A ceiling fan’s electrical box must be labeled (by under writers Laboratories) to carry the weight of the fixture.
If you place a light kit on you ceiling fan, you can install wall switches to control the fan and light independently.
HOW TO: Wire a Ceiling Fan/Light
Tools and Materials
- Ceiling fan/light
- 12 or 14/2G NM cable
- Cable ripper
- Multipurpose tool
- Wire connectors
- Knockout punch
- Hanger Bracket (for fans over 35 lbs.)
- Fan switch
- Insulated screwdrivers
- 12 or 14/3G NM cable
- Long-nose pliers
- Cable clamps (if boxes are metal)
- Approved ceiling fixture box
- Square light switch box
- Light switch
Install the Electrical Boxes.
Cut an opening in the wall for the light switch box and another in the ceiling for the fan/light box. Fish 12 or 14/2G NM cable from the breaker panel to the switch box opening and 12 or 114G MN cable from the switch box to the fan/light box opening in the ceiling. Install the switch box, and pull both cables into the box. Rip open 10 inches of each cable, and remove the excess sheathing. Secure the cables in the box, and strip the wires. Do the same for the cable in the fan/light box. The three wire cable from the switch box to the fan/light box allows you the option of controlling the light and fan independently. If you decide that you do not want to have independent control, run the three wire cable anyway so you will preserve the option for later.
Wire the Electrical Boxes.
Although there are two ways to run power to a ceiling fan/light through the ceiling box or through the switch box the preferred way is to bring power to the fan/light through the switch box. This makes trouble shooting easier and minimizes crowding wires in the ceiling box. Using wire connectors, in the fan/light ceiling box, splice together the black hot wire from the fixture and the hot black lead wire from the fan switch. Connect the hot red wire from the fan/light to the hot black lead wire from the light switch. Next, connect the white neutral wire from the switch box and the white neutral wire from the fixture. Then splice the green grounding wire form the fixture to the bare copper grounding wire from the switch box. In the switch box, pigtail the hot black feeder wire to both switches, and connect the white neutral feeder to the white neutral from the fixture. Then connect the hot wire s from the fixture to their respective switches. Push the switch wires into the box, screw the switches in place, and install the cover plate. Then install the mounting plate and ceiling fixture in accordance with the manufacturer’s directions.
End of Run ceiling Fan/Light Wiring
In this arrangement, a two wire cable feeds power into a start of run double ganged switch box. It then proceeds to the end of run combination ceiling fan/light along a three wire cable. The fan/light fixture is controlled by separate speed control and light dimmer switches.
Start of Run Ceiling Fan/Light Wiring
Following a switch loop configuration, in this layout power flows first to the fan/light fixture through two wire cable. It then proceeds to the double ganged end of run switch box and back to the fixture along a three wire cable.
Whole House fans
Installing a whole house fan in an attic floor is a great way to remove excess heat buildup in your home. The volume of air moved by a fan is measured in cubic feet per minute (CFM). The fan capacity you need is determined by the cubic volume of your home. The CFM rating of the fan also determines the amount of venting area you will need to prevent air pressure from building up in your attic space. As an alternative, a whole house fan can be installed in an attic gable, but you will still need a louver in the attic floor. It is better to put the entire unit in the floor and use the gable ends and eaves for ventilation. In either case, the size of the fan and venting area must be calculated on the basis of the volume of space being vented. The airflow drawn through screened windows and doors must be at lest equal to the airflow thorough the ventilation system.
A properly sized whole house fan is capable of changing the air in you home within one to three minutes.
How to: Install a Whole House Fan
Tools and Materials
- Whole house fan
- Stepladder
- Measuring tape
- Circular saw
- 2x joist lumber
- ½ in. rigid foam board
- Multipurpose tool
- 12/2G and 12/3G NM cable
- Speed control fan switch
- Wire connectors
- Safety glasses
- Screened louver vents
- Keyhole saw
- Pencil
- Carpenter’s hammer
- Bracing lumber
- Nails
- Insulated screwdrivers
- Long nose pliers
- Junction box
- Switch box
- Wire staples
- Work gloves
- Dust mask
Frame the Fan Opening.
