"David Flew" wrote

I feel a switch is important - it needs only be a simple on/off
switch in
parallel with the float switch. It lets you test run the pump
without lifting the floors.

Convenient but, like a lot of conveniences, not necessarily a good
idea simply because it is convenient. You ought to be lifting the
floors to access water level, look for debris jamming the float
switches and pumps, verifying that the pump is actually moving water
and not just making a whirring noise. As long as you are down there,
you might as well use the handy float switch. This is a prime failure
point itself so verifying function is a good idea.

A manual switch in parallel with the float would be a good back up to
float switch failure but I would put it under the floor boards for
these same reasons. As long as it is there, why not make it a float
switch as well? Then, if the water gets that high because of low
switch failure, the pump will go on. This solves the problem of
difficult access to the low switch.

A nice thing about my circuit

http://home.maine.rr.com/rlma/Bilge.htm

is that just flipping the high switch momentarily runs the system all
the way down so I don't have to hold the switch up the whole time. I
know this is a more complicated system than most people want to bother
with but it was fun to put together and works great.

--

Roger Long