Why Your Irrigation Pump Overheats and Shuts Down

Pump Drawing Excessive Amperage

A 1/2 HP Sta-Rite shallow jet pump (220 V) with a 20 ft elevation head was pulling 14.8–15.6 amps, exceeding the nameplate maximum of 13.4 amps. The motor's internal thermal protector shut it down after ~20 minutes.

Root Cause: Too Much Water Demand

Centrifugal pumps draw more electrical current as flow increases. The system was demanding 20 GPM from a 1/2 HP pump—more than the pump can efficiently deliver. The motor overloads, heats up, and trips its thermal protection.

Simple Test to Confirm

Install a gate valve on the pump discharge. Gradually close it to restrict flow while monitoring amperage. You'll see the current drop as flow decreases, proving the pump is overworked.

Solutions

• Reduce the number of sprinkler heads or switch to lower-flow nozzles on the zones served by this pump.
• If the well can support it, upgrade to a larger pump (e.g., 3/4 HP or 1 HP) matched to the system's flow requirements.
• Ensure the pump is not also supplying household water, which adds uncontrolled demand.

Matching pump capacity to system demand is essential for reliable operation.