new 3 phase service grounding, bonding

[Stevenfyeager]

I am estimating a 200 amp 3 phase new service, 208 v. The business is a wood pole barn with sheet metal siding. I don't think there is any steel at all except the siding. My inspector said I need two ground rods for grounding and bond to the building if possible. I guess the grounding with the two rods is the only thing I can do? I may have to ground to the water line.?... Also, sizing for grounding elec conductor; 250.66 A says #6 Cu, but for my 200 amp, (using 250 AL), Table 250.66 says I need # 2 Cu. Can you please help me? Thank you.

 

[LarryFine]

Conductor to only rods can be #6, the water pipe is based on amperage,

 

[Cow]

We would drive rods, and hit the water pipe if it was metal.

That's it.

 

[ActionDave]

We would drive rods, and hit the water pipe if it was metal.

That's it.

That or a sewer pipe is one of my biggest fears.

 

[Stevenfyeager]

We would drive rods, and hit the water pipe if it was metal.

That's it.

I looked at the water line today, it is copper. I have a question on wire sizing. For this 200 amp 3 phase new service, I am seeing 250 AL in Table 310.15 B 16 for XHHW. Then on 250.66 table, I see I would need #2 Cu for the water line wire, while using #6 for the two rods. Do these sound right? Thank you !

 

[kwired]

I looked at the water line today, it is copper. I have a question on wire sizing. For this 200 amp 3 phase new service, I am seeing 250 AL in Table 310.15 B 16 for XHHW. Then on 250.66 table, I see I would need #2 Cu for the water line wire, while using #6 for the two rods. Do these sound right? Thank you !

Look again, #4 copper or #2 aluminum GEC.

 

[Stevenfyeager]

Look again, #4 copper or #2 aluminum GEC.

oh yes, I see, you are right, thank you, #4. Another question; Do 4 runs of 250 AL in a 2 1/2 inch rigid riser sound correct?
Or should I use 3 inch? Also, would you downsize the neutral?
Thank you again.

 

[kwired]

oh yes, I see, you are right, thank you, #4. Another question; Do 4 runs of 250 AL in a 2 1/2 inch rigid riser sound correct?
Or should I use 3 inch? Also, would you downsize the neutral?
Thank you again.

If calculated load is less then 180 amps 4/0 aluminum is permitted to be used. I typically would use 2/0 for neutral without calculating max unbalance, in some cases where I know a pretty significant portion of the load is line to line only I might even go smaller then that with the neutral. In no case can the service neutral (grounded conductor) be smaller then the required grounding electrode conductor though.

Common example for me is irrigation wells - service that basically supplies a single load or very limited variety of loads, and none of it ever has line to neutral loads. In that case I very well may use #2 aluminum for the grounded service conductor for typical 200 amp service.

 

[lordofthisworld]

I looked at the water line today, it is copper. I have a question on wire sizing. For this 200 amp 3 phase new service, I am seeing 250 AL in Table 310.15 B 16 for XHHW. Then on 250.66 table, I see I would need #2 Cu for the water line wire, while using #6 for the two rods. Do these sound right? Thank you !

#4 copper would be sufficient.