I have a 10K/12K surge generator but there are times when I might only want to run my Wayne 1/2 HP sump pump off a smaller generator. I'm not sure if I can do this with a smaller portable Honda.
In searching the net, one site says a 1/2 hp sump pump needs 1050 watts to run and 3200 to start. I had planned to get the Honda 3200/2600 watt portable but now I'm not so sure that if that will work. I don't want to burn up the generator overloading it. There is no info with my pump.
Can anyone offer any insight on watts or generator to run a dedicated 120 line for a sump pump for power outage?
For small inverter generators, in general the guidelines out of some of the older inverter generator manuals typically stated the following.
Pure resistive loads can be run at 100% of generator rating.
Incandescent lights or electric resistance heater fall under this catagory. No inductive loads.
So a 1000 watt inverter generator can run 1000 watts of these type of loads as there is no start up surge.
Power tools with can be used at 80% to 90% of the generator rating.
Depends on how the motor is wound, which effects the magnetic coupling ability of the power tool.
Motors can be used at 40% of the generator rating, this is dependant on how they are made. Motors loads are typically around 85 percent efficient.
To find the motor load that a 1000 watt inverter generator can safely start, we would use some simple math from the older manuals.
1000 watts x 40% = 400 watts.
400 watts x 85% (Motor efficientcy) = 340 watts.
The 1000 watt inverter generator can safely start a 340 watt motor load (according to these older manuals).
I would not try to start any motor under load using this math.
I have 2000 watt Yamaha and Honda inverter generators and use them on a 1/2 HP trash pump. They will start the pump with the outlet valve closed (no load). I then open the valve and it is not a problem to add pumping load to the motor.
I can't start the motor if the valve is open, which places to much load on either generator and they will stall out. Not good for longevity of the motor or the generator. Voltage sag=higher amps in inrush current.
I would never reccommend a 2000 watt gen. to start this load for a customer. I would tell them 4000 watt gen. is what they need as it will start the motor under load.
1/2 HP = 373 watts continuous. 373 x 10 = 3730 starting watts needed.
Some of the cheaper inverter generators do not start motors using the 10 times inrush rule of thumb. So your mileage may vary depending on quality of gen. set.