Got an 1800 sq ft house with 4 ton a/c, electric range, washer, dryer,
microwave and various low draw lights, etc.
What is a good kw number for a "whole house" generator that will, for sure,
run the lights and a/c, at least? I'm thinking 15kw would do it, once stuff
was online. I'm told to go from the biggest load to the smallest in
bringing stuff online.
What's the SEER of the A/C? Divide 48000 by the SEER and it will give
you the steady state current requirements in watts.
Note that starting surge for A/C systems can be six times or more the
running load. A "hard start" kit will reduce the starting current
requirements, so if capacity is a problem then have a hard start kit
installed. Don't forget that once the thermostat is satisifed and the
A/C shuts off you'll still have all the rest of the load there....and
the A/C may not restart unless you shed that load first.
Your probably going to need a 15kw just to get the a/c started.
15000 watts translates into 62.5 amps.
A/C 20 amps running, starting 120 amps, better part of a
second at least
Oven 40 amps
Water heater 25 amps
Washer 20 amps
Dryer 30 amps
these figures might be a little on the high side except for the washer. When
washers go into spin mode they will draw upwards of 18 amps, at least mine
will. Your compressor will have a LRA number this can also be used as the
There are a ton of variables, some interlocks will help.
Make sure that the generator you choose is rated for 100% loading. Most
stand-by units are 80% of full load. Then comes the fuel issue.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.