12/2 with no ground into 12/2 with ground?

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poka72

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Here's my situation. I live on a lake and there is a buried run of 12/2 with no ground running down to the lake. I need to tap into that 12/2 with no ground to extend to my pump. I tried this today with 12/2 with a ground but with no success, pump will not turn on. I tried making a ground by sticking wire into the ground to see if that would work but didn't, It only allowed me to read the voltages on the lines. For some reason i read 120V on the black and 90V on the white....does that seem right?? Any help would be greatly appreciated. The pump is new and works when i plug it in my outlet in the garage. Any help on switching that from 230V to 115V? There are four terminals, 1 2 3 4. Terminals 2 and 3 have black wires coming out of the motor with a ground.
Any help would be greatly appreciated.
Lee
 

Jadnashua

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If the motor is wired for 240, it won't work at 120, or if it does turn, you'll likely burn it up quickly. It may be able to run at 120 if you move jumpers. There's often a label showing this and if not, you should be able to find it on the manufacturer's site.

Keep in mind that if the motor can be switched to run on 120vac, 12g wire and the likely 20A circuit may not be enough to drive it. 20A at 240 is likely more than enough. P=VA, so when the voltage doubles, you can draw twice the watts. Me thinks you should run a new circuit for the pump, and while you are at it, it's not a bad idea to update the existing line to one with a ground so you can gain some safety margin.
 

poka72

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there is a switch in the motor and i have switched that to 115, now to move the jumpers, i guess i'll have to figure that end of it out. Do you have any idea about the 12/2 wiring and a way to make that work?? There used to be a 2HP pump that the lady ran but I Just purchased a 1HP pump from the company that installed my well and they told me it would be sufficient for what I am using it for. I do not feel like running new wire because that would mean purchasing and burying 250' of it. The old wire is in good condition.
 

Lightwave

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There are too many variables to give you a 'step by step' guide at this point.

Voltage readings aren't necessarily meaningful when using an improvised ground. Try measuring the voltage between the two wires of your 12/2. You should get either 120 or 240.


To do this safely and legally you'll probably have to run a new cable (with ground) from the breaker panel.
 

Cacher_Chick

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The pump does not require a ground conductor to work, but code requires the circuit to have a ground running from the pump back to the panel. The fact that you don't "feel like" running a new wire does not make it ok to do a hack job.
 

hj

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Connecting a 12/2 w/ground to a 12/2 less ground does NOTHING to alter the electrical voltage. You have a different problem if the pump works from the original wiring but not when you add to it, or if the voltages read different at the two locations. How are you measuring the voltages at the two wires if there is no ground to act as a neutral?
 
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