Ufer grounding Min Requirements and GEC

[Wakeboardr122]

I understand that the minimum requirement a GEC for ground rods is a #6 because a ground rod cannot displace anymore electric than that of the #6 wire. So it got me thinking, what makes the minimum requirement of a Ufer GEC to be a #4 minimum. I would think it would go off the same theory, the amount of rebar displaced under the building is much more, but less conductive of that of a ground rod? Does anyone know how the code panel came up with this?

To my understanding is in within code compliance to run a #4 ufer, hit my ground rods (2- 6' or more apart) and then tap onto my 1/0 GEC from the water pipe to the first means of disconnect. Unfortunatly around here (Fort Lauderdale, Fl) I just failed inspection using a 1/0 ufer for 400A main service due to the fact the inspectors look at the plans and our engineers do not understand 250.66B (concrete encased electrode not required to be larger than #4) As far as I see it right now its just plain overkill, I'm I looking at this correctly? Thanks

 

[Dennis Alwon]

Yes you can use #6 to the 2 rods and then tie onto the 1/0. I am not sure I understand fully what you are asking. If the plans call for 1/0 then you have to use 1/0

 

[ActionDave]

If you have a ufer you don't need ground rods.

 

[Wakeboardr122]

Ufer Min requirements

Ufer Min requirements

So it got me thinking, what makes the minimum requirement of a Ufer GEC to be a #4 minimum. I would think it would go off the same theory, the amount of rebar displaced under the building is much more, but less conductive of that of a ground rod? Does anyone know how the code panel came up with this?

 

[Wakeboardr122]

If you have a ufer you don't need ground rods.

I guess that matters where you live, in my area we use all available during new construction. How about the reasoning there is a #4 min to the ufer?

 

[infinity]

#4 is the maximum size required GEC to a concrete encased electrode not the minimum. Also the #4 minimum is for when you make a CCC using a copper conductor, if you had the proper minimum size and length of rebar then you would not need to use the 20' of #4 copper to make the CEE. The GEC to the CEE is chosen from T250.66.

 

[Wakeboardr122]

Ufer #4 Max required

Ufer #4 Max required

Why is it that a Ufer only needs a #4 max. Without guessing can anyone show some numbers on this?

 

[iwire]

Why is it that a Ufer only needs a #4 max. Without guessing can anyone show some numbers on this?

I don't think you can get a firm answer but I would say it's the same reason the max size needed for a ground rod is 6 AWG.

You just can't make a connection to 'dirt' that is going to require more than these max sizes.

 

[infinity]

Since these two thread were closely related I've moved the other thread here.

 

[George Stolz]

If the plans call for 1/0 then you have to use 1/0.

That would depend on the local jurisdiction, no? I am always interested in seeing a legal mechanism that requires more than the code requires because an engineer graced the scene with his or her presence.

 

[iwire]

That would depend on the local jurisdiction, no? I am always interested in seeing a legal mechanism that requires more than the code requires because an engineer graced the scene with his or her presence.

In my area inspectors only inspect for code compliance but the argument is that once plans have been submitted and approved any deviation from those plans would require they go back to the building department to be approved again. There is a certain amount of logic in that.

 

[roger]

I guess that matters where you live, in my area we use all available during new construction.

So don't drive the rods, they won't be present or available.

Roger

 

[electricalist]

Grounds rods are a suplemental GEC which would be in addition to the cold water, creating a GES. When no water lines are avaliable a ground rod can suplement another ground rod to create a GES. A CEE is a GES by its self.
With 2 ground rods ,cold water and a ufer, you have what is called profit loss.


Sent from my SM-G360P using Tapatalk

 

[infinity]

Grounds rods are a suplemental GEC which would be in addition to the cold water, creating a GES. When no water lines are avaliable a ground rod can suplement another ground rod to create a GES. A CEE is a GES by its self.
With 2 ground rods ,cold water and a ufer, you have what is called profit loss.

Profit loss, I like that LOL. :lol:

 

[ritelec]

reasearching…….

200 amp service………(house)
was...
#4 to water
two ground rods with a #6

now..
Installed CEE #4
still #4 to water
two ground rods not needed (unless inspectors asking)

The question is, does the water system still get bonded the same way (size conductor)?

thank you.

 

[ActionDave]

The question is, does the water system still get bonded the same way (size conductor)?

thank you.

Yes.

 

[ritelec]

Yes.

Thank you

 

[ritelec]

Wondering…..

with this double #4 bonding, have the manufacturers been adding an additional larger lug to their neutral bar ?

 

[ritelec]

guessing not, and one of these are needed

 

[ActionDave]

Wondering…..

with this double #4 bonding, have the manufacturers been adding an additional larger lug to their neutral bar ?

Every buss bar I know of will take a 4AWG with out the need for an add-a-lug. Some of the old stuff wouldn't, but everything in the last thirty years will.