How to Install a Time Switch for an Exhaust Fan
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Installing a Bathroom Exhaust Fan Control Switch or Occupancy Sensor: Selecting and Wiring a Auto On or Auto Off Exhaust Fan Switch. |
Wiring a Bathroom Exhaust Fan Time Switch or Occupancy Sensor
Electrical Question: I have a small bathroom with a ceiling fixture that includes a light, a heat lamp with circulating fan and an exhaust fan.
- These are individually controlled by toggle switches in a 3 gang box. The exhaust fan is a small squirrel cage type that plugs into an outlet in the box. No other info available on it but I suspect it’s rated at about 50 to 80 CFM.
- What I am wanting to do is hook up the exhaust fan to a recycling timer so it goes on and off for specified periods of time.
- Most of these types of timers that replace the wall switch don’t offer the number of cycles a day I would need. The few that I have found that meet my requirements are designed to plug into an outlet and then the device plugs into it.
- As you can see in the photo I have included, the exhaust fan plugs into a receptacle in the box (I have it unplugged in photo). I could make a plug in timer work if I can figure out how to install it in between the fan and the fan receptacle in the box. I can’t plug the time into the receptacle in the box since there’s not enough room in the box AND, as you can see, the plug-in for the fan is two prong, non polarized and the timer is a 3 prong plug.
- So, can I take a two prong, non polarized lamp plug, put in on a lamp cord wire so it can plug into the receptacle in the box, and install a 3 prong plug receptacle to the other end of the wire that would then receive the plug-in on timer. Then I would plug the two prong, non polarized plug from the fan into the timer receptacle. Since the circuit isn’t grounded to begin with, putting a grounded wired timer in between shouldn’t be a problem. Right?
- If there’s another whole better way to do this that doesn’t cost a lot or require a minor remodel, I am totally open to any suggestions you might have.
This electrical wiring question came from Steve, in Steamboat Springs, Colorado.
Dave’s Reply:
Thanks for your electric wiring question Steve.
Preparations for Wiring a Control Switch for a Bathroom Exhaust Fan
Application: Installing a Bathroom Exhaust Fan Time Switch Control.
Skill Level: Intermediate to Advanced. This electrical wiring project is best performed by a Licensed Electrical Contractor.
Tools Required: Basic Electricians Pouch Hand Tools and a Voltage Tester.
Estimated Time: Depends on personal level experience, ability to work with tools and the access to the wall switch for the exhaust fan and if a larger switch box will be required.
Precaution: The bathroom exhaust fan circuit should be identified, turned OFF and Tagged with a Note before working with the wiring and installing the fan speed switch.
Notice: Modifying existing wiring or installing additional bathroom electrical wiring should be done according to local and national electrical codes with a permit and be inspected.
Important:
The exact wiring of a bathroom exhaust fan switch will depend on the exact switch that is selected, the type of exhaust fan that is installed, and the electrical circuit wiring in the bathroom. Please consult the installation manual and owners manual which is provided from the manufacturer for the aforementioned equipment.
Example of a Combination Bathroom Exhaust Fan
Selecting an Auto On or Auto Off Exhaust Fan Switch
- Digital Time Switches
- There are a number of digital timer switches that are fully programmable that may work great for the application described in this question.
- Brands of digital time switches include Leviton, GE, Stanley, Intermatic, to name just a few.
- There are a number of digital timer switches that are fully programmable that may work great for the application described in this question.
- Search for Digital Light Timer and you will see the variety of switches that can be installed in the existing switch box where the new switch can take the place of the existing switch.
- The new timer switch should have the capability for manual operation as well so the fan may be turned as needed.
- Occupancy Sensor Switch
- An occupancy sensor is a motion controlled switch that senses movement or the lack of movement. These switches can be turned on manually and when motion is not detected the occupancy switch will turn off automatically after a predetermined or programed time period has been reached.
- Occupancy sensors meet most energy efficient requirements and are typically installed in new or remodeled bathrooms.
- Manual Time Switch
- A manual time switch is typically a mechanical spring wound switch which allows the on time to be set up to the limit of the time switch.
- Spring wound time switches are typically available with time intervals of 15, 30 or 60 minutes.
Installing a Bathroom Exhaust Fan Control Switch or Occupancy Sensor
The wiring of the bathroom exhaust fan switch will depend on the exact switch that is selected, however below is a description of the most common control switches and how they are wired.
- Two Wire Timer Switch
- Typical wiring for exhaust fan switches with two switch wires and a ground wire:
- Line In connection – Power from the Electrical Circuit.
- Line Out connection – Power out to the exhaust fan.
- Ground Wire connection – bonds to the circuit ground wire.
- Typical wiring for exhaust fan switches with two switch wires and a ground wire:
- Three Wire Timer Switch
- Typical wiring for exhaust fan switches with three wires and a ground wire:
- Line In connection – Power from the Electrical Circuit.
- Line Out connection – Power out to the exhaust fan.
- White wire connection – Neutral wire of the Electrical Circuit.
- Ground Wire connection – bonds to the circuit ground wire.
- Typical wiring for exhaust fan switches with three wires and a ground wire:
Example of a Digital Time Switch
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