11/2 hp motor will drow 11.35 amps. x 220 = 2497 watts
at start up perhaps x 2.5=6242.5 watts

"Reinhard" wrote in message
...
Robert wrote in news:1186345007.745027.127100
@r34g2000hsd.googlegroups.com:

I am having a well drilled to 400' and will get a 220v 1.5 hp motor
for the pump. I would like to buy a back-up generator in case of
extended power outages. Can anybody tell me what watt generator I
would need? Thanks - Robert



1 hp = 746 watts so you so need at least 1120 watts to run a 1.5 hp motor.
The actual wattage depends on how much power the pump draws when it starts
- starting draw can be 2 or 3 times running power, usually just 2 or 2.5
times. Also, a generator can usually supply more than the rated power for
a
short time, enough time to get pump to speed. A 3000 watt generator should
be plenty and you could probably get away with 2500 watts.