6-Wire Fan Motor Wiring Diagram

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Understand the 6-wire fan motor connection scheme for multi-speed single-phase and three-phase induction fan motors, including tapped winding and dual-voltage configurations.

A 6-wire fan motor is an induction motor with multiple external lead connections that allow different winding configurations for speed selection, dual-voltage operation, or starting characteristics. The specific function of each wire depends entirely on the motor design — there is no universal 6-wire colour code or connection standard, and misconnecting a 6-wire motor can cause it to overheat, run in the wrong direction, or fail to start.

In single-phase HVAC and ventilation fan motors, the six wires typically represent a combination of main winding taps (for multi-speed operation), a run capacitor connection terminal, and possibly a separate start winding lead. A common configuration has three speed leads (high, medium, low), a common return, a run capacitor terminal, and a neutral — giving six connections in total. Speed is selected by connecting the supply line to whichever speed tap is required; the capacitor remains connected in series with the auxiliary (start) winding for all speed settings.

In three-phase motors, a six-lead configuration typically represents a dual-voltage motor wound for either series (high voltage, e.g., 415V) or parallel (low voltage, e.g., 240V) winding connection. The six leads are designated T1 through T6 (NEMA convention) or U1, U2, V1, V2, W1, W2 (IEC convention). For high-voltage (series) connection, T1-T6, T2-T4, T3-T5 are joined (pairs in series) and three supply phases connect to T1, T2, T3. For low-voltage (parallel) connection, T4-T7 (non-existent in 6-lead motors — this applies to 9-lead motors), so in a 6-lead dual-voltage motor, the appropriate connections differ — see the motor nameplate diagram.

Some manufacturers use a different 6-wire arrangement for EC (electronically commutated) brushless motors, where the wires carry power supply, earth, and control signals (such as PWM speed control input, tachometer output, or alarm signal). These are not traditional AC induction motors and must be connected strictly per the manufacturer's datasheet.

The motor nameplate and wiring connection diagram (typically printed on a label inside the terminal box cover) is the authoritative source for any 6-wire motor connection. Never connect a 6-wire motor based on assumed colour coding.

How to wire 6 wire fan motor wiring diagram

Locate and read the motor nameplate and wiring diagram Before touching any wires, find the motor's nameplate (attached to the motor body) and the wiring connection diagram (usually on a label inside the terminal box cover or in the motor documentation). Record the voltage rating, current draw, capacitor specification (for single-phase motors), and the terminal designation for each lead. If the label is absent, obtain the model number from the nameplate and download the datasheet from the manufacturer.
Isolate power and verify dead Isolate the motor's supply at the distribution board or local isolator. Verify dead at the motor terminal box with a calibrated voltage tester before opening the terminal box. If the motor is part of a system with capacitors (single-phase motors), wait 2–3 minutes after isolation to allow capacitor discharge.
Identify winding groups using a multimeter (if no diagram available) If the connection diagram is missing, use the continuity function of a multimeter to identify which leads are electrically connected to which others — this reveals the winding groups. Leads within the same winding group will show continuity; leads from different groups will not. For a three-phase motor, expect three isolated groups of two leads each (one for each phase winding half).
Set terminal block connections for the required voltage (three-phase dual-voltage motors) For high-voltage (series) connection, link T1-T6, T2-T4, T3-T5 using jumper links in the terminal box, and connect supply phases L1, L2, L3 to T1, T2, T3 respectively. For low-voltage (parallel) connection, link T1-T4, T2-T5, T3-T6, and connect L1, L2, L3 to the pairs. Use the motor's connection diagram — not this general guidance — as the authoritative reference.
Connect the speed selection lead (single-phase multi-speed motors) Connect the supply line to the speed lead corresponding to the required speed (high, medium, or low as labelled on the motor). Connect the neutral to the common/neutral terminal. Connect the run capacitor between its designated terminal and the capacitor return terminal. Ensure the capacitor value and voltage rating matches the motor specification exactly.
Connect earth to motor frame Connect the protective earth conductor to the motor frame earth terminal (marked with the earth symbol or PE). In a metal terminal box, the box itself must also be bonded to earth. Earth continuity from the supply earth bar to the motor frame is mandatory — do not omit or defer this connection.
Perform a brief test run and measure current Restore power and measure the motor's running current on each phase (three-phase) or on the line conductor (single-phase) using a clamp ammeter. Compare the measured current to the nameplate full-load ampere (FLA) rating. Current significantly above FLA indicates a wiring error, mechanical fault, or overloaded fan. Shut down immediately if overheating or abnormal noise is detected.

