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Old 01-02-2013, 07:38 PM   #1
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wire gauge - three questions


Background: My building and safety electric engineer said I need to use 3 AWT copper wire to connect a 200 AMP load center to a 200 AMP meter pedestal 100 feet away.

First question: I shop around for prices and I see most places use the terminology 3/0 AWG. Does the /0 indicate that the wire is AWT?

Second question: Do all three wires (2 hot + neutral) need to be the same size? I'm pretty sure the answer is yes, but just checking to make sure the neutral also needs to be 3 AWT.

Third question: I plan to install a new ground rod at the load center that is separate from the ground rod at the meter pedestal. What gauge should a wire that leads into the ground for a 200 AMP load center be? 3 AWT as well?

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Old 01-02-2013, 07:55 PM   #2
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wire gauge - three questions


Three ought or 3/0 is used to indicate a conductor size. A 3/0 and a #3 are two different sizes of conductor. It has nothing to do with the insulation type.

I think you might mean AWG which stands for American Wire Gauge, not AWT.

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Old 01-02-2013, 08:11 PM   #3
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wire gauge - three questions


I think he means ought.
3/0 wire is used for 200 amps in a non residential setting
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Old 01-02-2013, 08:14 PM   #4
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wire gauge - three questions


I think in this case AWT = ought. Got a chuckle out of that one
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Old 01-02-2013, 08:48 PM   #5
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wire gauge - three questions


Quote:
Originally Posted by jackwashere View Post
Background: My building and safety electric engineer said I need to use 3 AWT copper wire to connect a 200 AMP load center to a 200 AMP meter pedestal 100 feet away.

First question: I shop around for prices and I see most places use the terminology 3/0 AWG. Does the /0 indicate that the wire is AWT?

Second question: Do all three wires (2 hot + neutral) need to be the same size? I'm pretty sure the answer is yes, but just checking to make sure the neutral also needs to be 3 AWT.

Third question: I plan to install a new ground rod at the load center that is separate from the ground rod at the meter pedestal. What gauge should a wire that leads into the ground for a 200 AMP load center be? 3 AWT as well?
I am assuming your engineer friend is giving you advice about getting electrical service your own personal home?

You mention a pedestal .. is their a main disconnect associated with the meter pedestal or just a meter enclosure ? ... I'm asking because it is important to understand what will be your service equipment.

If the engineer said 3 awg copper you need to stop listening to him ... if he said 3/0 awg copper then he actually might be an engineer you should listen to...
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Old 01-02-2013, 08:53 PM   #6
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wire gauge - three questions


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Originally Posted by stubie View Post
If the engineer said 3 awg copper you need to stop listening to him ...
I was pretty clear about what the engineer said: 3 AWT (pronounced ought).

Internet searches for "3 AWT" lead me to lots of 3/0 AWG products. That's where the confusion occurs. I'm clear as to what the engineer said.
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Old 01-02-2013, 09:06 PM   #7
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wire gauge - three questions


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Originally Posted by jackwashere View Post
Internet searches for "3 AWT" lead me to lots of 3/0 AWG products. That's where the confusion occurs. I'm clear as to what the engineer said.
Well, the spelling is "aught", which is an old synonym for zero. Once upon a time 3-aught was written as 000, 4-aught was written as 0000, and so on. So yes, 3/0 is "three-aught". Which, as another poster said, is not the same thing as #3 -- 3/0 is larger.

AWG is an abbreviation for American Wire Gauge, which is the system used in North America for denoting wire sizes up to a certain point. Conductors larger than 4/0 are usually denoted in another units system called "circular mils".
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Old 01-02-2013, 09:07 PM   #8
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wire gauge - three questions


Quote:
Originally Posted by jackwashere View Post
I was pretty clear about what the engineer said: 3 AWT (pronounced ought).

Internet searches for "3 AWT" lead me to lots of 3/0 AWG products. That's where the confusion occurs. I'm clear as to what the engineer said.


Ok....that is funny.....lets chaulk this one up to "Lost in translation"....

When you say, "3/0".....it sounds like "Three Aught".....

If it's 2/0.....it's pronounced "Two Aught"...

Back on topic....I think 3 "AWT" is a bit small....I have a 200A feed and I'm using 2/0 (Or "Two AWT") wire.
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Old 01-02-2013, 09:44 PM   #9
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wire gauge - three questions


3/0 is larger than 2/0.
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Old 01-02-2013, 10:14 PM   #10
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wire gauge - three questions


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Originally Posted by Jim Port View Post
3/0 is larger than 2/0.
Yea....I knew that.......(can we say brain fart on my part?)

