Up to Speed

Residential August 2020

My single-speed swimming pool pump motor, installed in 2004, finally quit working. I nursed it along for many years and probably should have replaced it a long time ago. However, I kept finding other ways to spend the money. We all have that problem, occasionally, so I am not alone in trying to stretch an old piece of electrical equipment for longer than I should.

I had the motor rewound and rebuilt about six years ago, but my pool maintenance electrician finally said it was time. He asked if I wanted a single-speed motor or a variable-speed, state-of-the-art pool pump. I am amazed at the sophistication of new pool pumps.

The replacement is a high-efficiency, variable-speed, permanent magnet synchronous motor. This pool pump motor is designed with an automatic-frequency, speed-control system that operates at lower temperatures due to its high efficiency. Based on requirements in 430.126(A) and the informational note in this section, motor current and the frequency used for motor control may cause extra heat in the motor. The motor’s efficiency and high power-factor may help keep the temperature down. This motor has an active power-factor correction feature with automatic energy conservation. Additionally, due to the synchronous design, it helps provide power-factor correction for the motor.

It can be programmed to run at various speeds during the day or at a constant flow rate, depending on what the pool requires. The pump can operate from 450 rpm to 3,450 rpm with preset speeds of 750, 1,500, 2,350 and 3,110 rpm. Or the pump can be set to control its own speed to maintain a constant water pressure. This constant pressure is often necessary for pool-cleaning systems, such as in concrete pop-up heads and hose-connected cleaners, e.g., Polaris and similar systems. The pump pressure control can vary between 20 gallons per minute (GPM) and 140 GPM. The pump can be set for the desired GPM, depending on the accessories that are connected to the pump. It will maintain the desired GPM even as these accessories turn on and off.

There is a pump control panel and an alarm with LED control panel illumination and error messages to warn of improper pump operation. This control panel is usually located on top of the motor but can be moved to a remote location where the normal location of the pump motor is not easily accessed. In addition, the motor and its control panel can be connected by a communications port at the motor and control system by a two-wire port connection using an RS-485 connector. Like I said, these motors are extremely high-tech. In December 2019, I wrote about troubleshooting a refrigerator using a cell phone connection to the service center. These pool pump motors are in the same high-tech category as the refrigerator, as far as I am concerned.

Pool pump motor

When a swimming pool pump motor is changed out and a new pump is installed, don’t forget about connecting the bonding conductor to the replacement motor as required by 680.26(B)(6). If the pump motor is a listed double-insulated motor, there should still be a solid No. 8 copper conductor located near the motor. The reason for this solid No. 8 copper bonding conductor brought to the proximity of the double-insulated motor location is to ensure there is a bonding conductor in case the double insulated motor is removed and replaced with a regular metal motor.

Bonding the pool pump is particularly important to ensure there is not a difference of potential between any of the pool components so a person is not subject to spurious currents in and around the pool. In addition, when one pool pump is removed and another installed, all the pump components must be checked for proper size. For example, 430.6(A)(1) requires the full-load current of the motor, based on tables 430.247, 430.248, 430.249 or 430.250, to be used for the ampacity of the conductors, ampere ratings of any switches used in the circuit and the branch-circuit short circuit and ground-fault overcurrent protection. The nameplate rating of the motor is only going to be used for the full-load ampere rating to determine the motor’s overload protection.

Remember, changing out the pump motor is only the first part of the overall installation requirement. You must follow all the requirements in articles 430 and 680.

About the Author

Mark C. Ode

Fire/Life Safety, Residential and Code Contributor

Mark C. Ode is a lead engineering associate for Energy & Power Technologies at Underwriters Laboratories Inc. and can be reached at 919.949.2576 and Mark.C.Ode@ul.com.

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