A borehole pump is a significant investment, often buried tens of meters underground. When it burns out, you’re not just facing the cost of a new unit—you’re looking at the labour-intensive “pull and replace” process.
Most pump failures are preventable. By understanding the common enemies of submersible motors, you can ensure your water flows reliably for years. The following are the most common causes that cause most pumps to fail:
Dry Running
The most common cause of motor burnout is dry running. Submersible pumps rely on the water passing through them to cool the motor. If the water table drops below the intake, the motor will overheat in minutes.
- The Fix: Install a Full Protection VSD (Variable Speed Drive), stainless steel borehole float switch or dry-run protection relay. These devices detect a drop in current (which happens when the pump is spinning air instead of water) and shut the system down before damage occurs.
Stabilize the Power Supply
Pumps are sensitive to electrical fluctuations. Voltage surges (lightning strike or grid spikes) can fry the internal windings, while voltage drops (brownouts) force the motor to draw more current to stay at speed, leading to overheating.
- The Fix: Use a dedicated Pump Control Box with built-in surge protection and under/over-voltage monitoring, if it doesn’t have one, couple it with an external surge protector. More ideally, use a Variable Speed Drive (VSD), it ensures a “soft start,” reducing mechanical stress and electrical spikes.
Watch for Sand and Sediment
Abrasive sand can act like sandpaper on the pump’s internal impellers. If the impellers lock up due to debris, the motor will enter a “locked rotor” state, drawing massive amounts of current until the insulation melts.
- The Fix: Ensure your borehole is properly “developed” and cleaned before installation. During installation of pump, do not place pump smack at the bottom of the shaft, ensure it hangs at least 2 meters from the bottom.
So, preventing a burnout isn’t about luck; it’s about layering your defences. A combination of electrical monitoring, mechanical maintenance, and dry-run sensors will turn a fragile system into a resilient one.
Don’t leave your water security to chance – visit our shop today to explore our range of quality pumps and protection systems or sit down with our expert technicians for a personalized consultation to future-proof your borehole
