Ground rod distance

[Mustwin351]

I dont have my code book in front of me but I dont recall any mention stating the distance a ground rod must be from it's panel or anything limiting the length of a grounding electrode conductor to a ground rod or grounding electrode. Is that in the NEC or something regulated by the authority having jurisdiction?

 

[Smart $]

No length limitation in the NEC as written. Have not heard of any AHJ limiting length.

 

[mopowr steve]

Are you sure that your AHJ isn't talking about the distance between two rods? If you have both installed.

 

[Dennis Alwon]

Here is the article mentioned above

250.53(A)(3) Supplemental Electrode. If multiple rod, pipe, or plate
electrodes are installed to meet the requirements of this
section, they shall not be less than 1.8 m (6 ft) apart.

 

[Mustwin351]

Here is the article mentioned above

No sir, I'm familiar with the 6' rule or more between rods just seemed odd that nothing is mentioned about how far from the panel they can or should be. Obviously the closer to the panel the better just figured there would be a mention of it.

 

[JFletcher]

No reason to limit the distance between rod and panel or GEC length. Job specs may be more restrictive than the NEC on distance between rod and panel (no NEC rule), rod to rod (>6'), and the # of them (sometimes 3).

 

[mopowr steve]

No sir, I'm familiar with the 6' rule or more between rods just seemed odd that nothing is mentioned about how far from the panel they can or should be. Obviously the closer to the panel the better just figured there would be a mention of it.

How could anyone know how close a rod could be placed to a panel when there would be a wide range of possibilities of where a panel is located and accessible ground to drive a rod into?

 

[Dennis Alwon]

No reason to limit the distance between rod and panel or GEC length. Job specs may be more restrictive than the NEC on distance between rod and panel (no NEC rule), rod to rod (>6'), and the # of them (sometimes 3).

I disagree. The closer to the panel the better because the grounding electrode conductor would have less impedance. The grounding electrode conductor should be as short as possible, IMO.

 

[jaggedben]

I disagree. The closer to the panel the better because the grounding electrode conductor would have less impedance. The grounding electrode conductor should be as short as possible, IMO.

For a rod (or two) the GEC would have to be tremendously long to have anywhere near the impedance of the electrode to earth contact itself. However I agree it should be as short a practicable. Other reasons for keeping it short and with minimal bends include limiting potential lighting side flash and also reducing the chances that it will get cut or removed in a location where its purpose isn't obvious.

 

[Galt]

What if you use bare copper ground wire? One hundred feet of wire plus a rod would surely be better than four feet and a rod.

 

[Smart $]

What if you use bare copper ground wire? One hundred feet of wire plus a rod would surely be better than four feet and a rod.

Only if the bare wire is buried below permanent moisture level.

 

[sparkcontrol]

What if you use bare copper ground wire? One hundred feet of wire plus a rod would surely be better than four feet and a rod.

On my job we are installing lamp pole bases , and the spec calls for a ground rod and #6 wire up the base to attach to the pole. It doesn't specify any particular depth below the surface. We are currently driving the rod so it's 2' below the surface as not to interfere with the conduit install. On another job others in my shop say it must be 2" below the surface. I searched thru the NEC book and found that if buried it allowed by exception. 250.68

Does anyone have any input on this?
Thanks

 

[romex jockey]

Take a look at the last sentence of 250.64 (B) >>>

Grounding elec-
trode conductors and grounding electrode bonding jumpers
shall not be required to comply with 300.5.

~RJ~

 

[Saturn_Europa]

On my job we are installing lamp pole bases , and the spec calls for a ground rod and #6 wire up the base to attach to the pole. It doesn't specify any particular depth below the surface. We are currently driving the rod so it's 2' below the surface as not to interfere with the conduit install. On another job others in my shop say it must be 2" below the surface. I searched thru the NEC book and found that if buried it allowed by exception. 250.68

Does anyone have any input on this?
Thanks

It sounds like an auxiliary grounding electrode. Which is covered under 250.54

 

[earlydean]

check out 800.100(4)
As short as practicable, not to exceed 20 feet.
This is for telephone system grounding, which is #14 copper.
Cable TV is in 820.100, same rule
Networks is in 830.100, same rule

Services have a requirement for larger conductor sizes to keep the impedance down on the longer runs. IMHO, it is best to keep the length as short as we can, reasonably. The grounding electrode conductor does carry electricity from lightning, after all.

 

[Dennis Alwon]

On my job we are installing lamp pole bases , and the spec calls for a ground rod and #6 wire up the base to attach to the pole. It doesn't specify any particular depth below the surface. We are currently driving the rod so it's 2' below the surface as not to interfere with the conduit install. On another job others in my shop say it must be 2" below the surface. I searched thru the NEC book and found that if buried it allowed by exception. 250.68

Does anyone have any input on this?
Thanks

It just needs to be below grade. In fact if you use a 10' rod it can actual stick up 2' because the code only requires 8' in the ground. Of course then you have to protect the wiring...

The reason it must be below ground is because the code requires 8' rod minimum in the earth. If you buy an 8' rod then it must be below grade. Nothing in the nec states how far it should be underground

 

[JFletcher]

I agree with Dennis in that it should be as short and straight as possible, but since that varies a fair amount per install, no defined number is possible.

check out 800.100(4)
As short as practicable, not to exceed 20 feet.
This is for telephone system grounding, which is #14 copper.
Cable TV is in 820.100, same rule
Networks is in 830.100, same rule

Services have a requirement for larger conductor sizes to keep the impedance down on the longer runs. IMHO, it is best to keep the length as short as we can, reasonably. The grounding electrode conductor does carry electricity from lightning, after all.

The GEC is not designed as lightning protection or dissipation. and article 800 installs, if that #14 wire has to go more than 20', you pound a communications ground rod (5' minimum length) at the NID and run #6 from that to the building's GES (for residential anyway). In other apps, you use the nearest qualifying grounding electrode per 250.52(A)

800.100(B)(3)(2) prohibits using a building's lightning protection/conductors as a grounding means for chapter 8 grounding. 800.53 specifies a minimum 6' distance from them (lightning conductors) as well

 

[earlydean]

I agree with Dennis in that it should be as short and straight as possible, but since that varies a fair amount per install, no defined number is possible.




The GEC is not designed as lightning protection or dissipation. and article 800 installs, if that #14 wire has to go more than 20', you pound a communications ground rod (5' minimum length) at the NID and run #6 from that to the building's GES (for residential anyway). In other apps, you use the nearest qualifying grounding electrode per 250.52(A)

800.100(B)(3)(2) prohibits using a building's lightning protection/conductors as a grounding means for chapter 8 grounding. 800.53 specifies a minimum 6' distance from them (lightning conductors) as well

and check out the informational note #1 to 250.4(A)(1)

 

[jaggedben]

and check out the informational note #1 to 250.4(A)(1)

I was trying to remember where that language was. Thanks.