22kw standby generators

[griffelectric]

why does a 22kw standby generator use a 200amp transfer switch, if this generator only produces 91 amps 22000 / 240 volts ?

if you have a 200 amp residential service and you want a backup generator for standby power, should you install a 48kw generator

48000/240volts = 200amps, instead of a 22kw generator?

 

[Rampage_Rick]

Well if the transfer switch is supposed to switch the entire service, it has to be sized accordingly. If you have a 200A service you'd need a 200A transfer switch. The rating of the transfer switch must be equal or higher than the rating of the circuit it's switching.

Now in reality, there's probably no where near full load on that service. There's a good chance that 22 kW will suffice for the home in question. I can make do in my 1100 sq-ft rancher on a 7.5 kW generator assuming I don't do laundry. Why spend double (or more) for a 48 kW generator if you'll never use the extra capacity?

 

[shortcircuit2]

702.4(B)(2) of the 2011 NEC says that an automatically transferred generator shall be capable of supplying the full load served unless load management is used.

Calculate the load according to article 220 of the NEC for sizing generators.

 

[Strathead]

702.4(B)(2) of the 2011 NEC says that an automatically transferred generator shall be capable of supplying the full load served unless load management is used.

Calculate the load according to article 220 of the NEC for sizing generators.

This is all assuming you don't plan on using air conditioning. The startup requirements for air conditioning require a generator usually larger than the calculated load.