Table 250.102(c)(1).

[jpujols01]

Good morning....
I'm looking to this table and it says that to size the ground wire when is 1100 kcmill or bigger we have to find the 12 1/2% of the large ungrounded conductors or the sum of parallel ungrounded conductors.
Can anybody here give me a good example of this please...


J Pujols.

 

[jpujols01]

J Pujols.

 

[Dennis Alwon]

Let's get the terminology correct. Ground wire means nothing in the context you stated. T. 250.102(C)(1) is the same as T.250.66 until you get to over 1100kcm. This table is for the grounded conductor (Neutral) and main bonding jumpers etc.

T. 250.66 is for the grounding electrode conductor. Apparently there was alot of confusion with them so they separated it and then added a separate note for over 1100kcm

Okay so if we have a conductor that is 1750KCM we know that is equivalent to 1,750,000CM. 12.5 * 1,750,000= 218750CM. Now go to Chapter 9 Table 8 and look for the wire size that is equal to or more than 217,750 = 250KCM

 

[jpujols01]

Got it and thank you very much.


J Pujols.

 

[infinity]

A photo may help. 5 set's of 500 kcmil (200% neutral) = 2500*12.5% = 312500 or 350 kcmil bonding jumper. Notice the GEC is #3/0.

 

[jpujols01]

Thanks but I may have to find out when the new table will be adopted in nyc, I just have a inspection and the inspector still using the 250.66 table.


J Pujols.

 

[Smart $]

Thanks but I may have to find out when the new table will be adopted in nyc, I just have a inspection and the inspector still using the 250.66 table.


J Pujols.

Even earlier editions had the 12.5% requirement for over 1100/1750kcmil... it just wasn't located in Table 250.66. See 250.24(C)1), 250.28(D)(1), and 250.30(A)(3)(a).

 

[infinity]

Thanks but I may have to find out when the new table will be adopted in nyc, I just have a inspection and the inspector still using the 250.66 table.


J Pujols.

As Smart stated this is a new table (2014) but the requirements have not changed from the 2008 NEC. An inspector using the 2008 NEC should still know about the 12.5% requirement.