I am going to try to wire a supply line for a submersible well pump. I
talked to the contract who will be installing the well and he said the pump
will need 220V. He also said that I should use12/2 romex.
I was under the impression that it is either 120V or 240V, the only
difference between the two is that the 240 had 2 120V hot wires going into
it. Is this the case, or is a 240 and a 220 the same thing? Also, will one
12/2 romex cable be enough? I've read that you cannot run romex in a pvc
conduit. I want to run it underground for about a 10-15 foot run, so what
should I use? Thanks in advance for all your help.
220V and 240V are the same thing.
If you run underground feeder cable (type UF romex),you won't need a
conduit. Just make sure you bury it deep enough.
You might want to run 12/3 instead of 12/2 so you would have an unused
neutral wire if you ever want to install a light out there. (Yes, I
know the pump should be on a dedicated circuit. But if there's a
neutral wire, you can tap one leg for a light and maybe even tap the
other leg for a convenience outlet and just don't tell anybody)
Another question I have is why do I only need 12/2? I thought that 240 is
simply 2 hot 120's, a neutral, and a ground. Using the 12/2, I would only
have enough wires for 2 hots and a ground, right? That is why I thought I
might need 12/3.
The pump only needs two hots and a ground (like a welder or water
heater.) Stoves and dryers need 2 hots and a neutral and a ground
because they have 120v timers and buzzers and lights and stuff in
addition to the 240v heating elements.
You might want to run a neutral for use later while you are burying wire.
Can't tell you what code is, but my deep well submersible pump does not use
Romex....it uses #10 individual wires from the pump switch on down. These
are wrapped & taped around the flexible pvc water pipe with plastic
"standoffs" every 20 ft. or so to keep the wires from rubbing on the well
240 is correct, though 230-220 is interchanged freely. Just depends on who
Romex is improper to put underground. The correct name is UF cable.
Personally for the distance I would run conduit. That way if something
happens later you have a race way to pull more wires. The size of the wire
should include the distance the pump is down into the well. You can use
this calculator to check the size of the conductors.
Motors draw a lot of current 6 times the running load when they start. Using
to small of a wire only puts stress on the motor which can cause it to fail
The pump should have a sealed cord not romex or bare wires doing down into
The cord is what protects the wire from the water which will eventually get
through most single wiring insulation, even romex. UF would resist for
US volatge is commonally referred to as; 110, 115 or 120, 220, 230 or 240.
All pump motors I'm familiar with will be called 230. Well cable (is not
Romex) does not come with a neutral. And I strongly suggest the use of
approved well cable rather than some other form of wiring. If you want
another circuit 'out there' run one separately instead of trying to get 120
off one of the legs to the pump motor.
If you have a 2 wire pump motor (no control box above ground) you need two
hots and a ground; called 12/2 w/grnd. If you had a 3 wire pump motor
(control box above ground) you need two hot, a start and ground, 12/3
w/grnd. The motors don't require the ground but all present day codes do. I
say 12 because that was mentioned. The size depends on distance and motor
The cable should be direct bury but can be installed in a conduit if
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