Table 250.66 Note #2

Grouch1980

Senior Member
Location
New York, NY
When does Note #2 from Table 250.66 apply? Are they talking about a service switchboard with copper bus bars, where you directly terminate service lateral conductors from the utility? But those copper bus bars would be considered service entrance conductors...
 
Last edited:

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
After 30 years I still get tripped up on service conductors and Service-Entrance Conductors
Note 2 states
Where there are no service-entrance conductors, the grounding elec-
trode conductor size shall be determined by the equivalent size of the
largest service-entrance conductor required for the load to be served.
See the definitions and the informational notes

Service Conductors. The conductors from the service point to
the service disconnecting means.

And
Service-Entrance Conductors, Underground System. The
service conductors between the terminals of the service equip-
ment and the point of connection to the service lateral or under-
ground service conductors. (CMP-4)

Informational Note: Where service equipment is located outside
the building walls, there may be no service-entrance conductors
or they may be entirely outside the building.
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
An underground feed to a meter main where the poco owns the underground feed is an example. Poco can run weenie wires to the meter main if they wish.
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
The power company generally runs conductors smaller than the NEC requires. My 200A service is fed with #2 Al overhead and 1/0 Al underground. These sizes were chosen by the utility. I had a 400A service that had 1/0 Al overhead.

So you don't base the water bond based on those "teenie weenie" sized wires. You instead use what size you'd need to run if the NEC governed the conductor install.
 
Top