Article 250.66 Note #2 Question?

[spitter1020]

Article 250.66 Note #2 States: Where there are no service-entrance conductors, the grounding electrode conductor size shall be determined by the equivalant size of the largest service entrance conductor required for the load to be served.
I have a 400 amp main switch with a 350 kcmil ungrounded service entrance conductors present which i sized the GEC at #2 cu using Table 250.66. However the inspector stated that on a service lateral application i have to size the GEC to 250.66 Note #2 then using Table 310-16 to find wire size of the load to be served (400 amp) then going back to table 250.66 with your higher wire size. Any input on this? Is this true with a service lateral application with srvice entrance conductors present?

 

[Smart $]

Note 2 only applies if there are no service entrance conductors.

From what I gather from your description is that you do have service entrance conductors but they are simply the extension of the service lateral. There is no exception for this condition that I'm aware of. The inspector is likely correct in principle, but there is no such code requirement as far as I know. Ask him to cite reference... politely!

 

[frizbeedog]

I believe your inspector is correct.

Service laterals by definition end at the connection point to the service entrance conductors. They are not themselves, service entrance conductors.

But since you have equipment that has none required to be installed.....You size as if you would install them.

You have buss bars connecting the laterals to the system disconnect.

That's what note 2 means.

 

[spitter1020]

Thak you gentelmen for your input. Over the weekend I did more research and also found some great input on Note #2 in the book "Electrical Grounding and Bonding" by J. Philip Simmons.
:smile:

 

[eprice]

spitter1020,

I suspect frizbeedog (and the inspector) are correct, but there is not enough information in your original post for me to be sure.

Is the main switch part of a meter/main combo, or do you have a separate meter enclosure with conductors between the meter and the main switch?

Where do the 350 kcmil conductors begin and where do they terminate?

Are they copper or aluminum?

 

[frizbeedog]

Thak you gentelmen for your input. Over the weekend I did more research and also found some great input on Note #2 in the book "Electrical Grounding and Bonding" by J. Philip Simmons.
:smile:

You're welcome. :smile:

Try Soares, Book on Grounding and Bonding, if you get the chance.