Electrical Contract Works · Question

What is the difference between single-phase and three-phase supply for a workshop?

Short answer

Single-phase supply uses one alternating current line and suits lighting, fans, small appliances and light machines. Three-phase supply uses three lines working together and suits motors, compressors and heavier machinery, because it delivers power more smoothly and carries larger demand with lighter cabling. Most workshops with machines need three-phase, though the right choice depends on the equipment list.

In more detail

The difference is easiest to see through the equipment you plan to run. Household-style loads such as tube lights, computers and a small drill work happily on single-phase. Larger motors, welding sets, lathes and compressors are usually built to run on three-phase, and many will not run properly, or will run poorly, on a single-phase line.

Where each supply type usually fits
Aspect	Single-phase or three-phase
Typical loads	Single-phase for lights, sockets and small tools; three-phase for motors and heavy machines
Motor behaviour	Three-phase motors start and run more smoothly
Cabling	Three-phase carries more demand through lighter conductors
Supply request	Three-phase connection involves more equipment and different terms from the supply authority

A workshop often needs both. The designer usually runs three-phase to the machine area and splits it into single-phase circuits for lighting and sockets, keeping the demand shared across the three lines rather than piled on one.

Questions to settle before applying:

Which machines are rated for three-phase, according to their nameplates or supplier data.
Whether any machine has a heavy starting demand that the supply must tolerate.
How much equipment you may add in the next few years.

The supply authority decides what it will connect and on what terms, so ask for its current requirements before ordering machines. A qualified electrical designer should confirm the arrangement, since balancing load across the lines is part of safe and efficient design.

Key points

Single-phase suits lighting and small tools; three-phase suits motors and heavier machinery.
Check each machine's nameplate or supplier data to see which supply it expects.
Many workshops use three-phase for machines and single-phase circuits for lighting and sockets.
The supply authority sets the terms and process for each connection type.
Plan for future machines so you do not outgrow the connection quickly.

Who this applies to

Small manufacturers and fabrication workshop owners choosing a connection.
Promoters moving to new premises with different machinery.
Owners ordering machines before the electrical design is finished.

Last reviewed 3 October 2026

This answer is general information, not advice on your particular case. Terms, eligibility, and requirements change, so check the current position with the relevant institution or authority.