Pump Plug is HOT

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kafox001 said:
Are these the correct plug and power cord for this application?
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Yes.

kafox001 said:
I also found this power cord from Pentair, but can't really find it from any reputable sellers. Would this also work?
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No. It is a 15amp cord with a 15 amp plug.

kafox001 said:
Any other concerns with the setup as a whole provided I can get the appropriate power cord? Thanks
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You are pushing the limits and need to keep an eye on the pump wiring and connection for signs of overheating. 17.7 amp load on a 20 amp circuit exceeds the NEC 80% load factor limitation. Yeah, I know this is a VS motor that should not be pulling 17.7 amps at low speeds but the 15A plug overheating shows more is going on. No major pump manufacturer would sell the pump and motor combination you constructed with a 15A or 20A plug in cord. So you are in a experimental situation that you constructed.
 
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ajw22 said:
You are pushing the limits and need to keep an eye on the pump wiring and connection for signs of overheating. 17.7 amp load on a 20 amp circuit exceeds the NEC 80% load factor limitation. Yeah, I know this is a VS motor that should not be pulling 17.7 amps at low speeds but the 15A plug overheating shows more is going on. No major pump manufacturer would sell the pump and motor combination you constructed with a 15A or 20A plug in cord. So you are in a experimental situation that you constructed.
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The pump is only running at full speed because its the beginning of the season and I'm trying to clear up the cloudiness - the majority of the year it does not run at full speed.

What is the appropriate breaker size and plug for this motor?
 
kafox001 said:
The pump is only running at full speed because its the beginning of the season and I'm trying to clear up the cloudiness - the majority of the year it does not run at full speed.

What is the appropriate breaker size and plug for this motor?
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20% more than the max current load. So 22 amps minimum.
 
I would not have a problem running 17.7 amps on a dedicated 20 amp plug/receptacle/GFCI breaker (89% capacity) but many here do since it does not meet the 80% rule.
Again i would also not have a problem putting on a 30 amp plug/receptacle on 12 AWG conductors to your existing panel. Your breaker is designed to protect your wiring from failing and starting a fire.

But then again i do all my own wiring and my buddy who is IBEW knows what i am doing and he swims in my pool.

I would do as stated above and use switch on pump controller.
 
Darin said:
But then again i do all my own wiring and my buddy who is IBEW knows what i am doing and he swims in my pool.
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You’re buddy knowing what you did on your home is very different than what would happen to him if he did that on a customers job and was caught. 😉

Why not just do it right? That way when the house is sold to a new owner, someone who doesnt know about the janky electrical job doesnt have to curse the previous homeowner for installing an outlet that says its rated for 30A but only has a real life capacity of 20A. On top of that, most 30A sockets accomodate 10AWG wire at the smallest and so someone else hooking up equipment would assume it’s at least wired with the rated wire size.
 

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Darin said:
I would not have a problem running 17.7 amps on a dedicated 20 amp plug/receptacle/GFCI breaker (89% capacity) but many here do since it does not meet the 80% rule.
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In my opinion, the actual amperage will not exceed 14.5 amps.

The 17.7 amps is for minimum circuit ampacity.

Measure the current with a True RMS clamp ammeter if you want to be sure.

Assuming a 75 C rated wire, the smallest wire you can use is 14 gauge.

Using 15 amps as the actual current, you have to limit the wire length to 44 feet (14 AWG), 69 feet (12 AWG) or 114 feet for 10 AWG.

If your voltage drop is 3.6 volts, then you lose 54 watts in the wiring at 120 volts at 15 amps.

For 240 volts, the voltage drop will be half at 1.8 volts and the current will be half at 7.5 amps, which means that the power lost in the supply wires is 1/4 at 13.5 watts.

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JamesW said:
In my opinion, the actual amperage will not exceed 14.5 amps.

The 17.7 amps is for minimum circuit ampacity.

Measure the current with a True RMS clamp ammeter if you want to be sure.

Assuming a 75 C rated wire, the smallest wire you can use is 14 gauge.

Using 15 amps as the actual current, you have to limit the wire length to 44 feet (14 AWG), 69 feet (12 AWG) or 114 feet for 10 AWG.

If your voltage drop is 3.6 volts, then you lose 54 watts in the wiring at 120 volts at 15 amps.

For 240 volts, the voltage drop will be half at 1.8 volts and the current will be half at 7.5 amps, which means that the power lost in the supply wires is 1/4 at 13.5 watts.

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He’s already burning up 15A sockets and plugs.
 
The CYA is follow the manufacturers instructions and follow code requirements. They are both there is ensure safe operation and safe failures.

Circuit breakers and fuses are to protect downstream wiring and devices. Installing a 30A plug that is protected by a 20A breaker is potentially problem prone as it can cause nuisance tripping of the breaker. It's also not allowed by NEC. 20A breakers can be damaged from the higher current that a 30A device can draw. A short circuit in a device intended to be used on a 30A circuit can draw much more current than short circuits in a 20A device. It seems like using over rated plugs and receptacle is more robust, but it's not always the case. Are you going to correct these for the next owner of your home?

