Pool Motor Overheating - High Amps

[captjake]

Thanks for your input, but I'm not ready to run 75' of wire through the attic only for a test at 240V. For now, I want to concentrate on fixing the problem at 115V.

This setup has been in place for 7 years. There is no damage to the wire from the main panel to the timer.

Pump pressure is about 10.

[Allen G Myerson]

You don't have to go through the attic. Just run the wires directly from the circuit breaker to the pump via the easiest and most direct route. You will remove them after the test.

At least try a bench test at 240 volts near the circuit breaker like you did with 120 volts.

I'm thinking that this could be a problem with your neutral wiring.

[captjake]

Attic is the shortest route. Panel and pump are on opposite sides of the property.

Just disconnected the timer and light transformer. Hard wired to the motor direct. Still drawing 19A at the motor under load.

If you're thinking the neutral is bad, where in the circuit do you think it is originating?

[Allen G Myerson]

For the neutrals, it could be on the supply side. Ask the power company to check to see if it's on the supply. If the supply is good, get an electrician to check your system.

Can you do a bench test at 240 volts?

For a 240-volt test under load, I'm thinking you could just run the wire through the house and out a door or window to get to the pump. It's just for the test, so it doesn't matter where it goes.

I'm not sure what is causing the problem. Checking the current draw at 240 volts would help diagnose the problem. If you use much less total power (volts x amps) at 240 volts, then that would indicate a problem with the neutral.

Does the pump sound like it's running properly or does it sound like it's straining?

Are you having any other electrical problems? Things like lights flickering, or increasing or decreasing in brightness?

[Allen G Myerson]

Also, if you're going to rewire, I recommend that you switch over to 240 volts. It's better to run larger appliances at 240 volts to better distribute the power loads. You want to reduce the use of the neutral as much as possible.

[captjake]

Can I still run 10 awg for a 240V setup. If I'm going to spend money on this, I want to do it once and correctly.

What size breaker will I need for the 240V hook in?

[Allen G Myerson]

Running on 240 volts requires less current than using 120 volts. Therefore, you can use a smaller wire size for 240 volts than you would use for 120 volts.

A # 12 should be sufficient for 240 volts. I would go to # 10 for 120 volts. # 10 is a larger wire and would handle either 120 volts or 240 volts.

What else will be on the same circuit, and how much current will it require?
What is the one-way distance?

If only the pump will be on the circuit, and the circuit (one way) is less than 100 feet, you could use #12 with a 15-amp breaker, or #10 with a 25-amp breaker for 240-volt service.

If you want to run other things on the same circuit, then you will need to recalculate based on the total current load.

General notes:

1) Smaller wire size numbers indicate larger wire diameters.
2) Use copper conductors, not aluminum.
3) I am not an electrician. Get advice from a licensed, qualified electrician before deciding on what to do.

[Allen G Myerson]

If you currently have a wire size of # 12, then you should not have a circuit breaker larger than 10 amps for 120 volts. If you are running 20 amps and not tripping the breaker, then your breaker is either too big or defective.

The circuit breaker always needs to be sized equal to or smaller than the maximum allowable ampacity of the wires.

http://www.csgnetwork.com/wiresizecalc.html
http://www.gorhamschaffler.com/wire_siz ... lator.html
http://www.paigewire.com/pumpWireCalc.htm

[Rob W.]

If you currently have a wire size of # 12, then you should not have a circuit breaker larger than 10 amps for 120 volts. If you are running 20 amps and not tripping the breaker, then your breaker is either too big or defective.

The circuit breaker always needs to be sized equal to or smaller than the maximum allowable ampacity of the wires.

http://www.csgnetwork.com/wiresizecalc.html
http://www.gorhamschaffler.com/wire_siz ... lator.html
http://www.paigewire.com/pumpWireCalc.htm

This is incorrect. #12 CU is rated at 25 amps (NEC Table 310-16). It is more than sufficient for this application. If going to 240v, the ampacity will be lower, therefore the wire will still be fine. I would leave it a 120v.

As far as your problem, it sounds like it could be a bad neutral as stated earlier. This would either be at the power company transformer or main connection in your electrical panel. My advice is to hire an electrician to check this.

Rob

[Rob W.]

Also, a 20 amp breaker for this pump is the correct size. You could use a 15 amp but the Code allows a 20a (15Ax80%=12A, load is 12.6A so code says you can increase to the next standard size).

AND just because it doesn't trip with a 20 amp load does NOT mean it is defective.

[captjake]

Electrician and power company both here in the last week. Will call power company again. They are cheaper

[Rob W.]

Good luck! I know it is frustrating and wish I could help more, but without being there to see it....

[Allen G Myerson]

#12 CU is rated at 25 amps (NEC Table 310-16)

It's not that easy. You can't just say that # 12 is sufficient for 25 amps. You have to take into account things like temperature, voltage and length of run. The 25 amps would be a maximum, and you have to derate from there.

This reference shows that #12 is OK up to 25 feet for 20 amps at 120 volts. It shows that the wire size should go to # 10 for between 25 and 50 feet and to # 8 for between 50 and 100 feet. The poster's run is between 50 and 100 feet.

For 100 feet, 110 volt, 20 amps, single phase with a maximum voltage drop of 3 %, it shows that the correct wire size would be # 8.

Here is a reference that shows that for # 12 AWG, the maximum amps for power transmission = 9.3 amps

All three of the wire size calculators that I referenced show that the maximum ampacity of the # 12 at 100 feet at 120 volt is between 9 and 10 amps. That means that the maximum allowable breaker would be a 10 amp.

AND just because it doesn't trip with a 20 amp load does NOT mean it is defective.

I said that it was "either too big or defective". I did not know the breaker size when I wrote that. I now see that it is a 20-amp breaker. In my opinion, it is too big. IF it were a smaller breaker, then it would have to be defective.

It is my opinion that the wires are being overloaded with any current over 10 amps, at 120 volts. I would consider the integrity of the wires to be compromised. I think that they need to be replaced.

[Allen G Myerson]

CaptJake, what does the motor label say under "Amps" and S.F (Service Factor)? Amps should show two numbers, one for 120 volt (higher number) and one for 240 volt (lower number).

The pump is definitely using too much power. I think that it's probably using at least twice what it should be.

That is going to cost a lot in electricity.

I think that there is also a safety issue. Whatever is causing this could be potentially dangerous. If there is some sort of wiring problem, then it could potentially cause a fire.

I think that your pump problem should be solved by switching to 240 volts unless there is some sort of problem with the pump, motor or system.

Even if the motor problem is solved, I think that it would be smart to have the neutrals checked anyway to verify that they are good, as there is indication that there is possibly some sort of issue.

If you do switch over to 240 volts, you will need to change any switches to DPST (Double pole single throw). DPST switches cut both legs of the power.

I would go with the # 10 wire and a 25 or 30 amp breaker.

[captjake]

Hi Allen,

Thanks for sticking with me throughout the day. Your advice has been great.

The pump is running now, but still drawing high amps. I need to get some water moving or I'll have another problem. I will be in the attic this weekend to see if there are any damages to the wire.

I had an electrician at the house last week. He checked everything as OK. I'm calling the power company to double-check their stuff.

After that, I'll probably switch the motor and break setup to 220.