What size generator do I need for a food truck?

Add up the watts of everything electric that runs at the same time, then pick a generator rated above that total with room to spare. For scale, the Cummins Onan QG 5500 LP, a built-in generator, is rated at 5,500 watts and 45.8 amps at 120 volts.

Watts are volts times amps, so read the amps off each spec sheet. A True TSSU-48-12 prep table draws 5.8 amps at 115 volts, about 670 watts. A True TUC-27 undercounter refrigerator draws 2.0 amps and a True T-23 reach-in 2.2. Those three come to about 1,150 watts. Then add air conditioning, the water pump, lights, the register and any electric cooking.

The NFPA wants generator exhaust at least 12 feet from openings, air intakes and exits. See generator and the food truck equipment list.