Any codes issue here?

[anbm]

See attached image for sketch of elec. one line diagram, does anyone see any code issue?
I.e. using new 400A services (both normal and generator power) to power an existing 1,000A panel with 1,000A main breaker because
max. demand load of the panel is only 210A. No need to comply with coordination study in this case? Thank you.

 

[HarrySlother]

Coordination study isn't required for an optional standby system. Feeding the 1000A system with 400A is fine, as long as the inspector buys off on your demand load. See 220.87

 

[anbm]

Coordination study isn't required for an optional standby system. Feeding the 1000A system with 400A is fine, as long as the inspector buys off on your demand load. See 220.87

400A wires land to 1,000A breaker in downstream panel is not an issue?

 

[HarrySlother]

You'll have to check the breaker for it's specific lugs and compare it to the wire you're using.

I'd think you could safely use 500K Copper with a 1000A breaker but of course, double check that with your specific breaker.

 

[anbm]

You'll have to check the breaker for it's specific lugs and compare it to the wire you're using.

I'd think you could safely use 500K Copper with a 1000A breaker but of course, double check that with your specific breaker.

I meant code issue, small wire amp. vs larger breaker amp. it ties to…

 

[HarrySlother]

Oh gotcha. That’s also not an issue here because the wire is properly protected upstream

 

[jap]

You'll never get more than 400 amps out of that Service the way it is drawn.

Most times you would have the Utility Power feeding the 1000 amp Main Distribution Panel with a Sub Feed Breaker in it through a Xfr Swich to feed a panel for you're Emergency Loads, then, have the generator through the Xfr side of the Switch to back it up.

As it is, the existing Main Distribuition Panel in the drawing would be nothing more than a glorified 400 amp MLO Panel.

Jap>

 

[ModbusMan]

Coordination study isn't required for an optional standby system. Feeding the 1000A system with 400A is fine, as long as the inspector buys off on your demand load. See 220.87

May not be required, but can be helpful... we've been able to reduce many of our offices from category DON'T TOUCH IT down to 2 or 3 just by adding generator output breakers, having coordination studies done for both utility and generator power, and dual-labeling.