Is it too late to change "too small" to "too large"?




I hate it when I make stupid mistakes like that.....

And...Jim....the thanks is for pointing out my brain fart....and not roasting me for it....
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Old 01-02-2013, 10:21 PM   #11
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wire gauge - three questions


Quote:
Originally Posted by jackwashere View Post
I was pretty clear about what the engineer said: 3 AWT (pronounced ought).
It's 3/0 the zero is your "ought"
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Old 01-02-2013, 10:26 PM   #12
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wire gauge - three questions


Quote:
Originally Posted by jackwashere View Post
Background: My building and safety electric engineer said I need to use 3 AWT copper wire to connect a 200 AMP load center to a 200 AMP meter pedestal 100 feet away.

First question: I shop around for prices and I see most places use the terminology 3/0 AWG. Does the /0 indicate that the wire is AWT?
"AWT" = aught = the number zero = wire size larger than 0 AWG. This one's beaten to death so I'll stop there.

Quote:
Second question: Do all three wires (2 hot + neutral) need to be the same size? I'm pretty sure the answer is yes, but just checking to make sure the neutral also needs to be 3 AWT.
Yes, both hots and the neutral must be the same size. If there is a disconnect at the meter, then you need a fourth conductor (grounding) and it can be smaller. Whether you need 3/0 conductors or could get by with 2/0 for all of them is an open question. Whether you should be using copper versus aluminum is also questionable. I would use aluminum.

Quote:
Third question: I plan to install a new ground rod at the load center that is separate from the ground rod at the meter pedestal. What gauge should a wire that leads into the ground for a 200 AMP load center be? 3 AWT as well?
You need to install two ground rods at the panel (one if you prove the resistance is under 25 ohms, but don't bother trying - just install two). You also need to bond the building's water service, and connect to the rebar in the slab if there is any. Your grounding electrode conductor needs to be #4 copper, green or bare (no re-marking), running uninterrupted from the panel to the first rod.

If there is a disconnect at the pedestal, then you MUST run four conductors to the panel, and use separate neutral and ground bars in the panel, with the neutral bar isolated. If there is no disconnect at the pedestal, then you run three wires to the panel, and bond neutral and ground in the panel.
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Old 01-02-2013, 10:45 PM   #13
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wire gauge - three questions


Quote:
Originally Posted by jackwashere View Post
I was pretty clear about what the engineer said: 3 AWT (pronounced ought).

Internet searches for "3 AWT" lead me to lots of 3/0 AWG products. That's where the confusion occurs. I'm clear as to what the engineer said.
.... where is your service equipment panel ... the pedestal or the 200 amp panel at the home? Once you can tell us that then read post #12 by mpoulton

Last edited by Stubbie; 01-03-2013 at 12:01 AM.
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Old 01-03-2013, 07:47 AM   #14
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wire gauge - three questions


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Originally Posted by mpoulton View Post
"AWT" = aught = the number zero = wire size larger than 0 AWG. This one's beaten to death so I'll stop there.

You need to install two ground rods at the panel (one if you prove the resistance is under 25 ohms, but don't bother trying - just install two). You also need to bond the building's water service, and connect to the rebar in the slab if there is any. Your grounding electrode conductor needs to be #4 copper, green or bare (no re-marking), running uninterrupted from the panel to the first rod..
Would it be advisable to avoid writing down the term "AWT" and instead use the terminology 3/0. To avoid any confusion with American Wire Gauge.

Are you sure that we need #4 copper to the ground rods? Strangely, we need #4 copper to the water pipe (if metal leaving the house underground) for the 200 amp service but no fatter than #6 copper to ground rods. Then we would need the #4 grounding electrode conductor running nonstop from the panel to the pipe, and the #6 GEC from the rods to either the panel or to the #4 GEC whichever it reached first.
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Old 01-03-2013, 08:31 AM   #15
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wire gauge - three questions


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Originally Posted by AllanJ View Post
Would it be advisable to avoid writing down the term "AWT" and instead use the terminology 3/0. To avoid any confusion with American Wire Gauge.

Are you sure that we need #4 copper to the ground rods? Strangely, we need #4 copper to the water pipe (if metal leaving the house underground) for the 200 amp service but no fatter than #6 copper to ground rods. Then we would need the #4 grounding electrode conductor running nonstop from the panel to the pipe, and the #6 GEC from the rods to either the panel or to the #4 GEC whichever it reached first.
Those are code minimums though it is correct to make point of it. Even though #6 is all that is required to ground rods many, many ground rods for residences are connected with #4 GEC.

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