Grounding Electrode

[resistance]

Am I reading this right. 250.66 (B) says: You do not have to use a GE Conductor over a #4-if encased in concrete, but you do have to size it per T. 250.66 if not encased?

 

[LEO2854]

Am I reading this right. 250.66 (B) says: You do not have to use a GE Conductor over a #4-if encased in concrete, but you do have to size it per T. 250.66 if not encased?

250.66 (B) Connections to Concrete-Encased Electrodes. Where the grounding electrode conductor is connected to a single or multiple concrete-encased electrode(s) as permitted in 250.52(A)(3), that portion of the conductor that is the sole connection to the grounding electrode(s) shall not be required to be larger than 4 AWG copper wire.

Remember "Key Words"

 

[LEO2854]

Also read 250.52(A)(3)

 

[kwired]

The GEC that is the "sole connection" to a concrete encased electrode never needs to be larger then 4AWG copper. If it is also connecting to other elecrodes or is connecting to another type of electrode then you still need to use whatever is called for by table 250.66.

There is similar wording for rod, plate or pipe elecrodes, but the size is 6AWG copper for those.

I think the idea here is those electrodes have been determined to not be able to handle any more current then those conductor sizes can deliver, so larger conductors are not necessary.

Water pipe electrode, building steel electrodes, could have low enough resistance and need larger GEC if the service or feeder conductors are large enough according to T250.66.

 

[resistance]

Ok, thank you! I Thought I was loosing it! Then again, the topic is grounding.