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Old 03-31-2014, 10:47 AM   #1
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new power to new pump


Hi there ,Im drilling a new well next week it is 140 feet from house, I will be using a 2 wire 220 volt submersible pump probably 1/2 horse and the wire will be under ground. What size and kind of wire should i use it will be in conduit.. And can i run the same wire down the well to the pump which should be in the 150 foot range. so from house to well and down to pump is approximate 290 feet . And do you know what size of breaker that would take.
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Old 03-31-2014, 11:01 AM   #2
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i would use a 10-2 wg uf .the wire in the well should be supplied by the well people.it will come out to the control box. the wire for the power will go in to the control box, then go to the pressure switch & then to the panel, i would use a double pole 20. the reason the 10 gauge is for voltage drop.

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Old 03-31-2014, 02:48 PM   #3
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Most Mfgs are going to call for a fused disconnect at the well location. In that case, I would probably use a 30 amp breaker at the source panel.
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Old 03-31-2014, 11:40 PM   #4
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If the pump motor is 1/2HP at 240 volts single phase, the largest breaker allowed by code is a 15 amp.

#14 is the smallest wire allowed by code, and if it is used, the voltage drop will be roughly 5 volts while running and 32 volts while starting. #12s would be 3 volts drop running and 18 volts while starting. #10s would be 1.5 volts running and 9 volts starting.

Since I don't know the area the well is in, I'd go with 12s. 14s might be ok, but if there are minerals in the water, the lower starting voltage will result in lower starting torque which might not be able to break the deposits that form on the bearings. Plus, the difference in cost of 12s vs. 14s is not all that much.

10s would be sort of ok too, but the more voltage a motor is started with the more mechanical shock it is subject to; this will shorten its life, but not by much. All electric motors are designed to start on less than full voltage.

If it were me, I'd run 3/4 PVC conduit rather than UF cable. This way if the pump is ever replaced by a larger one or by a 3 wire one, it'll be easy to replace the wire.

Might be a local thing, I don't know, but I've installed tons of well pumps (most of which are inspected), and have never seen one that had a disconnect at the well. Again, this might be a local thing, your area could be different.

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Old 04-01-2014, 01:45 AM   #5
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Quote:
If the pump motor is 1/2HP at 240 volts single phase, the largest breaker allowed by code is a 15 amp.
Code reference please.
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Old 04-01-2014, 06:34 AM   #6
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Even though you are installing a 2 wire pump, I would still run 4 conductors from the house to the well for future precaution, also, well drop cable is not allowed to be used from the well to the house even though every well guy does this, they just don't know the codes.

If you are installing a metal well casing, that must be bonded via the equipment grounding conductor, just drill and tap the casing and install your own lug.

15 amp 2 pole breaker is the largest breaker you can use on this application, I personally would use # 12 AWG conductors.

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Old 04-01-2014, 06:37 AM   #7
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Quote:
Originally Posted by Oso954
Code reference please.
4.9 amps is the full load current of a 240v 1/2 HP single phase motor, you are allowed to increase that by 250%, which equates to 12.25 amps, 15 amp breaker.

Table 430.248 is where you find full load currents.


We are only providing short-circuit and ground fault protection in this application, the over current protection is provided by the motor.

Also, no disconnect is required at the well head, I forget the code section, but when installing a disconnect that creates more of a hazard than a safety, they are omitted.

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Old 04-01-2014, 09:31 PM   #8
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I see alot of good ideas here thanks for all the help. A few guys recommend the 12 AWG will that be ok for the distance i have to go. I know its 140 feet or less from breaker to well. And well depth is in the 150 range. I would like to use the 12AWG if its big enough thanks for all the help.
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Old 04-02-2014, 10:05 PM   #9
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I would like to bury this line in conduit in case i ever have to pull other wire for some reason What size of conduit should i use to bury this line, Also wondering if the 12AWG will be big enough.
Thank all you guys for the good advice
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Old 04-02-2014, 11:43 PM   #10
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Quote:
Originally Posted by jkoepke
I would like to bury this line in conduit in case i ever have to pull other wire for some reason What size of conduit should i use to bury this line, Also wondering if the 12AWG will be big enough. Thank all you guys for the good advice

1" PVC, and #12 awg is fine.

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