect to the meter socket and often the top of the ground rod is exposed or easily exposed so for POCO its a quick check.
The State inspection process has no method to confirm the connection or presence of the CEE or if the water pipe is actually an electrode.
 
iMuse97

iMuse97

Senior Member
Location
Chicagoland
Because of the nature of a silo, and process movement within this structure, and many possible activities and processes in its general vicinity, the bonding of a grounding electrode system important. I would do what it takes to get a good ufer ground, and a ground ring, if possible. Bonding at all appropriate points will provide a safe installation and eliminate possible static capacitance as well.
 
RichB

RichB

Senior Member
Location
Tacoma, Wa
Occupation
Electrician/Electrical Inspector
We require a grouond ring, in addition to a Ufer and bonding wire, around all our high-mast lifgting, 100 feet tall, just as precaution to disapate static and help with any lightning strikes.
 
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