Well pressure switch only shuts off one side of line

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
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I may not follow but 12-2 is all that is needed The pump is 240 And all pressure switches I've ever seen are 2-pole switches If its only shutting off one side replace it.IF two wires under 1 screw easy fix. IF IT is a single pole A new pressure switch would cost alot less about $15 for a 40/60
Spud
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Yes, it's 12-2 The pressure switch HAS two poles. Only one is being used. I was wrong when I said I would need to change to 12-3. What I would need is 12-4 (no such thing), so I would need TWO 12-2 cables going from the shed to the cistern.
To explain exactly what I now have. The 12-2 cable goes underground from the shed to the cistern. One wire carries the power OUT to the pressure sw. The other carries the SWITCHED power back IN.
To switch BOTH sides, I'd need another 12-2 (another IN and another OUT wire.
If this did not require digging and busting out concrete, it would be simple. Just add another 12-2 cable. It's all the digging and breaking out the wall of that cistern that makes it a major job.
(I wish they would have used conduit, then I could have just shoved another cable thru.)
I think I'll just leave it !!!!
Thanks to all who replied...............
Mark
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Its just wired wrong you DO not need 12-4 The wire coming in goes to the two outside screws The wire to the pump goes on the other two screws 4 screws 4 wires two in two out to the pump BOTH WIRES carries the power OUT there is no neutral on a 230 pump ground yes
Spud
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Ummmmmmmmmm...... Yes, I need FOUR wires... That WOULD be 12-4 (or two 12-2 cables). Two IN, (from the shed) Two OUT (returns to the shed because thats where the pump control box is) Then it goes back outside and to the well.
You're right about no neutral.
I'd only need one of the ground wires, but I'd twist them together anyhow.
Mark
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Just leave the wiring as it is. It is not an unusual practice to only disconnect one side of a 220 volt line to shut something off. If you need to work on the wiring you shut off the circuit breaker.
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And if you are concerned about the capacity of the switch, install jumper wires to the second pole of the switch

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snipped-for-privacy@UNLISTED.com wrote:

I'm no code mavin, but the only examples of switching just one side of a 230 volt circuit I can think of is when the "switch" is contained within the device being powered, as the thermostats in electric water heaters.

I like that idea, but it wouldn't *have* to be "low voltage", Mark.
If there's a neutral in the shed, (And I sure hope there is.) then you could run one side of the 240 (i.e. 120 vac to neutral) out and back to the pressure switch and then all you'd need is a double pose-single throw relay with a 120 vac coil to switch both sides of the 240 volt power going out to the pump.
Since your talking 12-3 wire that says to me that the motor running current is less than 20 amps, so the relay wouldn't have be a monster, just get one rated for "motor starting", for the size of your pump motor.
Those relays aren't very costly, and since you're concerned enough to be asking about it, you may not sleep well unless you change it over, I'd go for it.
Searching eBay for "motor starter" (using an exact term search.) brings up lots which would work, like this one:
http://tinyurl.com/7azjf
You'd just use two of the three poles of course.

Only your local electrical inspector can tell you that. <G>
Jeff
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Jeffry Wisnia

(W1BSV + Brass Rat \'57 EE)
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Why whats the neutral for and where on the pump do you connect this 120 not needed or used so run the wire then wire nut it at the pump??

Or this http://cgi.ebay.com/NEW-30-50-SQUARE-D-WATER-WELL-PUMP-PRESSURE-SWITCH_W0QQitemZ7565601948QQcategoryZ57013QQrdZ1QQcmdZViewItem

Yes
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Spud wrote:

One end of the 120 volt relay coil (located in the shed) would connect to neutral. The other end of that coil would receive 120 volts (from one side of the 240 volt supply) controlled by the pressure switch. If there's no neutral in the shed, then you couldn't use that scheme.

http://cgi.ebay.com/NEW-30-50-SQUARE-D-WATER-WELL-PUMP-PRESSURE-SWITCH_W0QQitemZ7565601948QQcategoryZ57013QQrdZ1QQcmdZViewItem
He's already GOT a pressure switch, why are you suggesting another one?

--
Jeffry Wisnia

(W1BSV + Brass Rat \'57 EE)
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He was saying to use the neutral to operate a 120V relay. The pump does not need a neutral.
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snipped-for-privacy@UNLISTED.com wrote:

How do you know that? The circuit breaker in the shed is the disconnect. The pressure switch is the controller.
Quote from NEC (2002) Section 430.84 (Need Not Open All Conductors.):
"The controller shall not be required to open all conductors to the motor."
"Exception: Where the controller serves also as a disconnecting means, it shall open all ungrounded conductors to the motor..."
Again, the pressure switch is not being used as the disconnecting means in this case.
There is nothing wrong with the way it is. It's not an uncommon practice.
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OK, if it's listed that way in the code, thats even better. Somehow I thought it was required, even though it works the way it is. In that case, I got one less job to do. I like that !!!! :)
Thanks
Mark
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This is Turtle.
Breaking one service line to 220 volt service is done all the time. If you break one you break both in this case.
TURTLE
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