# Confused



## BBQ (Nov 16, 2010)

Wow, I understand article 250 fine but I do not understand what you are asking at all. :blink:


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## drspec (Sep 29, 2012)




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## Dengarrett (May 6, 2013)

I'm just trying to understand from the code the reasoning for #4 to the water pipe and #6 to the rods.


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## 480sparky (Sep 20, 2007)

Dengarrett said:


> I'm just trying to understand from the code the reasoning for #4 to the water pipe and #6 to the rods.


Driven rods can only carry so much current. Any wire size larger would simply be a waste.


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## KGN742003 (Apr 23, 2012)

> So it seems that if I did exactly what the code says, I run a #4 to the water pipe for bonding, and then run another #6 to the water pipe as the GEC. But given the GEC would not be the only wire connected, it must also be #4. So then I have two #4's running from the same place to the same place??? Or would it just be that #4 is used to jump the meter only, and then #6 runs to the service? Argh!!!


When the water pipes are part of the grounding electrode system then the bonding is inherent. If you have some sort of non-metallic pipe coming in and metal pipe in the house, then the metal pipe has to be bonded.


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## Dengarrett (May 6, 2013)

480sparky said:


> Driven rods can only carry so much current. Any wire size larger would simply be a waste.


Ah right.



KGN742003 said:


> When the water pipes are part of the grounding electrode system then the bonding is inherent. If you have some sort of non-metallic pipe coming in and metal pipe in the house, then the metal pipe has to be bonded.


Thanks I was on that same track and almost followed up to my post when I saw yours.


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## ponyboy (Nov 18, 2012)

All that grounding and bonding nonsense is pure voodoo. Around here we just throw some copper at it, make it big, and leave it alone. Most inspectors probably just pretend they know what they're looking for anyway. Hehe


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## Dengarrett (May 6, 2013)

480sparky said:


> Driven rods can only carry so much current. Any wire size larger would simply be a waste.


Because of some difference between pipe and rod other than required length of contact to ground per 250.52(a)(1) and 250.52(a)(5)?


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## Dengarrett (May 6, 2013)

KGN742003 said:


> When the water pipes are part of the grounding electrode system then the bonding is inherent. If you have some sort of non-metallic pipe coming in and metal pipe in the house, then the metal pipe has to be bonded.


This makes obvious sense to me, but does it say it somewhere in the code?

Edit - I mean the part about bonding being inherent. Or maybe it's just that it IS bonded if it is in the GE system. Yeah sorry - answered my own question.


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## BBQ (Nov 16, 2010)

Dengarrett said:


> Because of some difference between pipe and rod other than required length of contact to ground per 250.52(a)(1) and 250.52(a)(5)?


A rod is only so big, it has a maximum area of 'dirt' it is in contact with and even with a highly conductive soil there is only so much current that the conductor going to the rod is going to be subjected to. The connection between the rod and the earth will be the limiting factor.

Now, get to w water line, in the old days of metal water systems the water line could be in contact with the earth for miles and this would lower the resistance between the earth as a whole and the pipe.

_BUT,_ that is not the biggie, the biggie is that in a metal water piping system the water line would be bonded to the utility neutral in everyone's home making a much lower resistance back to the source meaning much higher currents could be put on the grounding electrode conductor to the water line.


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## Celtic (Nov 19, 2007)

I had read somewhere that a ground rod was capable of carrying 65A


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## BBQ (Nov 16, 2010)

Dengarrett said:


> This makes obvious sense to me, but does it say it somewhere in the code?


Not in those words, the code puts it more like this.

If there is a metal water supply that qualifies as an electrode 250.52(A)(1) we must use it. 250.50


If there is a metal water piping system we must bond it. 250.104(A)


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## BBQ (Nov 16, 2010)

Celtic said:


> I had read somewhere that a ground rod was capable of carrying 65A


You know that is depends on the voltage and soil conditions.


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## Dengarrett (May 6, 2013)

BBQ said:


> in a metal water piping system the water line would be bonded to the utility neutral in everyone's home making a much lower resistance back to the source meaning much higher currents could be put on the grounding electrode conductor to the water line.


Ahhhh of course. The lowest resistance pathways just are not always obvious.


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## Celtic (Nov 19, 2007)

BBQ said:


> You know that is depends on the voltage and soil conditions.


Very true.

I was unable to find the article I read to even substantiate my comment :001_unsure:

...but....

It is of interest to mention that a #6 Cu THHW conductor has a 65A rating as well [Table 310.15(B)(16) (formerly Table 310.16)]


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## BBQ (Nov 16, 2010)

Celtic said:


> It is of interest to mention that a #6 Cu THHW conductor has a 65A rating as well [Table 310.15(B)(16) (formerly Table 310.16)]


I think that is a reach.

What is the fee air rating of that conductor as it is often run?

What is the rating of a 6 bare?


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## Celtic (Nov 19, 2007)

BBQ said:


> I think that is a reach.
> 
> What is the fee air rating of that conductor as it is often run?
> 
> What is the rating of a 6 bare?


 :surrender:

I'm just walking down memory lane here....


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## BBQ (Nov 16, 2010)

OK, 


So lets talk about transformer springs ....... :laughing:


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## HARRY304E (Sep 15, 2010)

BBQ said:


> I think that is a reach.
> 
> What is the fee air rating of that conductor as it is often run?
> 
> What is the rating of a 6 bare?


Table 310.15(B)(21) (formerly Table 310.21)

Bare 124 amps,Covered 130 amps.


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## HARRY304E (Sep 15, 2010)

BBQ said:


> OK,
> 
> 
> So lets talk about transformer springs ....... :laughing:










:laughing::laughing:


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## Big John (May 23, 2010)

Celtic said:


> I had read somewhere that a ground rod was capable of carrying 65A


 Yeah, I can't make that jibe: The soil resistivity is likely to limit it to a lot less than 65A, and a mass of copper like that is going to be able to carry a lot more than 65A.


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## Celtic (Nov 19, 2007)

BBQ said:


> OK,
> 
> 
> So lets talk about transformer springs ....... :laughing:


Boing








Boing 

:laughing:


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## EJPHI (May 7, 2008)

I believe the water bond pipe bond was intended to clear faults and reduce current flow on the plumbing. So you have to size the bonding wire based on the service size 200A=#4.

The ground rod is installed for lightning protection and current flow is limited by the ground rod to earth impedance (not just resistance), so a #6 wire is considered acceptable regardless of the size of the service.

I am just an :nerd: so take this with a grain of salt.

EJPHI  (this one is cooler)


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