Cable Size for Deep Well Submersible Pumps
The cable feeds a motor that may be hundreds of metres down, and every metre adds resistance. The recommended sizes below come from our QJ range. Within each band the exact size depends on the model, so check the line for your pump in the selection table. They are a starting point for normal lengths.
| Motor power | Rated current (approx.) | Recommended cable |
|---|---|---|
| 0.75 to 1.5 kW (100QJ) | 2 to 3.8 A | 3×1.5 + 1×1 mm² |
| 2.2 to 3 kW (100QJ) | 5.6 to 7.3 A | 3×1.5 + 1×1 to 3×4 + 1×2.5 mm² |
| 4 to 7.5 kW (100QJ) | 10.3 to 18.5 A | 3×2.5 + 1×1.5 to 3×6 + 1×4 mm² |
| 3 to 5.5 kW (150QJ and up) | 7.8 to 13.7 A | 3×4 mm², some deep models 3×6 |
| 7.5 to 13 kW | 18 to 30.9 A | 3×4 to 3×6 mm², 3×10 for some high-head models |
| 15 to 22 kW | 35 to 50 A | 3×6 to 3×16 mm² |
| 30 kW | about 65 A | 3×16 to 3×25 mm² |
| 37 to 45 kW | 80 to 97 A | 3×16 to 3×50 mm² |
When to go one size up
- The cable is long: the pump is deep, or the control panel is far from the well
- The supply voltage at site is already on the low side
- The pump will start often
A cable that is too thin lets the voltage at the motor fall. The motor then draws more current, runs hot and trips. Measure the voltage at the panel with the pump running; for a 380 V supply it should stay roughly between 360 V and 400 V.
Tell us the setting depth and the distance from the well to the panel, and we will size the cable with the pump.
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