I just did some plumbing changes on my well tank. The tank is in a
cistern since there is no where else to put it (no basement). The
well is 20 feet away, the control box is in a shed about 30 feet away
(which is also the power source).

Anyhow, I discovered that who ever wired the pressure switch, only
shuts off one side of the 240V line. The other side is always ON.
It works fine, and has been this way probably since the pump was
installed in 1973 (I got the documentation when I bought the property
about 6 years ago).

Anyhow, I know this is not correct. At the same time, changing it
would require me to dig up the 30 feet of underground UF cable and
replace with 12-3 UF cable, bust a new hole in the cistern wall to run
to the wiring in the shed, and re-cement. I know, this may be hard to
understand, the system is really wired strangely, but there really is
no other way I can see to do it when the well is in one place, the
cistern in another, and the shed yet another. The underground wiring
forms a triangle between the three objects.

Either way, correcting this require a lot of work to change. Work
which I'd rather avoid. Yet seeing thid makes me a little
uncomfortable. At the same time, I know it's worked all these years
so why am I even bothering to worry.

Is there any real issues with this?
I know a lot about wiring, know the codes, and know this is wrong.
Yet, I am not sure just what problems could be caused by this???

PS. I did think of one way I could correct it without digging up all
those wires, and that would be to use the single contact on the
pressure switch to (and the wiring) to run a low voltage into the
shed, then that low voltage would trigger a hefty relay that would
switch both sides of the 240V line, and be mounted in the shed. That
would be a bit complicated and costly but sure beats digging and
breaking up concrete.

But is any of this really necessary?????

(If I was not clear, the pressure switch is only turning off ONE of
the two 240V hot wires. The same way a light switch turns off the
kitchen light, except there is always one hot wire going into the well
that is never shut off, unless I turn off the well breaker.)

Mark