Specifications

Motor type	Single-phase capacitor-run (multi-speed) or three-phase induction (dual-voltage), depending on design
IEC lead designation (three-phase)	U1, U2 (Phase 1 winding halves); V1, V2 (Phase 2); W1, W2 (Phase 3)
NEMA lead designation (three-phase)	T1–T6 (T1, T2, T3 = winding starts; T4, T5, T6 = winding ends)
High-voltage series connection (three-phase)	Link T1-T6, T2-T4, T3-T5; supply L1→T1, L2→T2, L3→T3
Low-voltage parallel connection (three-phase)	Link T1-T4, T2-T5, T3-T6; supply L1→T1/T4, L2→T2/T5, L3→T3/T6
Run capacitor (single-phase, typical range)	2 µF to 20 µF at 250V or 450V AC — must match motor nameplate
Protection class (typical HVAC fan motor)	IP55 (dust-protected and jet-water resistant)

Safety warnings

Never connect or energise a motor without confirming the supply voltage matches the motor nameplate voltage and the terminal connections are set correctly for that voltage. Connecting a dual-voltage motor to the wrong voltage with the wrong terminal configuration will cause immediate winding burnout and may cause fire.
Isolate and verify dead before opening a motor terminal box. In three-phase systems, all three phases must be proven dead. Single-phase motors with run capacitors retain potentially dangerous charge in the capacitor after supply isolation — wait 2–3 minutes and use a voltmeter to verify capacitor discharge before touching terminals.
Motor work on three-phase systems and on fixed wiring must be carried out by a licensed electrician in compliance with NEC (NFPA 70), BS 7671, AS/NZS 3000, or IEC 60364. Incorrect motor wiring can cause fire, equipment damage, and injury.
The motor frame must be earthed. A high-impedance earth or absent earth on a motor with a winding fault will energise the motor frame to mains potential — contact is potentially fatal. Test earth continuity from the supply earth to the motor frame before energising.
This diagram is an illustrative reference only. The motor's own nameplate connection diagram is the authoritative source for all terminal connections. Do not connect any 6-wire motor based solely on general guidance without verifying against the specific motor's documentation.

Tools needed

Calibrated multimeter with AC voltage, continuity, and resistance functions
Clamp ammeter (to measure running current against nameplate FLA)
Capacitance meter (to verify run capacitor value for single-phase motors)
Insulated screwdrivers and terminal drivers
Torque-limiting screwdriver or wrench (for terminal tightening to specification)
Cable strippers and bootlace ferrule crimping tool
Non-contact voltage tester

Common mistakes

Connecting a dual-voltage motor with the wrong link configuration for the supply voltage: The most common and most damaging mistake. High-voltage winding connected to low-voltage supply causes severely reduced torque; low-voltage winding connected to high-voltage supply causes immediate burnout. Always verify supply voltage and set links before energising.
Using the wrong capacitor value on a single-phase motor: A capacitor with too low a capacitance causes the motor to run slowly and draw high current. Too high a capacitance causes overheating and can burn out the auxiliary winding. Match capacitor µF and voltage rating exactly to the motor nameplate.
Omitting the overload relay on three-phase fan motors: Without overload protection, a motor that is stalled (blocked fan blade) or overloaded (belt driven against excessive static pressure) will burn out its windings. An overload relay is mandatory protection.
Connecting different winding groups in parallel by accident (confusing lead identification): In a three-phase dual-voltage motor, accidentally shorting leads from different winding groups causes a short-circuit condition — the motor will draw very high current and trip the supply protection immediately, potentially damaging windings.
Ignoring motor rotation direction on installation: A fan that runs in the wrong direction may appear to work but moves far less air than designed. Rotation direction must be verified on first start by briefly energising and observing the impeller rotation — confirm against the direction arrow on the motor or fan body.

