Electrical Wiring for a Bath Light Fan Combo
How do I wire the switches for my bath fan and light? How to Identify Electrical Wiring for Installing a Bath Fan Combo with a Light, Wiring Connections for a Bathroom Exhaust Fan.
Wiring a Bath Fan Combo
Electrical Question: How do I wire the switches for my bath fan and light?
I have a junction box in an old house that was used to power a bathroom light.
- I have a junction box in an old house that was used to power a bathroom light.
- I would like to swap the light for a light/fan combo.
- The junction box of the original light has two Romex cables coming into each side.
- The wiring is very weird. Three of the Romex black wires are connected in a wire nut, the forth goes to the light. The four whites are wired together and go to the light. The grounds are also wired together.
- I copied this to the rest of the circuit and it works fine, but the fan and light doesn’t work.
This electrical question came from: John, a Homeowner from Denver, CO.
Thanks for your electrical question John.
How to Wire a Bath Fan Combo with a Light
Application: Wiring a Bathroom Exhaust Fan
Skill Level: Beginner to Intermediate, best installed by a licensed electrical contractor.
Tools Required: Basic Electricians Pouch Hand Tools, sheet rock saw, stud locating sensor, a non-conductive ladder, drop cloth and a Voltage Tester.
Estimated Time: Depends on personal level experience, ability to work with tools and the access to the attic area above the bathroom for the new exhaust fan.
Precaution: If there is an existing circuit then it should be identified, turned OFF and Tagged with a Note before working with the wiring.
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.
Wiring Connections for a Bathroom Exhaust Fan
How to Identify Electrical Wiring when Installing a Bath Fan Combo with a Light.
- When installing a bathroom fan unit it is best to use a voltage tester to identify the wiring.
- What you are describing tells me that:
- You may have wired into a switched leg that leads down to the wall switch and returns back to the ceiling junction box location.
- A Switched leg wiring configuration does not have a neutral wire, but actually uses the white wire to switch the power leg only.
- This can be fixed by making the proper connections at the junction box with the new cable for the combo exhaust fan.
- At the junction box, locate the neutral wires and connect to that group the new neutral wire, and then locate the the switched leg that returns from the wall switch for the power and connect the black wire for the power, then connect this cable to the bath combo exhaust fan.
- What you are describing tells me that:
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