5000 Watt Generator vs. In Ground Water Pump

[LowGear]

I was talking to a friend in the Pacific Northwest of the United States and he mention he had his first power loss of the year.  Kind of his marker for Winter.  He mentioned his generator would run his water pump.  The generator sets in his detached garage and plugs into an old dryer receptacle.  Runs most else and he throws the water heater breaker when he tries to get the water pump going.

I know the water pumps have a ferocious appetite when starting but 5KW?

[mobile_bob]

it really doesn't surprise me,

depth of the well has an effect,
well head, plus pressure tank head

very much like a locked rotor demand seen on A/C compressors, most especially if they are asked to restart
after a momentary loss of power.

i have read that some old refrigerators have a startup demand of as much as 9x the running current.
that is a tough load to service!

[mike90045]

Most electric motors can easily pull 10x their running current, when starting

[Henry W]

The 120 volt AC unit on my RV has an LRA rating of 56 or 58 amps. That is one of the reasons I'm using a generator head that has a 8.4 kVA rating with a 10.5 kVA surge rating. I see people at the RV parks using an RV generator with only 3650 watt rating running their ac units and they get by but I don't want to take that chance. Its best to have a larger head and de-rate it.

[LowGear]

Thanks,

How big of generator should he be on the look for?

[sailawayrb]

You need to know the pump HP and the pump depth in the well to do an accurate calculation.  Didn't we do this for you a while back when you were soul searching for a generator?

I have a 1 HP pump at 180 feet and my portable 5C/7.5P kW generator will run it fine.  Well pumps use pump controllers that have a starting relay/capacitor circuit and additional starting wire that goes to the pump to handle the initial higher starting current draw.  So the generator doesn't actually have to provide much of this additional starting current.