Maximum PV System for 400A Service

[Zyb]

For a 400A service what is the maximum continuous current that I can tap 320A (80% of 400) or 400A?

Resizing the wire (Blue wire) to accommodate the 320A, would this still be a code complaint design? Thank You!

 

[ggunn]

As long as there is no OCPD ahead of the tap, i.e., the conductors from the 400A service to the MSP in question are service conductors, and there is a 200A main breaker on that MSP, I believe you are OK.

 

[Zyb]

Thank you @ggunn. any thoughts on this diagram? I will be using the existing two wire, parallal to JB and use multitap connector.

 

[jaggedben]

You haven't said anything about wire sizes. The conductos between the PV and the multi-tap blocks, and between the blocks and the meter, need to be rated 400A. From the blocks to each existing disco can be the existing 200A.

Otherwise it looks fine to me.

 

[electrofelon]

You haven't said anything about wire sizes.

Yes, an important detail. Often the conductors in such a setup would be 4/0 AL using next size up rule which would leave you with 288A of continuous loading available.

 

[Hv&Lv]

Thank you @ggunn. any thoughts on this diagram? I will be using the existing two wire, parallal to JB and use multitap connector.

I realize this is a drawing, but just to make sure, I wouldn’t connect the wires to the junction box connectors the way it’s drawn out. The incoming from the meter base should be at opposite ends, or at least staggered with the load wires between the line wires.
The way it’s drawn all load is concentrated at one spot on the connector Between the second and third “screw”

 

[electrofelon]

For a 400A service what is the maximum continuous current that I can tap 320A (80% of 400) or 400A?

Back to your original question, a class 320 Meter is rated 320 continuous so you could never apply more than 320 of PV even with the biggest conductors in the world.

 

[Hv&Lv]

Back to your original question, a class 320 Meter is rated 320 continuous so you could never apply more than 320 of PV even with the biggest conductors in the world.

Good point. I assumed it was a K base.

 

[electrofelon]

Good point. I assumed it was a K base.

I dont think in 20 years of this I have ever seen a K base. Granted could be a regional/utility thing where its more common in certain areas.....

 

[electrofelon]

It's annoying, but Seattle city light doesn't even allow class 320's for other than residential. Had some times 200 didn't quite cut it, so I had to go to a CT just for a 300-400A service.

 

[jaggedben]

Funny, I just saw a CL400 today, but that doesn't happen often. I know I've seen at least one K-base on a residence, probably at least one other besides that and possibly more I didn't realize because dealing with interconnection wasn't my responsibility. Around here if it's above CL320 the rules start to change.

 

[PWDickerson]

You should check that the utility transformer is adequately rated for this much backfeed.