Before you choose a borehole pump model, you must answer one basic question: what electricity do you actually have at your site? Supply conditions differ widely between countries, regions, and even individual project sites — so the answer must come from your own measurements, not from a country’s nominal standard. This guide explains the difference between single-phase and three-phase borehole pumps, how to choose for your site, and how to protect your pump from a difficult supply.
One important statement up front, because the search term brings many single-phase questions: our standard QJ/QJT borehole pump sets are three-phase. Single-phase applicability is not part of the standard range and must be confirmed case by case with our engineers. And a custom 220 V motor build does not automatically mean single phase.
The Basic Difference
A single-phase supply has one live wire and a neutral — typically 220–240 V. It is what homes and small shops use. A three-phase supply has three live wires — typically 380–415 V between phases. It is the usual supply for industry, agriculture, and water projects.
For electric motors, three-phase power has real advantages:
| Point | Single phase | Three phase |
|---|---|---|
| Typical use | homes, small plots | farms, projects, industry |
| Practical power range | small motors only | from a few kW to hundreds of kW |
| Starting | needs a capacitor or start circuit | starts strongly by itself, no extra parts |
| Running quality | more vibration and heat at higher load | balanced, cooler, more efficient |
| Cable for the same pump | thicker cable, higher losses | thinner cable, lower losses |
| Maintenance | capacitors are a common failure point | simpler motor circuit |
The bigger the pump, the more three-phase wins. That is why serious borehole pumps are built around three-phase motors. Our QJ/QJT range, for example, covers motors from 3 to 250 kW on a standard 380 V ±5%, 50 Hz ±1% three-phase supply.
Know Your Real Supply Conditions
On paper every country has a standard voltage and frequency. At the project site, conditions can differ from the paper:
- Long rural lines can mean significant voltage drop at the end of the line, especially at peak hours.
- Three-phase networks may be 380 V or 415 V depending on the country and utility — the two are not interchangeable for a motor.
- Voltage fluctuation is common on long or heavily loaded lines. Low voltage makes motors draw more current and overheat. A lost phase on a three-phase motor can burn the winding in minutes.
- Some countries use 60 Hz — for example Liberia. A pump motor built for 50 Hz cannot simply be plugged into a 60 Hz grid.
A motor is built for a specific voltage and frequency, within a tolerance. Ours is specified for 380 V ±5% and 50 Hz ±1%. Anything outside that needs attention — either supply correction or a custom-built motor. Always work from your project’s actual supply data: measure it, or get it in writing from the utility.
How to Choose: Single Phase or Three Phase
Use this simple logic:
| Your situation | Recommended choice |
|---|---|
| Only single-phase supply on site | Do not assume a standard pump will work. Our standard QJ/QJT sets are three-phase, and a custom 220 V build does not automatically mean single phase. For single-phase sites, confirm the workable configuration with our engineers case by case, based on your model and supply conditions. |
| Three-phase available at the site | Choose three-phase for borehole duty. Better starting, better efficiency, lower cable cost. |
| Medium or large farm, irrigation project, water supply scheme | Three-phase without discussion. Our range covers 3–250 kW, 5–600 m³/h, heads 6–600 m. |
| Site runs on a diesel generator, no grid | Three-phase pump matched to the generator — see the generator note below. |
| Grid is 60 Hz, or voltage is 220 V or 660 V | Custom-built motor from the factory — see below. |
A note on generators. A motor’s locked-rotor (starting) current can reach about 6–7 times its rated current — this figure comes from our manual’s motor data. The generator capacity must cover this starting demand, not just the running load. The starting method — direct-on-line, reduced-voltage, soft-start, or variable-frequency — should be chosen for the specific motor, generator, and pipeline conditions together. Tell us the generator capacity when you ask for a quote, and our engineers will match the starting arrangement.
A note on 415 V. Some three-phase networks run at 415 V. Our manual’s custom-voltage list (60 Hz, 220 V, 660 V) does not include 415 V, so do not assume a standard 380 V motor can run on 415 V long-term. If your supply is 415 V, please confirm with our engineers before ordering — we will check the applicable motor and quote accordingly.
Custom Voltage and Frequency from the Factory
Standard production is 380 V, 50 Hz, three-phase. For markets with different power systems, the factory can build custom motors:
- 60 Hz versions for 60 Hz countries
- 220 V versions
- 660 V versions (used in some industrial and mining systems)
Two clarifications to avoid common misunderstandings. First, “220 V custom” refers to the voltage; it does not by itself mean a single-phase motor — phase must be specified and confirmed separately. Second, custom builds are quoted case by case: model, price, and lead time are confirmed with the factory per order. When you send an inquiry, always state your real supply: voltage, frequency, and whether it is single or three phase. One line like “380 V 50 Hz three-phase” or “60 Hz grid” saves days of email.
Protecting the Pump from a Difficult Supply
Whatever phase you use, protection decides how long the motor survives:
- Use a proper control panel — always. Every borehole pump set must have a control cabinet with short-circuit, phase-loss, and overload protection. Phase-loss protection matters especially where supply quality is poor: when one phase of three drops out, the panel trips before the winding burns.
- Measure your real voltage first. A multimeter reading at peak hours tells you more than the utility’s brochure. If voltage regularly sits outside ±5% of the motor rating, tell us — the answer may be a different motor, a stabilizer, or a transformer tap adjustment.
- Match the starting method to the supply. Where supply capacity is limited, reduced-voltage starting, soft starters, or variable-frequency drives cut the starting current and the mechanical shock on the pump. The choice depends on the motor, the supply, and the pipeline — our engineers can advise.
- Use the right cable. Undersized cable over a long run drops voltage before it even reaches the motor. Our selection tables give a matched copper cable section per model, from 2.5 mm² up to 95 mm², with double cables for large motors.
- Size the pump to the duty point. An oversized pump working against a throttled valve wastes power and runs hot. Our guides what size borehole pump do I need and well depth vs pump head (TDH) walk through the calculation, and how to choose a borehole pump covers the full checklist.
A Quick Checklist Before You Order
Run through these five questions at your site, and write the answers down:
- What does the meter actually say — voltage between phases, and between phase and neutral, at peak hours?
- Is the supply single phase or three phase — and does it stay within ±5% of nominal?
- Is the frequency 50 Hz or 60 Hz?
- If there is no grid, what is the generator’s rated capacity, and can it cover the motor’s starting current (about 6–7 times rated current)?
- How far is the pump from the power source? Long runs may need a larger cable section to keep voltage drop small.
Bring these answers to any supplier — us or anyone else — and the conversation becomes fast and factual. A supplier who never asks about your supply is guessing with your money.
Tell Us Your Supply, We Do the Rest
Send us four things: your voltage and frequency, single or three phase, the flow and head you need, and your borehole diameter. Our engineers will confirm whether a standard three-phase motor fits, quote a custom 60 Hz / 220 V / 660 V build where applicable, and — for single-phase sites or 415 V supplies — confirm what is possible before you commit to anything. You can also start with the pump selector or browse the borehole pump range.