36 Well Pump Failures

Lightning is not the only reason well pumps fail. Like all appliances, well pumps eventually succumb to age and wear. One of the more common ways for a well pump to fail is for the windings in the electric motor to simply wear out.

When an electric motor begins to fail, it consumes more electricity than normal and operates at a higher temperature. As the motor further degenerates, the operating temperature of the motor rises until the dielectric within the motor windings breaks down and a short within the windings occurs. This causes the electric motor to "ground out." It is notable that some service persons will cite that a "grounded out" motor is evidence of lightning damage. This is not exactly true. What is true, is that "grounded out windings" are a symptom common to both lightning and normal motor failure.

When aboveground electric motors, such as window fans, begin to fail, usually the motor casing feels hot, perhaps a slight electrical odor is noted, and when started, the fan hesitates, taking longer to reach operating speed. Unfortunately, because well pumps are located underground, these same symptoms will not be noted by the owner. This is why it is often a total surprise to the owner.

Some well pump motors have a temperature sensor within the windings. When the temperature of the windings becomes too high, a switch opens the circuit and turns off the motor. This is an indication that the motor is near the end of its life and will soon fail. However, when the motor windings cool back down, the switch will often be of the type that resets, and the motor will operate for a time again. Unfortunately, this type of behavior in the motor is also rarely noted by the owner due to the location of the equipment.

However, some of the symptoms that clearly indicate routine failure by wear and age in a well pump include the following:

• worn motor bearings (rotor shaft is hard to turn, or does not freely spin).

• water leakage into the motor housing and windings.

• worn pump impeller bearings.

• worn packing around bearings and shaft allowing silt to get into bearings and internals.

• discoloration of the internal lubrication oil (if any) due to operation at elevated temperatures.

Plate 3.2 Surge damage due to loose utility cable that fell onto lower line and caused high voltage surge. Initially diagnosed as lightning damage.

• deteriorated relays due to higher than normal operating currents, or higher than normal duty cycling.

• widespread deterioration of dielectric in windings by overheating (instead of a single, breakthrough point of damage like lightning makes).

• higher than normal electric bills (when accurate comparisons can be made), unusual tripping of breakers, or other items that indicate higher than normal current usage.

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