Troubleshooting

Motor draws excessive current and overheats on startup: Cause: Wrong voltage connection (parallel winding connected to high voltage), failed run capacitor, mechanical binding, or blocked fan impeller Fix: Isolate immediately. Check supply voltage against motor nameplate. Check terminal link configuration. Test the run capacitor with a capacitance meter. Check impeller for blockage or mechanical seizure. Do not restart until the cause is identified.
Single-phase fan motor hums but does not rotate: Cause: Open-circuit run capacitor — the motor has no auxiliary phase, so it cannot develop starting torque and only produces a humming single-phase field Fix: Isolate and discharge the capacitor safely. Test capacitance with a capacitance meter — an open or significantly low-capacitance reading confirms failure. Replace with a capacitor of identical µF and voltage rating.
Three-phase motor trips the overload relay within seconds of starting: Cause: Locked rotor or mechanically jammed impeller, wiring fault causing one phase to be open-circuit (single-phasing), or overload relay set below motor FLA Fix: Confirm impeller rotates freely by hand with power isolated. Measure current on all three phases during starting — an open phase causes two phases to carry significantly more current. Verify overload relay setting against motor FLA. Correct the mechanical or electrical fault before resetting.

Frequently asked questions

Why does a fan motor have 6 wires instead of 2 or 3?

Additional wires provide access to different points within the motor windings. In a single-phase multi-speed fan, extra wires connect to different turns in the main winding, allowing speed selection. In a dual-voltage three-phase motor, the extra wires expose the midpoints of each phase winding so the coils can be connected in series or parallel. More wires give the installer greater configuration flexibility.

How do I know which wire is which on a 6-wire fan motor?

The motor's nameplate or the wiring diagram label inside the terminal box cover identifies each lead. Three-phase motors follow NEMA (T1–T6) or IEC (U1, U2, V1, V2, W1, W2) conventions. Single-phase multi-speed motors typically have a manufacturer-specific colour code printed on the motor label. If the label is missing, the motor must be tested with a multimeter to identify winding groups before connection.

Can I run a 6-wire dual-voltage three-phase motor on the wrong voltage by accident?

Yes, and it is a common and damaging mistake. Connecting a motor rated for parallel (low-voltage) operation to high voltage, or vice versa, can cause immediate coil burnout. Always verify the supply voltage against the motor nameplate and set the terminal connections accordingly before energising. The nameplate will show both voltage ratings (e.g., 220–240V / 380–415V) and specify which connection applies to each.

What is the purpose of the run capacitor in a single-phase 6-wire fan motor?

Single-phase induction motors require a capacitor to create the phase shift needed to generate a rotating magnetic field — without it, the motor cannot develop starting torque. The run capacitor remains in circuit during operation (unlike a start capacitor, which is switched out). In multi-speed motors, the capacitor is typically connected between a dedicated capacitor terminal and the neutral, and remains constant across all speed settings.

Does the connection change if I reverse the motor rotation direction?

In three-phase motors, rotation direction is reversed by swapping any two of the three phase supply connections. In single-phase capacitor-run motors, rotation is reversed by swapping the capacitor from one auxiliary winding terminal to the other — but this is possible only if the motor is wired to allow it, and many fixed-direction fan motors are not designed for reversal. Never attempt direction reversal without confirming the motor design supports it.

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