# grounding



## Super Tom (Mar 9, 2011)

Can anybody tell me how many ohms of resistance I should have on my ground wire for a typical 200 amp service


----------



## MDShunk (Jan 7, 2007)

zero ohms.


----------



## JohnR (Apr 12, 2010)

^^^^ what he said^^^


----------



## backstay (Feb 3, 2011)

It would depend on how long the wire is what type and what size. Chapter 9 table 8


----------



## HARRY304E (Sep 15, 2010)

Super Tom said:


> Can anybody tell me how many ohms of resistance I should have on my ground wire for a typical 200 amp service


You should read all of article 250..

Welcome to the forum..:thumbup: 

*250.53 Grounding Electrode System Installation.*
Informational Note: See 547.9 and 547.10 for special
grounding and bonding requirements for agricultural
buildings.​

*(A) Rod, Pipe, and Plate Electrodes. *
​​Rod, pipe, and plate​
electrodes shall meet the requirements of 250.53(A)(1)
through (A)(3).​​*(1) Below Permanent Moisture Level. *​

​​If practicable, rod,​
pipe, and plate electrodes shall be embedded below permanent
moisture level. Rod, pipe, and plate electrodes shall be
free from nonconductive coatings such as paint or enamel.​​*(2) Supplemental Electrode Required. *​

​​A single rod, pipe,​
or plate electrode shall be supplemented by an additional
electrode of a type specified in 250.52(A)(2) through
(A)(8). The supplemental electrode shall be permitted to be
bonded to one of the following:
(1) Rod, pipe, or plate electrode
(2) Grounding electrode conductor
(3) Grounded service-entrance conductor
(4) Nonflexible grounded service raceway
(5) Any grounded service enclosure​​_Exception: If a single rod, pipe, or plate grounding electrode_
_has a resistance to earth of 25 ohms or less, the_​
_supplemental electrode shall not be required._​


----------



## MDShunk (Jan 7, 2007)

He said wire, not electrode. The typical grounding electrode conductor ("ground wire") is normally pretty short, and if an electrician was to measure it, he'd measure it with a DMM, since most ec's don't own a DLRO. With those facts, my answer of ZERO remains.


----------



## Zog (Apr 15, 2009)

MDShunk said:


> He said wire, not electrode. The typical grounding electrode conductor ("ground wire") is normally pretty short, and if an electrician was to measure it, he'd measure it with a DMM, since most ec's don't own a DLRO. With those facts, my answer of ZERO remains.


Dang, I was about to pounce and say there is no such thing as Zero ohms, then you had to go clarify


----------



## forgotflying (Mar 2, 2011)

pound 2 ground rods and ∞ works :jester:


----------



## miller_elex (Jan 25, 2008)

Did you put one probe on the slab, or in the dirt??


----------



## McClary’s Electrical (Feb 21, 2009)

miller_elex said:


> Did you put one probe on the slab, or in the dirt??


 




Shunk was referring measuring from one end to the other.


----------



## Dennis Alwon (May 9, 2009)

Super Tom said:


> Can anybody tell me how many ohms of resistance I should have on my ground wire for a typical 200 amp service


Can you give us more info?


----------



## MDShunk (Jan 7, 2007)

Zog said:


> Dang, I was about to pounce and say there is no such thing as Zero ohms, then you had to go clarify


There's always one kid like you in every class. :laughing:


----------

