gr / Ground Rod

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bearchri

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Combined Joint Operations Area, Afghanistan
My job is at risk over this one--I am the electrical supervisor at an American Army base in Afghanistan. We are subject to NEC 2008, no local codes or regs.

Power is supplied by gen sets, feeding out to I-Line panels and then on to QO 100 and 225 amp panels. Typical building has one I-Line feeding subpanels on the building.

When the Army built the base, they installed one 3 meter segmented ground rod connected to the panel neutral bus by metric 6 AWG equivalent wire at each panel.

When I arrived last winter, I installed an isolated ground bar in each panel and an additional grounding electrode (8 ft rod) at each panel in one of 2 ways:

1--New 6 AWG wire from the ground bar to the new rod. Also relocated the existing ground wire to the new ground bar, thus each panel has more than one grounding electrode conductor and grounding electrode.

2--New 6 AWG wire from the ground bar to and through an acorn clamp on the old rod, then on to the new rod without splices.

I also interconnected all the electrodes on each structure. Sometimes this was by an underground conductor from one panel's rod to another panel's and sometimes it was from one panel's ground bar to the other panel's ground bar.

Today Quality Control reported that I am out of compliance with 250.64(C) because I have created a splice (the ground bar) between electrodes. I am also out of compliance with 250.56 because there are a couple of places the Army had installed more than one ground rod by running one section of wire from the panel to the rod, then a DIFFERENT section of wire from the first rod to the second rod. He also reported that I need to pull the rods up a little, as the connection is not accessible.

He is older and more experienced than me (maybe not saying much as I am 29) but I am not ready to say I am wrong yet. Any comments, especially code references? Can I run more than one GEC to a ground bar? Can I have a splice in rods in series? How do I get 8 ft of rod in contact with soil (250.53G) and have some of it out of the ground?

Thanks!
 
You are not wrong. (from what I think I am reading).

Below are a couple of illustrations that would apply

1100203955_2.jpg


and

1100202225_2.jpg


After the correct size GEC is run to the first electrode everything else are jumpers and tyeing more than one GES to another may be overkill but there is no requirement that it must an unbroken conductor.

On another note, the connection to the rod doesn't have to be accessible

Roger
 
Bearchri,.. I have a question or two.. were those neutrals re grounded at the sub panels??

it sounds as if there is no equipment grounding conductor run with the feeders??

What was the purpose of adding the electrodes ,.. are you trying to mitigate stray current??

If the neutral is serving as both grounded and grounding conductor driving rods will do very little.

Thanks for being there,.. keep safe and come home ..
 
same question from your post as M.D,=. is there an equipment fround from your I line to your sub-panels ?

and same commet as others "take care and stay safe"
 
bearchri said:
He also reported that I need to pull the rods up a little, as the connection is not accessible......

......How do I get 8 ft of rod in contact with soil (250.53G) and have some of it out of the ground?

Thanks!
Click to expand...

Not necessary to have the GEC connection out of the ground - 250.68(A), exception 1
 
HotConductor said:
. . . It's a little extra work but it makes a nice job even better.
Click to expand...
How do you comply with 250.53(G) Rod and Pipe Electrodes. The electrode shall be installed such that at least 2.44 m (8 ft) of length is in contact with the soil. . . ? You are losing almost 10% of the length of the rod in contact with the soil (sand in this case). :smile:
 
charlie said:
How do you comply with 250.53(G) Rod and Pipe Electrodes. The electrode shall be installed such that at least 2.44 m (8 ft) of length is in contact with the soil. . . ? You are losing almost 10% of the length of the rod in contact with the soil (sand in this case). :smile:
Click to expand...
Two ways- either drive it close to the bottom of the valve box or use a 10' rod.
 
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