Scott, I basically agree with Mark and John.
For a major expenditure and installation like a 40-50kW gen set, you really
should have a professional do it, including determining the size. You'll also
need a major fuel tank, probably a concrete pad, and don't forget that 200 amp,
240 volt wiring.
> 200A service means 48kW can be pumped through the house, but this is
> highly unrealistic.
I'd say it depends on the circumstances. I've popped my 100A main breaker more
than once, and all of my heat is done by fossil fuel.
> I get a 'brownout' every time my on-demand hot
> water heater and its 28kWmax kicks on).
And right there is the difference between 100A and 200A.
> Remember that you can turn off the A/C while cooking to reduce the peak
> loads.
There are even "load centers" available that will handle this automatically.
Not cheap, but if it means the difference between a 7kW and a 40 kW gen set, it
might be worth it.
> one guy told me I could get away with a 6500kW,
I assume that's really 6.5kW ... you probably can "get by" on that, but almost
certainly it will not meet your goal of "not knowing the power is off". Still,
is it really important that you have the A/C running while you're in the shower
?
> while
> > another told me no less than 40kW would do.
It's possible that even 40kW will NOT do ... you just have to do the analysis to
be sure.
> > now, I appreciate that when the a/c kicks on (or the fridge, etc.) it
> > draws more power at first, however, it'd still trip the breaker if it
> > out-drew it, even at start-up, right?
No, not necessarily. Home-service breakers almost always have some tolerance
for short-term overloads, just so you don't get "nuisance trips" when motors
start (which may draw 2 or even 3 times as much current as when they are
running). And it's not uncommon to find "motor service" breakers with even
longer trip times for small overloads.
Most gen sets can also handle some overload (generally called "peak" load or
some such), but it's very rare to find one that can power a 100% overload for
even a few milliseconds. The proper way to deal with this is to find out what
the peak current is for all your loads, add all those together and match the gen
set peak power to it.
Randall
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