Exhaust fan wiring diagram
Clear wiring diagram and step-by-step guide for wall-mounted speed fans — wiring to switch, speed regulator, capacitor and safety earth for reliable home or commercial installation.
fan control wiring
Wall-mounted speed fan wiring runs the live conductor to the motor via a wall switch or speed regulator and neutral returns directly, and earth is bonded to the fan housing. In capacitor-assist fans, the capacitor in series goes between motor terminals (or between regulator and motor) to give correct starting and speed control - follow the motor nameplate and follow the regulator wiring diagram to ensure that the correct terminals are interconnected and that operation is safe.
Formula & Table Summary:
Basic relations:V = supply voltage (e.g. 230 V)I = P / V (approx. motor running current), where P is motor rated power.
Capacitor current (AC):Ic = 2πf C Vph — useful when sizing run/start capacitors (f = supply frequency, C in Farads, Vph = phase voltage).
Wiring rule: Live → switch/regulator → motor (L); Neutral → motor (N); Earth → fan body (PE). Ensure regulator and capacitor ratings match motor & supply.
| Item | Connection | Typical Value / Note |
|---|---|---|
| Supply Voltage | L, N | 230 V AC (commonly) |
| Switch / Regulator | Series with Live | Triac/variator or multi-position switch |
| Motor Live (M-L) | From regulator output | To motor main winding |
| Motor Neutral (M-N) | Direct to supply N | Return conductor |
| Capacitor | Between motor terminals or via regulator | Rated for motor voltage and AC use (µF per motor spec) |
| Earth (PE) | Bond to fan body | Safety — mandatory |
fan speed regulator wiring
A wall mounted speed fan wiring diagram shows how to connect a fan to a supply, a switch, speed regulator (slider/rotary) and capacitor when it is required. Standard types of wall fans include single-phase motors that are either permanent split capacitor (PSC) or shaded-pole driven; a number of them incorporate a speed regulator (triac or autotransformer-type) or multi-tap capacitor to vary the motor speed. Wiring has an L to switch input/regulator output, fan motor live to regulator output, earth (PE) to front fan metal body and neutral (N) to motor neutral. Correct corr capacitor terminals will attach to motor and regulator, depending on manufacturer, when a capacitor is used (start/run). Correct fusing, secure connections, correctly sized cable all eliminate the possibility of overheating and long service life. Typical layouts are described in this guide, including single ON/OFF switch, several speed selector, regulator (variator) connections, capacitor-assisted motors and any safety advice and test procedures in commissioning.
fan earth connection
| Wiring Step | Input / Item | Expected Output / Result |
|---|---|---|
| 1 | Supply L→Switch | Switch controls live feed to fan |
| 2 | Switch→Regulator→Motor L | Speed varies with regulator setting |
| 3 | Supply N→Motor N | Completes motor circuit, fan runs |
| 4 | Capacitor connection | Improved starting torque / stable speeds |
| 5 | Earth → Fan body | Safety bonding; reduces shock risk |
Frequently Asked Questions - Exhaust fan wiring diagram:
What cables are typically used for wall fan wiring?
Use 1.0–1.5 mm² for lighting-style fans and 1.5–2.5 mm² for higher power fans, per local code.
Where does the regulator go in the circuit?
In series with the live conductor — supply L → regulator → motor live.
Do all wall fans need a capacitor?
No — only motors specified as PSC or those requiring start/run capacitors need them.
Can I connect a timer or remote?
Yes — timer/remote control modules typically switch the regulator or contactor in the live side.
How should I earth a metal fan body?
Connect a green/yellow earth conductor from the fan body earthing terminal to the building earth bus.
What safety checks after wiring?
Verify polarity, insulation, secure terminals, regulator operation, capacitor polarity (if DC electrolytic — rarely used in AC), and earth continuity.
Is a dedicated circuit required?
Small fans may share lighting circuits per code; high-power fans should be on dedicated circuits with proper protection.
How to test the capacitor?
Use a capacitance meter or swap with a known good capacitor rated for the motor voltage.
What regulator type is best for wall fans?
Use AC-rated triac/variator designed for motor loads or approved multi-tap autotransformer regulators.
Who should perform the installation?
A licensed electrician should install and certify permanent wiring per local electrical regulations.
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