Another example oversizing isn't always good. Towing a 5th wheel camper with 3/4 and 1 ton pickups is fine. Tow a 5th wheel camper with a semi that is intended to tow 50K-60K trailers and it will likely damage the 5th wheel camper over time. Not an apples to apples comparison, but there are many nuances in the NEC and UL codes for very specific reasons (many because of things being learned the hard way).

The wire gage required to carry a load is dependant on many things. Wiring in a building or structure is minimum 14 awg for 15A circuits, 12 awg for 20A circuits. The wire in a piece of equipment or the line cord powering the equipment can be a smaller gauge, that is because the mfg of the equipment has tested it and has also have the equipment tested by UL (or some other certifying lab) to make sure it's safe when operating and when there is a failure in the device. Many devices have thermal switches, fuses, breakers, etc) that will limit the amount of time a device can drawn a high current. This is how a smaller gage wire is protected from turning into the fuse.
 
Bperry said:
He’s already burning up 15A sockets and plugs.
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The minimum circuit ampacity is based on the 17.7 amps.

So, the smallest circuit breaker would be 20 amps.

The wire, switches, plugs etc. need to be rated equal to, or greater than, the circuit breaker.

15 amps is not acceptable for any component.

I would not use a plug in any case.
 
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Bill1974 said:
Installing a 30A plug that is protected by a 20A breaker is potentially problem prone as it can cause nuisance tripping of the breaker. It's also not allowed by NEC.
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The plug has to be rated at 20 amps or higher if the breaker is 20 amps.

So, a plug rated at 30 amps is fine.

The maximum continuous load should be less than or equal to 80% of the breaker rating.

80% is 16 amps.

In my opinion, the pump is not going to exceed 16 amps.
 
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The original issue is the plug was being used as a switch (unplugging under load). I would bet that the manual for the pump states that it should be hardwired and not use a plug and receptacle (because of this issue, what code permits and what plugs and receptacles designed for). This would eliminate arcing on the plug. If it was hardwired it also gets past the 80% limit.

From the 2023 NFPA 70 NEC:
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JamesW said:
In my opinion, the actual amperage will not exceed 14.5 amps.
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The Neptune is listed as 13.6 amps, which is probably more realistic than 17.7 amps.

Typically, a motor will pull about 1,000 watts per hp.

At 1.65 HP, the watts will be 1,650 and the amperage at 115 volts will be 1,650/115 = 14.35 amps.

In any case, the minimum ampacity has to be equal to or greater than 17.7 as specified.

Continuous loading of components is usually limited to 80%, so a 15 amp plug should be limited to 12 amps and this only applies up to 86 degrees Fahrenheit.

If the plug is in an ambient temperature higher than 86 degrees, you have to derate the plug accordingly.

At 114 Degrees F, the plug, wires and all components should be derated at 75%.

So, a 15 amp plug at 114 degrees should not be loaded more than 15 X 0.75 X 0.80 = 9.00 amps continuous load.

If a switch or plug is in the sun, it can easily exceed 114 degrees.

In places like AZ, the ambient can exceed 110 degrees and being in the sun can further increase the temperature to over 130 degrees.

In addition to ampacity, you have to limit the voltage drop to 3% on the supply wires.

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Bill1974 said:
The original issue is the plug was being used as a switch (unplugging under load).
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Plugging and unplugging a pump under load using the plug as a switch will damage the plug and this is not an acceptable way to switch power.

Arcing will burn the plug and cause excessive resistance and further damage to the plug terminals.
 
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Bill1974 said:
Installing a 30A plug that is protected by a 20A breaker is potentially problem prone as it can cause nuisance tripping of the breaker. It's also not allowed by NEC.
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Q. What are the NEC requirements for sizing receptacles?

A. A single receptacle on an individual branch circuit must have an ampacity not less than the rating of the overcurrent device [210.21(B)(1)]. Note: A single receptacle has only one contact device on its yoke [Art. 100]; this means a duplex receptacle is considered two receptacles.

If a receptacle is connected to a branch circuit that supplies two or more receptacles, the total cord- and plug-connected load must not exceed 80% of the receptacle rating [210.21(B)(2)]. A duplex receptacle has two contact devices on the same yoke [Art. 100]. This means even one duplex receptacle on a circuit makes that circuit a multi-outlet branch circuit.

According to 210.21(B)(3), if the receptacle is connected to a branch circuit that supplies two or more receptacles, the receptacles must have an ampere rating in accordance with the values listed in Table 210.21(B)(3), as shown at the right.

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www.ecmweb.com

Stumped by the Code? Sizing Receptacles, Wiring Under Roof Decking & More

Your most pressing National Electrical Code (NEC) questions answered
www.ecmweb.com www.ecmweb.com
 
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Just wanted to give an update. I replaced the cord with a 12awg nema 5-20P cord and the plug is no longer overheating. Everything seems to be working as it should but I'll keep an eye on it.

Appreciate all the conversation and will plan for a 240V circuit upgrade at some point in the future.
 
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