Two motors of identical horsepower can behave very differently depending on the supply behind them. If your site offers a choice, here is what actually changes.
Single-phase: what homes and small sites get
Standard 230 V single-phase is universal and simple to wire, but the motor needs a capacitor to start turning, and capacitors are a wear item. Starting torque is modest, efficiency is lower, and above roughly 2.2 kW the current draw starts to strain a domestic supply. For small domestic pumps and light farm duty, it is the practical default because it is the supply that exists.
Three-phase: what workshops and serious sites get
A 400 V three-phase motor starts itself cleanly, runs more efficiently, draws lower current per phase and survives heavy duty better. The same power in a three-phase motor is smaller, cooler and longer-lived. The catch: many rural and residential sites simply do not have three-phase service, and paying the utility to bring it in is rarely justified by the pump alone.
The deciding questions
- What supply exists on site today? Extending three-phase is often the whole budget.
- How hard will it work? Intermittent domestic duty forgives single-phase; continuous duty argues for three-phase.
- How big is the load? Past about 2 kW, single-phase becomes the awkward choice electrically even where it is possible.
Choose the motor for the duty and the supply for the site. When in doubt, tell us the supply rating and the daily runtime, and the right answer usually becomes obvious.