# Ufer Ground



## John T

What size ufer ground for a 1200 amp service. the service conductors from the transformer to the building is 3 sets of 600 mcm.


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## 220/221

100 amp to 100,000 amps, a ufer is a ufer is a ufer.

#4



Right?


Metallic piping/building steel bond size goes up with the service amperage but the ufer stays the same.

Right?


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## BuzzKill

250.52(a)(3) '05 nec
250.66 for GEC


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## John T

the way i see it is 1/0 ground


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## Old Spark

According to FPN 250-24 the size for the ufer ground is determined by the size of the largest ungrounded service entrance conductor. For parallel conductor you use the take the size if you had one conductor. For the 1200 amp service it is unnecessary to add them all together because once you reach 1100 kcmil the ufer is 3/0 copper or 250 aluminum. No ground is required to be larger than 3/0 for an A/C system. I know everybody will jump on me and quote code that says a #4 is the largest size needed for a ufer ground, but here in my part of Ca. they use the code above and enforce it strictly. The easy way to find the sizes is to use an UGLY'S. The 2005 has the chart for A/C Systems on page 110 and on page 109 is the sizes for grounding equipment. There is a big difference between grounding equipment wire sizes and grounding A/C system sizes in these charts.
David


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## Dennis Alwon

John T said:


> the way i see it is 1/0 ground


Well you see it incorrectly. A ufer only needs to be #4 although you can use any size you want larger than #4. Same with a ground rod-- #6 is the largest conductor you would need.

250.66 has nothing to do with this-- 250.52(C) will show you the exception (so to speak) for ufers and 250.53(E) will show you for the ground rod.


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## brian john

David Channell said:


> According to FPN 250-24 the size for the ufer ground is determined by the size of the largest ungrounded service entrance conductor. For parallel conductor you use the take the size if you had one conductor. For the 1200 amp service it is unnecessary to add them all together because once you reach 1100 kcmil the ufer is 3/0 copper or 250 aluminum. No ground is required to be larger than 3/0 for an A/C system. I know everybody will jump on me and quote code that says a #4 is the largest size needed for a ufer ground, but here in my part of Ca. they use the code above and enforce it strictly. The easy way to find the sizes is to use an UGLY'S. The 2005 has the chart for A/C Systems on page 110 and on page 109 is the sizes for grounding equipment. There is a big difference between grounding equipment wire sizes and grounding A/C system sizes in these charts.
> David


 
FPN --What? Please show or tell me where this is stated in the FPN?


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## Old Spark

I am reading everything the NEC says about ufer grounding and it say's exactly what you said it says. I don't know why here in Ca. we have to use the table 250.66 unless the ahj has decided that they don't agree and will use the table. It's not clear to me what the table is for. All the systems that we have installed over the last 25 years would meet the NEC if we used the size 6. We have been allowed to use size 4 copper in residential but not commercial. I've just retired, but I'm going to try to find out why. Califonia does have it's own electrical code book, but I don't have one. I've been told that it is being discontinued.
David


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## Dennis Alwon

David Channell said:


> It's not clear to me what the table is for.
> David


Table 250.66 is for grounding electrode conductors. Thus the water pipe, building steel, ground rings, etc must be sized to this table. 

The ufer and the rods hsve an exception since the rod is no better than a #6 anyway. I assume the same for the ufer and a #4. 

Often times the specs will call for a larger wire-- I believe this is because of ignorance.


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## Old Spark

You are right. The plans do call out the ufer size here which is always based on the table. So our ufer is usually 20' of bare copper sized #2 for 200 amps, #1/0 for 400 amps and so on. Everybody must be using UGLY'S Electrical References page 110 instead of a code book.
David


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## Dennis Alwon

David Channell said:


> You are right. The plans do call out the ufer size here which is always based on the table. So our ufer is usually 20' of bare copper sized #2 for 200 amps, #1/0 for 400 amps and so on. Everybody must be using UGLY'S Electrical References page 110 instead of a code book.
> David


So why would they use #2 copper for a 200 amp service. These can be installed with 3/0 copper which is a #4 copper GEC by T. 250.66


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## brian john

Dennis Alwon said:


> So why would they use #2 copper for a 200 amp service. These can be installed with 3/0 copper which is a #4 copper GEC by T. 250.66


have run into this with inspectors and engineers. It comes from a misunderstanding of the code and their belief that they KNOW better than everyone else.

Same with people that argue about how circuit breakers work.
The purpose of a ground rod
And using a megger.

They have a belief in their head that they have lived with and taught others, to admit they were wrong now throws their WHOLE career in a bad light.

Me before I post I typically verify what I speak of, I seldom post NEC answers as there are others that are way better versed in the NEC than I ever will be. BUT I have been wrong before and will be again, probably wrong in the above statements somewhere.


