GEC sizing

[nizak]

I have a 400A (320 continuous) meter base that is being installed on a new residential build. Curently there will be a 200A disconnect adjacent to it to feed the new dwelling. The larger base has been installed for future expansion on the property in the coming years. My question is does the GEC at this point need to be sized to the potential load that may exist in the coming years or can it be sized to the 200A that is presently? I'm asking because the POCO will not allow a GEC inside their meter(if so I would upsize at this time) therefore the only termination point for it at this time is the 200A disco.The only means of adding a GEC in the future would be driven rods, and the other electrodes that are in place now would not be accessible. Thanks.

 

[suemarkp]

Are there Service Entrance Conductors under the perview of the NEC (e.g. an overhead mast feeding the meter)? If so, you would size the GEC and water bond per those (one solution) or run GEC "taps" from each disconnect (when the future disconnects arrive) to the GEC and water.

If you only have a UFER or rods, then you don't need to worry about a larger GEC than a #4. But the water is always sized per 250.66.

Where is the future expansion occurring -- in that same building or in new detached structures? If all future work will be in detached structures, then you can probably just size the GEC based on the conductors feeding the disconnect on each structure (e.g. #4 cu for the 200A disconnect) and be done.

If you have metallic water piping to bond per 250.66, it would be prudent to put in a larger wire now if running a larger one or additional wire in the future is going to be difficult, especially if the water pipe in the earth is also metal causing you to have the bond the pipes within 5' of where they enter the building.