Residential generator and 200 amp transfer switch 150 amp panel

[Greg1707]

Residential transfer switches appear to be available in 100 or 200 amp sizes. I would like to install a 150 amp main panel.

If I have a 200 amp transfer switch would the conductors from the METER to TRANSFER SWITCH to MAIN PANEL all have to be sized for 200 amps?

 

[ActionDave]

Not necessarily.

Automatic transfer switch or manual? Is there a breaker or service disconnect ahead of the transfer switch. You only need to protect equipment equal to or less than its rating so it would be acceptable to feed a 200A switch from a 150A service disconnect.

 

[Greg1707]

This is for an automatic transfer switch. Are the cables, SEC to switch and SER from switch to panel, required to be sized for 200 amp?

 

[ron]

The ATS can be any size equal to or larger than the calculated load per Article 220.
The service and conductor size connected to the ATS can be any size equal to or larger than the calculated load per Article 220, although the protection cannot be larger than the rating or ampacity of anything downstream.

So for example, if you calculate a 100A load , the ATS can be 200A and the service size can be 100A

 

[Greg1707]

Thanks, I failed to realize that I can change the main breaker within transfer switch. I can install a 150 amp breaker.

 

[kwired]

Thanks, I failed to realize that I can change the main breaker within transfer switch. I can install a 150 amp breaker.

That adds cost, can you order it with a 150 amp breaker even though the transfer switch itself is rated 200 amps?