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## Dennis Alwon

brian john said:


> have run into this with inspectors and engineers. It comes from a misunderstanding of the code and their belief that they KNOW better than everyone else.


Perhaps they are calling for 4/0 copper for a 200 amp service. That would make the GEC #2 but who knows why they would do that. 

Or it is exactly as you say they don't know any better or think they know it all.


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## Old Spark

*Ufer questions*



Dennis Alwon said:


> So why would they use #2 copper for a 200 amp service. These can be installed with 3/0 copper which is a #4 copper GEC by T. 250.66


 
You are absolutely right. I believe it is for 225 amp service we use #2 not 200 amp service.
David


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## JayH

David Channell said:


> I am reading everything the NEC says about ufer grounding and it say's exactly what you said it says. I don't know why here in Ca. we have to use the table 250.66 unless the ahj has decided that they don't agree and will use the table. It's not clear to me what the table is for. All the systems that we have installed over the last 25 years would meet the NEC if we used the size 6. We have been allowed to use size 4 copper in residential but not commercial. I've just retired, but I'm going to try to find out why. Califonia does have it's own electrical code book, but I don't have one. I've been told that it is being discontinued.
> David


David here is a link to an online CEC:

http://bulk.resource.org/bsc.ca.gov/title24_part03.pdf

CEC does not require any change in UFER sizing from NEC.

That being said, _*every*_ project I encounter sizes and specs the UFER per 250.66, maybe because engineers may not know any better. Or it may be simply that all I do is government work and they always overbuild.


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## RIVETER

*Ufer ground*



John T said:


> What size ufer ground for a 1200 amp service. the service conductors from the transformer to the building is 3 sets of 600 mcm.


 As far as I know I have not installed a Ufer ground. Are you asking what size Grounding Electrode Conductor you should run ...to be connected to the UFER?


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## Old Spark

Thanks Jay! I wish the engineers for commercial would go by N.E.C. instead of the table 250.66. Not only does it cost a lot more to install the large copper wire, the thieves love to steel the copper either before the concrete is poured or steal the 5' or 6' we leave out to attach to the MSB after concrete is poured.
David


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## JayH

I always install my UFER at the latest possible moment, usually the day of the pour.

If the inspector is unavilable I photograph the length of the UFER with a tape measurer showing length layed out next to the UFER.

After installation I try to conceal it by sleeving it with a 1" PVC conduit. I throw a couple of boxes on top of the conduit to make it look like debris.

Sometimes it works, sometimes not. If it doesn't work, I don't cadweld in the stub until the building is secure.


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## Old Spark

Yes, we started doing the sleeving after losing two ufers. Problem was they must have gotten it before the pad was poured for the msb, because there was no stub. Don't know how much they got because the footing was poured ahead and no one noticed the missing ufer until msb set.
David


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## brian john

On the positive side if everyone is over sizing their GEC's it is not detrimental, only costly for the end user.

But one would expect their AHJ's and engineers to know the NEC if they are enforcing/designing electrical systems.


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## manchestersparky

I met an EC who installs the uffer in the footer and gets it inspected prior to the footer being poured. What he does when they pour the slab is clever. He builds a wood box about 12x12 out of 2x4's, puts plywood on one side. THen he rolls up his uffer tail and puts the box over it and has them pour right over it. At a later date he just taps the floor to break the concrete that is over the box, like you would for a floor box. Then he just breaks out the wood and patches the floor.


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## JayH

manchestersparky said:


> I met an EC who installs the uffer in the footer and gets it inspected prior to the footer being poured. What he does when they pour the slab is clever. He builds a wood box about 12x12 out of 2x4's, puts plywood on one side. THen he rolls up his uffer tail and puts the box over it and has them pour right over it. At a later date he just taps the floor to break the concrete that is over the box, like you would for a floor box. Then he just breaks out the wood and patches the floor.


 
Smart man.


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## JohnJ0906

manchestersparky said:


> I met an EC who installs the uffer in the footer and gets it inspected prior to the footer being poured. What he does when they pour the slab is clever. He builds a wood box about 12x12 out of 2x4's, puts plywood on one side. THen he rolls up his uffer tail and puts the box over it and has them pour right over it. At a later date he just taps the floor to break the concrete that is over the box, like you would for a floor box. Then he just breaks out the wood and patches the floor.


That is a damn good idea.


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## Dennis Alwon

JayH said:


> Smart man.


I just bury mine in the dirt a few inches.


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## Old Spark

Here we have to place them in the bottom of the footing and hang it on the re-bar or if in a separate trench, it must be at least 12" deep and the ufer must be held up 3" above the dirt and have at least 3" of concrete below and on both sides and above. If we don't get it inspected, we had better take good pix and have a good relationship with the inspector.


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