Well pump motor wiring


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Old 03-19-04, 07:08 AM
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Well pump motor wiring

I am rewiring my well pump. Motor is a GE 3/4 hp single phase jet pump set for high voltage. Currently wired to a 20 amp double pole breaker with 14 awg coded for hot. There is a plug-fuse enclosed switch for a disconnect, with one 25 amp and one 30 amp fuse. The motor is not currently grounded - previous owner just ran 2 wire cable. Motor is rated to pull 6.10 amps at 230v.

I have several questions, dumbest one first:

1. Why don't ac motors have a neutral line? Doesn't the breaker need to be tied to the neutral bus bar?

2. Is the 20 amp double pole the proper way to go?

3. Shouldn't the plug fuses also be 20 amps each so they match the 12 awg romex and the breaker?

4. Is running 12/2+G romex proper if I code the neutral for hot (tape wrap) at both ends, and properly ground in the service panel and to grounding screw in motor?

5. Would I get more well water pressure if I installed a larger motor, or is well pressure a function of your pressure tank or other factors?

Thanks for your help.
 
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Old 03-19-04, 07:48 AM
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1. Pure 240-volt appliances don't have a neutral line because they have absolutely no use for it. Electrons come in on one hot wire and go out on the other, and would just sneer at that neutral as they went past.

2. No, probably not. What do the installation instructions say?

3. What 12-gauge wire? What fuses?

4. Yes. But you mean code the "white" wire for hot. As previously discussed, there in no "neutral".
 
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Old 03-19-04, 08:16 AM
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14 gauge should be protected by a 15 am breaker and/or fuses.
 
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Old 03-19-04, 08:25 AM
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The circuit breaker should be a 15 amp breaker. 14 gauge wire cannot be on a 20 amp breaker.

The fuses should both be 15 amp fuses, matching the breaker.
 
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Old 03-19-04, 08:26 AM
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Follow up

John -

Thanks for the reply.

1. The 240v explanation makes sense.


2. No instructions available for pump. Isn't it safe to assume that 12 awg wire and a motor wich pulls just over 6 amps would be protected by a 20 amp breaker? I just don't know.

3. There is a switch disconnect mounted between the breaker and the pump. The 12 awg is running from OPD to disconnect switch, and then from disconnect to motor. I was going to replace the romex, and put THHN in flexible metal conduit running from disconnect to motor.

4. Yes - code the white.

Thanks.
 
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Old 03-19-04, 10:05 AM
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2. No instructions available for pump. Isn't it safe to assume that 12 awg wire and a motor wich pulls just over 6 amps would be protected by a 20 amp breaker? I just don't know.


A 20 amp breaker is proper to protect 12 g wire. But your original post said the wire was 14 g.


More water pressure is not a function of pump size...it's a function of the setting of the pressure switch attached to the pump. The setting of this switch is also related to the pressure tank, the pressure of which can be adjusted to match your pressure switch. Water volume is a function of the pump size.

This sounds like it's becoming a plumbing thread. Email me off line at 9C7 at firehousemail dot com if you need more info.
 
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Old 03-19-04, 02:09 PM
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Guys, motor circuits are an entirely different animal.

Most, if not all, resi. well pump motors have integral overload protection. This thermal protection negates the need for the breaker (or fuse) to provide overcurrent protection. In motor circuits the breaker only needs to provide ground fault and short circuit protection. The breakers are not sized per the standard 14AWG - 15 Amp, 12AWG - 20 Amp, 10AWG - 30Amp, etc.

The fuses in the disco could be of any size as they aren't even needed since the 20 amp breaker is ahead of them.

For this motor, using a standard Inverse Time Breaker, 20 Amp is fine, though I doubt it would have any trouble starting on a 15. If it wouldn't start with a 20 you could go as high as a 25 Amp breaker.

If an Instantaneous Trip Breaker was used, it could be as high as 50 Amp.
 
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Old 03-20-04, 09:21 AM
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Bolted is right, motor starting current can be 4 to 6 times the running current. Short circuit & ground fault protection for motor circuits can be sized at 400% for inverse time breakers{loads of 100a FLA or less}.
 
 

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