Pool Motor Overheating - High Amps

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captjake
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Pool Motor Overheating - High Amps

Postby captjake » Wed 01 Sep, 2010 15:58

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


Rob W.

Pool Motor Overheating - High Amps

Postby Rob W. » Wed 01 Sep, 2010 16:05

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

Pool Motor Overheating - High Amps

Postby Allen G Myerson » Wed 01 Sep, 2010 17:15

#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

Pool Motor Overheating - High Amps

Postby Allen G Myerson » Wed 01 Sep, 2010 18:50

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
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Pool Motor Overheating - High Amps

Postby captjake » Wed 01 Sep, 2010 18:55

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.
Rob W
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Pool Motor Overheating - High Amps

Postby Rob W » Thu 02 Sep, 2010 09:46

Allen,

Sorry if I offended you and I'm not trying to argue, but you are overthinking this and frankly your information is wrong. The calulation for voltage drop is based on the nameplate full load current which I the OP said on the first post is 12.6 amps. So, like I said before, the Code allows the use of a 20 amp circuit breaker. It also makes no difference what the voltage drop is, a 20 amp breaker is correct for #12 wire.

Capt Jake,

You can change it to 240v if you want, but it sounds like there is another problem and this may be just putting a band-aid on it. If you do decide to change the voltage, just get a 15/2 circuit breaker, move the hot from the 20 amp breaker to one pole and the neutral from the bar to the other pole and rewire the pump. Should be an easy change and will cost a few dollars. A 25 or 30 amp CB as mentioned is definitely too big. Also, as Allen metioned, you will need to change out any switches to double pole.

Rob
Allen G Myerson

Pool Motor Overheating - High Amps

Postby Allen G Myerson » Thu 02 Sep, 2010 13:34

Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper.


20 amp is the maximum allowable circuit breaker that can be used on 12 AWG. So, perhaps it is fine for this application.

Rob W
A 25 or 30 amp CB as mentioned is definitely too big.

The 25 or 30 amp CB was suggested if the poster replaced the wires with 10 AWG. A 25 or 30 amp breaker would be correct for 10 AWG wire. That would allow for the pump and for other equipment if necessary.
Rob W
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Pool Motor Overheating - High Amps

Postby Rob W » Thu 02 Sep, 2010 14:03

Allen G Myerson wrote:20 amp is the maximum allowable circuit breaker that can be used on 12 AWG. So, perhaps it is fine for this application.

Rob W
A 25 or 30 amp CB as mentioned is definitely too big.

The 25 or 30 amp CB was suggested if the poster replaced the wires with 10 AWG. A 25 or 30 amp breaker would be correct for 10 AWG wire. That would allow for the pump and for other equipment if necessary.


You still size the breaker based on the load not the wire size. It just cannot be rated higher than the conductor's ampacity. The pump should be on a dedicated circuit and the GFCI breaker should also protect the equipment not just the wire.
Allen G Myerson

Pool Motor Overheating - High Amps

Postby Allen G Myerson » Thu 02 Sep, 2010 20:25

Rob W
If you do decide to change the voltage, just get a 15/2 circuit breaker, move the hot from the 20-amp breaker to one pole and the neutral from the bar to the other pole and rewire the pump.

I also thought about advising the poster to do this. However, I had a few concerns:
1) I think that there is some question about the integrity of the wires.
2) Without seeing the job, I would be concerned that the neutral might be tied in together with other neutrals somewhere.
3) Using the white wire for power would go against the color convention. I suppose that the wire could be colored to indicate the new designation.
Rob W
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Pool Motor Overheating - High Amps

Postby Rob W » Thu 02 Sep, 2010 20:45

Allen G Myerson wrote:
Rob W
If you do decide to change the voltage, just get a 15/2 circuit breaker, move the hot from the 20-amp breaker to one pole and the neutral from the bar to the other pole and rewire the pump.

I also thought about advising the poster to do this. However, I had a few concerns:
1) I think that there is some question about the integrity of the wires.
2) Without seeing the job, I would be concerned that the neutral might be tied in together with other neutrals somewhere.
3) Using the white wire for power would go against the color convention. I suppose that the wire could be colored to indicate the new designation.


1) I agree it is possible the wire could have somehow been damaged.
2) Highly unlikely. This is rarely done in a house. You should not share neutrals in a dwelling unit. It does need to be confirmed, though.
3) It doesn't matter in residential. This is standard and the white wire is also used for switch legs for lightingl.

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