> Our power went out last night, so I ran an extension cord from the little
> 1000W Honda (EX, not an EU) generator off down to the sump pump, plugged
> it in, and was dismayed to see the pump not work. Later on, power came
> back on and the pump worked fine.
>
> I can't imagine that pump is anything more than a 1 hp unit,
> probably more
> like 1/3 or 1/2 hp... What size generator do I need to make that puppy
> work?
Induction motors (which is probably what your sump pump has) can draw many
times their nameplate current at startup ... 3 times is a good rule of thumb
but some draw as much as 8 times.
I would suggest contacting the maker of your sump pump, and asking them how
much startup current it draws. Another alternative might be to try to
measure it yourself, but it's tricky unless you have access to some
specialized tools.
Then as someone else already suggested, buy a gen set that will put out that
much current.
"By thumb" : 1/2 hp = 625 volt-amps run, about 5.2 amps. Times 3 = 15.6 amps
... most likely a 1500 watt gen set would start it (with nothing else on the
circuit), but 2000 would be safer. Still far better to get the actual
numbers instead of guessing.
It's possible to find "soft start" motors that don't draw as much startup
current, but they aren't common (especially in the smaller sizes). If you
decide to change your sump motor (which might be cheaper than a new gen
set), check with a place that caters to people who generate their own power.
Randall
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