Myers pump tripped the circuit breaker. Perplexing situation

[Solomon]

Hi every body. My outdoor submersible 4/10 HP 15 years old Myers pump tripped the circuit breaker several times before I removed its plug from the dedicated outlet in the sump well and put it on a 100 feet extension cord connected to my garage outlet. It worked for several weeks with no problems. After replacing the dedicated receptacle and circuit breaker, I tried connecting the pump again to its original outlet. The pump works, but with a rattling noise ,and surprisingly, when back to the extension cord it works smoothly with no noises or trips. The multimeter reads 120 volts on the outlet. What's going on here?
I appreciate your comments .

 

[Paulypfunk]

Do you have a clamp style multimeter where you can check amperage draw?

 

[Sponsor]

 

[Paulypfunk]

I’m wondering if your wiring has a short in it somewhere and the restriction is causing the rotor to spin at a lower speeds, causing the noise. A different amperage reading between the outlet and the ex cord might confirm this. Maybe you have a damaged wire between the breaker and the outlet?

 

[Solomon]

Hi every body. My outdoor submersible 4/10 HP 15 years old Myers pump tripped the circuit breaker several times before I removed its plug from the dedicated outlet in the sump well and put it on a 100 feet extension cord connected to my garage outlet. It worked for several weeks with no problems. After replacing the dedicated receptacle and circuit breaker, I tried connecting the pump again to its original outlet. The pump works, but with a rattling noise ,and surprisingly, when back to the extension cord it works smoothly with no noises or trips. The multimeter reads 120 volts on the outlet. What's going on here?
I appreciate your comments .

I’m wondering if your wiring has a short in it somewhere and the restriction is causing the rotor to spin at a lower speeds, causing the noise. A different amperage reading between the outlet and the ex cord might confirm this. Maybe you have a damaged wire between the breaker and the outlet?

 

[Solomon]

Thank you so much Paulypfunk. I'm going to get one and I'll post the results. Have a great day!

 

[Paulypfunk]

Just spitballing here. Let us know what you find out. I’m curious.

 

[Solomon]

Hi Paulypfunk and Thank you very much for your concern. Unfortunately,I was busy with my son's medical issue in these two days. I'll do the test tomorrow and will post the results. Thank you again and hail to curiosity and perseverance!
Solomon.

 

[Solomon]

Hi. I did this today using CL390 KLEIN TOOLS clamp multimeter. While set to 40A position, it reads 00.03 ~00.04 when not clamped to any source . When I clamped it around the ex cord while pump running, it read 00.12 ~ 00.13. When I plugged the pump to dedicated outlet, it read 0030 ~00.40 and the circuit breaker tripped in maybe less than 5 seconds. I noticed that there were two pairs of wires coming to the box under this "in the well outlet", one has never been used judged by intact cut ends, the other connected to the receptacle. What does all this mean and what should be done next. My best regards in advance.

 

[Reach4]

Hi. I did this today using CL390 KLEIN TOOLS clamp multimeter.

When using a clamp ammeter, it is important that the clamp only go around one conductor. If you go around a cable with a hot and ground, the magnetic field will cancel, and you will read a net near zero, as you did.

The pressure switch may be a good place to grab around a single conductor.

If nowhere else, you can probably go around that hot inside the breaker panel with the cover off.

 

[Solomon]

I repeated the test using the above setting. I got 8.70 Amps with both extension cord and the outlet. To my more amazement, and maybe out of luck, the pump worked fine with no extra noises or fuse trips while it was on dedicated outlet and this piece of wire.Problem got more perplexing?
Is this amount of current normal for such a pump?

 

[Solomon]

The pressure switch might be a good place to grab around a single conductor. Maybe you have a damaged wire between the breaker and the outlet?

The fact that there is similar ammeter readings doesn't exclude that possibility?

 

[Reach4]

I got 8.70 Amps with both extension cord and the outlet.

For comparison, a 1/2 HP 115v Franklin pump draws 10.0 amps at "full" load and 12.0 at maximum load. So your 4/10 HP sounds like it is in the ballpark.

 

[Fitter30]

Are wires at the receptical stabbed in the back or wrapped around the screws? If stabbed wrap them around the screws.

 

[Solomon]

Are wires at the receptical stabbed in the back or wrapped around the screws? If stabbed wrap them around the screws.

Thank you all for your comments. When I replaced the receptacle with a new one, I wrapped wires around the screws. Based on Reach4 comment, amperage should be ok for both extension cord and the receptacle. What should be done next? I will hook up the receptacle to the other "free" wire and see what happens.

 

[Reach4]

Hi every body. My outdoor submersible 4/10 HP 15 years old Myers pump tripped the circuit breaker several times before I removed its plug from the dedicated outlet in the sump well and put it on a 100 feet extension cord connected to my garage outlet.

I’m wondering if your wiring has a short in it somewhere and the restriction is causing the rotor to spin at a lower speeds, causing the noise.

Intermittent short? Maybe wiggle stuff, and see if you can blow that breaker again.

 

[Solomon]

I checked the pump plug with ohmmeter and found out that there were continuity around 4 ~5 ohms between all three prongs, suggesting some kind of short circuit in the pump itself or the cables/plug . Now I can figure out why pump works fine on ungrounded extension cord but blows breaker when hooked to grounded plugs like the dedicated outlet.
Now Could I hook the pump up with an ungrounded extension and leave it , or change its plug ,or open the pump for further trouble shooting?
When on ungrounded ex cord ammeter would read ~8Amps and when on grounded it reads ~5 Amps.
Your comments are most appreciated.

 

[Reach4]

I checked the pump plug whit ohmmeter and found out that there were continuity around 4 ~5 ohms between all three prongs, suggesting some kind of short circuit in the pump itself or the cables/plug

Good going.

With a short to the case, I would replace the pump.