I have a 220 volt 30 amp supply, via buried 2 live plus (bare) ground cable out to my well. I need 110 v there for water treatment equipment. Water treatment guys say they can put a subpanel on the existing cable and split out 220 for the well pump and 110 for the other stuff. I don't know if this is a common practice, but it doesn't seem right to me to be using that ground wire as the neutral. Is this the right way to do it? What other options are there besides running a new cable? 220 to 110 Transformer?
I may be talking out of my a$$, but from my understanding, 220V is just 2
110V leads tied together (same phase of course). Thus splitting it would be easy (no transformer) and ground is ground. However ground is not neutral. I learned this the hard way when trying to figure out why a GFCI breaker I installed kept tripping. Turned out I was connected to the ground instead of neutral bar.
Using the ground as a neutral is very much a no-no in the electrical code. This is very much the wrong thing to do. Bare ground wires are NOT supposed to carry current except under fault conditions.
Code also doesn't like adding things onto motor circuits, so, if the pump really does need a circuit that big, you'll have code difficulties with adding a transformer, even if you subpanel it. (30A or even 20A at 240V is a big pump. So maybe you have plenty of headroom)
Then there's issues on how to wire the secondary side of the transformer w.r.t. neutral/ground references. Waterproofing. Etc. I'd be highly suspicious of an tradesman installing a transformer if he thinks using a ground wire as a neutral is a good idea.
Not insurmountable, but... It may be an expensive transformer depending on how much power the water treatment equipment needs. I don't like equipment like that outdoors if I can avoid it, nor would I trust _those_ guys to do it.
Another (remote) possibility would be to switch the pump over to 120V (assuming it was convertable, assuming it'd be okay on 30A), but that may (a) decrease the lifetime of the pump somewhat, (b) not have enough headroom for the extra equipment and (c) probably be a code violation (you can mark (identify) white wires black, but not the other way around).
I suggest you consult with an inspector and stress that running a new feed is "very difficult" or "very impractical" or words to that effect. Let the inspector suggest a solution.
Does the treatment equipment really have to be at the well head? I'd think for the most part it'd be MUCH easier to install it inside the building, where installing another circuit (or piggybacking on something else) would be vastly easier.
I think you are stuck with using a step-down isolation transformer, or water treatment equipment that is wired for 220V. (IMHO, water treatment equipment that designed to be situated outdoors or in a pumphouse should have its own 220v transformer as a built-in option)
Is the buried portion in conduit? Maybe you could add a white wire to the existing circuit.
Is the well in a building or out in the open? If it's in a pumphouse, what did you do for a light?
Do you have a metal well casing, or plastic?
Hey Chris, If the well is in a pumphouse, would that qualify as a separate building, and the existing 3 wires could be converted to a 240/120V
3-wire outdoor feeder if that subpanel the water guy mentioned was rated for service equipment? Or are 240/120V 3-wire feeders only for overhead wiring?
Not really OT here but I had a similar situtation. 220 pump and wanted a 110 utility outlet at the well head. Installers ran a 4 wire for the pump and a second 3 wire for the 110 (about 150 ft each). I asked why they couldn't just tap off one of the hots for 220 to get the 110. I didn't really understand the answer as to why they couldn't do that.
By and large, the NEC (and CEC) insists on dedicated circuits for devices with motors (say, about 1/4HP and up), or at least, not sharing it with general utility outlets. Ie: force-air furnaces and water pumps. Even if they're the same voltage.
Ie: you do this, and plug in a lawn mower. You're mowing the lawn, the pump kicks in, and you trip the breaker.
Secondly, except for "single devices" (like stoves and dryers), the NEC/CEC forbids sharing the same circuit between 120V and 240V loads. Even with split 240V/120V circuits (eg: kitchen counter outlets in Canada).
In order to make it "legal", they would have had to turn the 240V circuit into a subpanel feed, and install a subpanel at the wellhead, with separate breakers for the pump and outlet. By the time you factor in subpanel installation, weatherproofing, etc, using a separate circuit for the utility outlet is cheaper and vastly less trouble in the long run. A few 10s of bucks worth of underground wire versus $100+.
Secondly, you mention a 4-wire 240V pump circuit. A 240V pump only needs two hots and a bare ground. Having it 4-wire suggests to me that it's a submersible pump with the control box inside the house. You can't tap a utility outlet off that, regardless of electrical code. You don't _have_ 120V at the pump (except relative to the ground, and you can't do that)... The fourth wire is actually a start winding in the pump motor, not a neutral.
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