I recieved a power company useage sheet for an existing residence that showed the largest useage for a month at 1145KWH. My question, how do you convert KWH to KW? I am adding a 4 car garage to the service; I know that by NEC I can take the existing peak KW x 1.25 and add new load to derive at my new load summary. Thanks in advance for the help.
From the info you supplied, all we can see is that the average load during that month was less than 7 amps. So, that info is really of no use and does not indicate a peak value.
What you have to watch for is heating loads. They can suck up a lot of juice.
Example, electric water heater, 16.6 amps.
Plug in space heater, 12.5 amps.
Each burner on an electric range, 16.6 amps.
6000 watt electric oven, 25 amps.
Electric clothes dryer, 20-25 amps.
If the house doesn't have any of these (all gas), that is a big difference from a house that does. If all the above were turned on at once, that is just a tad over 140 amps.