What size transfer switch for 225 amp service?

[patricknola]

Good afternoon, I'm giving an estimate for a generac generator install. It's a home with a 225 amp service. The meter is rated for 320 amps, the meter pan and panel are 225 amps. What size transfer switch do I want to pass inspection? 300 amps? TIA

 

[AC\DC]

Well I don’t know without looking what transfer rating are generac panels.
It has to rated for at least 225 amp. Since that was the calculated load apon install.

 

[don_resqcapt19]

And don't forget about the requirements of 702.4(B).

 

[ScottWJ]

Like a lot of answers, it depends...
Will it go between meter and main panel with no further design? If so, it will need to be 225A or more, and service entrance rated.

You can use 220.87 to arrive at a more realistic demand. If this lets you use a smaller transfer switch (with OCP in it), assuming this is before the house panel, the 225A MCB in the house panel becomes unimportant. For a whole-house system, you will need to do this calculation anyway to size the gen.

If its not a whole-house application, you can size for only the partial loads, sub-feed the transfer switch from the main panel, to a second panel that will only have the gen supported circuits. Some transfer switches have this sub-panel built in.

 

[hillbilly1]

May be difficult to get a 225 amp single phase transferswitch in any form. Not that common in residential. A non SE rated 300 would probably be easier to get, but you would need a 225 amp ocp before it.

 

[LarryFine]

A 200a service-rated ATS would render this a 200a service. Would that adequately serve the house?

 

[James L]

A 200a service-rated ATS would render this a 200a service. Would that adequately serve the house?

If not, a ittle bit of load shedding would get it there

 

[qcroanoke]

May be difficult to get a 225 amp single phase transferswitch in any form. Not that common in residential. A non SE rated 300 would probably be easier to get, but you would need a 225 amp ocp before it.

Onan used to make them. Not sure if they still do.

 

[hillbilly1]

Onan used to make them. Not sure if they still do.

Kohler had some weird three phase ones, 108 amp is one that comes to mind. A lot of orange boxes had those.

 

[kwired]

If not, a ittle bit of load shedding would get it there

Technically it would have to shed load even when running from utility if the load calculation was over 200.

So if 225 is what is needed then any transfer switch that serves the entire load also needs to be 225 minimum.