Choose a suitable location for your whole house fan, and mark an outline for the cutout on the ceiling. A hallway or other central location is best. In a two story home, locate the fan where it will be able to draw air up from the first floor with minimal interference, for instance at the top of a stairway. Using a keyhole saw, cut away the drywall, and expose the framing joists in the ceiling. Brace the ceiling joists, and cut the opening for the fan frame. Using two by joist lumber to match the existing framing, install double headers and trimmer joists to frame the opening for the fan. Be sure to follow the manufacturer’s directions when measuring the rough opening required.
Build the fan Enclosure.
Install the fan in the rough opening following the fan manufacturer’s instructions. In the attic, build an insulated plywood box enclosure around the fan. Make the enclosure high enough to clear the fan housing, and include a cover for the box. Attach rigid insulation to the attic surfaces of the box and cover. Do not fasten the cover to the top of the box it will be used to seal the fan box when it is not in use during the winter months. From the hallway below, screw the metal louver in place on the ceiling side of the fan opening. Be sure the louver blades are not warped or bent and that they open and close freely.
Wire the fan.
Shut off the power at the main panel, and install a junction box outside the fan enclosure. Run 12/2G NM cable from the panel to the junction box, stapling it to the framing along the way. Pull the cable into the box and secure it. Rip and remove 10 inches of cable sheathing and strip the exposed wires. Using wire connectors, in the junction box, splice the black hot wire form the branch circuit cable to the white wire (coded black) from the switch. Connect the white neutral from the branch circuit cable to the white neutral from the fan. Splice the red wire from the fan to the red wire form the switch and the black wire from the switch to the black wire form the fan.
Wire the Switch Loop.
Using appropriately sized wire connectors in the switch box, splice the black hot wire from the switch leg to one of the black hot wires from the switch. Connect the switch leg white wire to the other black wire form the switch. Mark the white wire with black tape to indicate that it is hot. Connect the red wires. Next, splice the switch leg bare copper grounding wire to the grounding wire on the switch. If the box is metal, pigtail the grounding wires to the grounding screw terminal in the switch box. Tuck the wires in the switch box, and install the cover plate. Then on the breaker at the main panel, and test the circuit.
Calculating Fan/Vent Sizes
To determine fan size, first calculate the total volume of all the rooms in your house. Multiply the length x width x height of each room, and add them all together. An ideal airflow would be one air change per tow minutes. Simply divide the total room volume by 2 to obtain airflow in cubic feet per minute (CFM). A 2,000 sq. ft. home with an 8 ft. ceiling height, for example, would be 16,000 divided by 2 + 8,000 CFN. For such a house, you would need a fan having an airflow rate of 8,000 CFM. The venting area would be about 1 sq. ft. of unobstructed space per 750 CFM of airflow. In this example, that would be almost 11 sq. ft. For ¼ in. screen multiply this by a facto of 1.00; for 1/8 in. screen, 1.25; and for 1/16 in. screen, 2.00.
Fan sizes and exhaust ratings
Fan size Typical exhaust rating in CMF
24” 3,500-5,500
30” 4,500-8,500
36” 8,000-12,000
42” 10,000-15,000
48” 12,000-20,000
An effective fan will change the air in a house at least once a minute. Check the manufacturer’s exhaust rating in cubic feet per minute
(CFM) to determine whether a fan has the capacity you need.
Tips on Using Whole House Fans
The Home ventilation Institute recommends the following for getting the best use from a whole house fan.
- In the early evening when the outdoor the temperature begins to drop, open doors and windows and turn on the fan to cool the house.
- At bed time, close all but bedroom windows.
- In early morning, open all windows and allow fan to cool down the rest of the house.
As outdoor temperature rises, close all doors and windows to keep the cool air inside. It is also a god idea to close drapes on the sunny side of the house.