How to Wire Humidity Sensor and Fan Control Switch

Electrical Technology

Wiring a Humidity Sensor and Fan Controller Switch

Table of Contents

Humidity Sensor & Fan Controller

A humidity sensor and fan control switch is a single-pole automatic control device designed to operate a ventilation or exhaust fan in response to changing humidity levels. It is commonly used in bathrooms, laundry rooms, basements, spas, and other areas where excess moisture can accumulate and cause condensation, mold, and mildew growth.

The humidity sensor continuously monitors the relative humidity level in the room using advanced digital sensing technology and an onboard microprocessor. When the humidity rises above the selected set point due to activities such as showering, bathing, or washing, the switch automatically activates the connected ventilation fan to remove excess moisture from the air. Once the humidity level returns to normal, the fan continues to operate for the selected delay period before automatically turning off.

The device features adjustable humidity sensitivity and programmable fan run-time settings. This way, it can be configured for customize operation according to room conditions and ventilation requirements. Despite the automatic operation, the switch can by manually ON/OFF to control the exhaust / ventilation fan.

The humidity sensor and fan control switch can be installed in new construction projects or used as a direct replacement for an existing single-pole switch. Depending on the wiring configuration, the device can operate with or without a neutral conductor. The automatic operation reduces the energy consumption and reduce the electric bill.

The device supports compliance with modern residential ventilation requirements and green-building standards, including ASHRAE Standard 62.2, California Title 24 (Part 6), and the 2019/2022 CALGreen Standards where applicable.

Rating & Features

Name: Humidity Sensor and Fan Control Switch – Decora DHS05 & IPHS5
Poles: Single-Pole
Voltage: 120V 1-Phase AC Supply – 60 Hz
Fan Load: Motor Fan: ¼ HP, LED/CFL: 300W, Incandescent/Halogen: 600W or ELV/MLV: 400VA
Time Delay: 10, 20, 30, and 45 Mins.
Wire Size: #14 – #12AWG Copper
Neutral Wire: Preferred, but not needed
Termination: Wired Leads / (Side Wired – Screw Termination and Mounting for Older Model “IPHS5”)

Wiring a Humidity Sensor and Fan Controller Switch

Leviton has two models for humidity sensor with fan controller switch. The older version IPHS5 (discontinued) is replaced with DHS05. The newer version (DHD05) is a combination of humidity sensor and fan control with light switch.

Let see how to wire and install the newer version or replaced the existing old model in a 120/240V panel as the wiring method is almost same for both devices.

Before installing a new switch or replacing an existing single-pole switch, make sure the power is completely disconnected at the circuit breaker or fuse.

As shown in the wiring diagram, the humidity sensor with 4 built-in wires is connected to the branch-circuit conductors as follows:

The hot (black) wire from the circuit breaker is connected to the LINE terminal.
The neutral (white) wire from the panel is connected to the N (Neutral) terminal of the switch and then continued to the load.
The equipment grounding conductor (bare copper or green wire) from the panel is connected to the G (Ground) terminal as well as load.
The fan is connected to the FAN LOAD terminal through the switch’s built-in black wire.

The DHS05 switch requires a neutral connection for proper operation. If a neutral conductor is not available in the switch box, connect the equipment grounding conductor (EGC) to the neutral terminal (white wire) as permitted by the manufacturer’s instructions. If a neutral conductor is present, remove the green sleeve from the white wire and connect it to the branch-circuit neutral conductor.

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Since the DHS05 and IPHS5 humidity sensor switches are designed to control only the fan load, you may consider using the newer DHD05 model (combination humidity sensor, fan control, and light switch) to control both the fan and lighting loads separately using a single device.

If the fan and light are supplied by the same hot (line) conductor, both loads can be operated together through the fan-control portion of the switch. In this configuration, whenever the humidity sensor activates the fan, the light will also turn on.

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Good to Know:

The DHS05 models has pre-stripped wired leads. In case of IPHS5 (for side wiring), the suitable torque range is 14 -18 in.-lbs. for termination.
Install the humidity sensor in a location where it can readily detect steam generated within the bathroom.
Do not install the sensor directly above a heater or near HVAC supply registers, ventilation openings, doors, windows, or other areas exposed to air drafts, as these conditions may affect sensing accuracy.
It is not recommended to use this device to control a fan/light combination unit when the light fixture is the room’s only source of illumination, as the light may turn off automatically when the fan cycle ends.
In enclosed or confined spaces, the humidity sensor and fan controller may not perform effectively unless a properly sized ventilation or exhaust fan is installed and capable of removing excess moisture from the area.

Testing & Setting

Restore power to the switch and allow 10-20 seconds for the sensor to initialize properly. During this startup period, the green indicator light will blink approximately every 5 seconds.

Press the push button to test the connected load (exhaust fan). If the fan operates correctly, install the wall plate to complete the installation.

The built-in timer can be configured for 10, 20, 30, or 45 minutes. By default, the device is set to a 20-minute run time with Auto-ON High Sensitivity enabled and the humidistat adjusted to 50% Relative Humidity (RH). In this configuration, the exhaust fan operates in Automatic ON/OFF mode.

To configure the operating mode and other settings (Test Mode, Bath Fan Mode, Air Cycle Mode, and Humidistat Mode), refer to the user manual and follow the step-by-step programming instructions for DHS05. For setting the older version switch (IPHS5, refer to this user manual guide).

In addition to automatic operation, the exhaust fan can be turned on manually at any time by pressing the fan button on the front of the switch.

Instructions & Precautions.

Always disconnect the power supply by switching OFF the circuit breaker at the main service panel before installing, removing, or servicing the device.
Do not use aluminum conductors with this device. Use only copper or copper-clad conductors.
Do not install the switch directly above a heat source or in locations where hot or cold air drafts can blow directly onto the sensor. Such conditions may interfere with the sensor’s operation and can result in inaccurate humidity detection or reduced performance.
Humidity-sensing switches are intended for indoor use only.
If you are unfamiliar with electrical wiring procedures or are unsure about any part of the installation, consult a qualified electrician. All installations must comply with applicable local electrical codes and regulations.

Disclaimer:

The author will not be liable for any losses, injuries, or damages from the display or use of this information or if you try any circuit in wrong format. So please! Be careful because it’s all about electricity and electricity is too dangerous. If you are unsure, contact a licensed electrician to do it according to the local area codes.

Resources:

Smart Devices Wiring Series

Wiring Standard GFCI & Breakers

Wiring General Outlets & GFCI/AFCI Receptacles

Switches Wiring

Sizing Breakers, Wires & Panels

Finding the Number of Breakers/Outlets in a Circuit