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Old 10-28-2009, 06:56 AM   #1
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Ground size to panel


If you have a disco outside at the meter then the panel inside(main panel) should be treated as a sub (4 wire isolated neutral and ground) correct? It can be a mlo panel? If it is a 200amp service using 4/0AL individual conductors in conduit according to 250.66 you can use a #2AL for the ground is that correct? Thanks.

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Old 10-28-2009, 07:17 AM   #2
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Ground size to panel


Yes #2 al for your grounding conductor. #4 copper to your water line and 6 to your rod(s).
You don't need conduit. Just use SER.
NEC 08

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Old 10-28-2009, 09:02 PM   #3
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Ground size to panel


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Originally Posted by Penczak View Post
Yes #2 al for your grounding conductor. #4 copper to your water line and 6 to your rod(s).
You don't need conduit. Just use SER.
NEC 08
If you use #6 to the ground rods, you'll need to protect if from physical damage.

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Old 10-28-2009, 11:46 PM   #4
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Ground size to panel


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Originally Posted by busman View Post
If you use #6 to the ground rods, you'll need to protect if from physical damage.

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That must be a local thing because nowhere in the NEC is it required.
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Old 10-28-2009, 11:56 PM   #5
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Ground size to panel


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Originally Posted by Magnettica View Post
That must be a local thing because nowhere in the NEC is it required.
well, it is in the NEC but not quite that simple. I don't have my 08 handy but in the o5, try 250.64(B)
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Old 10-29-2009, 06:09 AM   #6
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Originally Posted by Magnettica View Post
That must be a local thing because nowhere in the NEC is it required.
Yes, 250.64(B).

Since it's usually impossible to run a GEC for a ground rod along the surface. It usually needs to leave the foundation to get to the rod (unless it's inside the foundation). At this point, it is not "run along the surface of the building construction" and it needs to be in conduit or cable armor.

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Old 10-29-2009, 06:56 AM   #7
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Ground size to panel


Quote:
Originally Posted by busman View Post
Yes, 250.64(B).

Since it's usually impossible to run a GEC for a ground rod along the surface. It usually needs to leave the foundation to get to the rod (unless it's inside the foundation). At this point, it is not "run along the surface of the building construction" and it needs to be in conduit or cable armor.

Mark
Mark, it seems you are contradicting yourself here.


250.64(B) Securing and Protection Against Physical Damage.
Where exposed, a grounding electrode conductor or its enclosure shall be securely fastened to the surface on which it is carried. A 4 AWG or larger copper or aluminum grounding electrode conductor shall be protected where exposed to physical damage. A 6 AWG grounding electrode conductor that is free from exposure to physical damage shall be permitted to be run along the surface of the building construction without metal covering or protection where it is securely fastened to the construction; otherwise, it shall be in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or cable armor. Grounding electrode conductors smaller than 6 AWG shall be in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or cable armor.
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Answers based on the 2008 & 2011 NEC.
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Old 10-29-2009, 07:34 AM   #8
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Ground size to panel


I believe busman either has a very picky inspection or inspector in his area or he is taking the intent to the extreme.

While he is correct in the strictest sense, I have never seen the EGC being required to be within conduit for the distance from where it leaves contact with the building to the point it attaches to the electrode.

BUT, and this is why I did not get specific in my answer, only pointed out that there is a requirement in the NEC to protect a #6 in some cases;

there are times a #6 is required to be in conduit which is in contrast to magnettica's statement.

In reality, an inspector could read that section and interpret it so tightly that if there is a possibility that a mower could throw a stick or stone and hit the EGC, it would need to be in conduit regardless of the fact it is tightly along the structure.


simply put; mag's statement, as written, was incorrect; busman's statement, as written, is 100% correct.
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Old 10-29-2009, 07:41 AM   #9
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Ground size to panel


When they are saying "along the surface" can't the #6 be run along the surface of the concrete foundation down into the ground?

I have #4 at the house & the pool cabana, both protected by conduit
It's cheap insurance against damage
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Old 10-29-2009, 11:59 AM   #10
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Ground size to panel


yes BUT:

Quote:
A 6 AWG grounding electrode conductor that is free from exposure to physical damage shall be permitted to be run along the surface of the building construction without metal covering or protection where it is securely fastened to the construction;
that can be interpreted that a rock from a mower or even the possibility that a animal can chew it could be construed that it is not free from exposure to physical damage.

In my area, there is no problem running the wire open as long as securely attached to the building and then buried to the point of connection.

I would accept that there are areas that are not as lenient.

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