Peer check Riser please

[Designer69]

I have attached the riser diagram I propose for a 120/240 1-ph system that contains emerg. loads/generator.

Please take a look and see if you agree, or if you suggest changes to make it better/more economical.

(note, I am breaking it up to emerg. and optional because the owner wants to also supply heating equipment from EG, which I believe can not go on emerg. panel, please let me know if you also concur on this)


Thank you

 

[Designer69]

the other option I can think of is below. The reason I am thinking this could make any sense is to possibly help with article 700.28, selective coordination requirement of emerg. system (and not put them on same mcb).

 

[ramsy]

Why not go to LOCAL AHJ planning department with this?

If they want it a different way, your wasting your time on the internet.

 

[Sunny_92]

the other option I can think of is below. The reason I am thinking this could make any sense is to possibly help with article 700.28, selective coordination requirement of emerg. system (and not put them on same mcb).


View attachment 20397

I agree that you'll probably be able to achieve selective coordination more easily with this arrangement. If you go with your first riser diagram and the available fault current is high enough, you may be forced to use a large power circuit breaker that has an instantaneous trip function that can be turned off. The biggest disadvantage I see to your second riser is that it will likely require an extra piece of gear.

 

[charlie b]

What are the article 700 loads? If it is just egress lighting, then why not use unit equipment or a central inverter? That would take the emergency system ATS out of play, and eliminate consideration of selective coordination. The backup generator would be for optional standby loads only.