By Kevin Beck – Updated Aug 30, 2022

Three‑phase motors deliver superior efficiency compared to single‑phase units. By using three alternating currents that cycle through separate conductors, the power available is ×∓3.87—approximately 1.732 times higher than a single‑phase system of equal voltage. Electrical power remains the product of voltage and current flow.

When wiring a three‑phase motor, you’ll encounter either a Y (wye) or delta configuration. Motors can have six or nine leads, which determines whether you can choose between high‑ and low‑voltage wiring. A nine‑lead motor offers four distinct wiring options, while a six‑lead motor is limited to one configuration. Programmable logic controllers (PLCs) may also be integrated into the circuit.

Typical lead colour codes are: L1 = black, L2 = red, L3 = blue. Motor leads T1–T9 are, in order, blue, white, orange, yellow, black, gray, pink, red, brick red. Always refer to a wiring diagram before proceeding.

Wye (Y) Configuration – Low Voltage

Connect the following pairs of motor leads to the line conductors:

• 1 & 7 → L1 (black)
• 2 & 8 → L2 (red)
• 3 & 9 → L3 (blue)

Join the remaining leads (4, 5, 6) together and connect them to the motor’s neutral point.

Wye (Y) Configuration – High Voltage

Make the following connections:

• 1 → L1, 2 → L2, 3 → L3
• 4 → 7, 5 → 8, 6 → 9

Delta Configuration – Low Voltage

Wire the motor leads as follows:

• 1, 6 & 7 → L1
• 2, 4 & 8 → L2
• 3, 5 & 9 → L3

Delta Configuration – High Voltage

Use these connections:

• 1 → L1, 2 → L2, 3 → L3
• 4 → 7, 5 → 8, 6 → 9

Before powering the motor, verify all connections, ensure proper insulation, and confirm that the motor’s voltage rating matches the supply. When using PLCs, program the logic to accommodate phase sequence and protection settings.

Follow these guidelines to wire your high‑ or low‑voltage three‑phase motor safely and efficiently.