How to Replace a Bathroom Exhaust Fan and Ductwork – Part 6

By |Last updated on |Bathroom, Heating & Air|4 Comments

Bathroom ventilation fan wiring, connect the flexible air duct and mount the fan in the drywall ceiling. This project is continued from How to Replace a Bathroom Exhaust Fan and Ductwork – Part 5.

How to Wire a Bathroom Ceiling Fan

Remember, the electricity was shutoff at the main circuit breaker panel to prevent electrical shock and/or death in the previous installment of this project.

I’ve temporarily suspended the Panasonic FV-11VQ5 bathroom vent fan from a general purpose steel wire wrapped around a pan head screw set high on the joist where it’ll be clear of the fan body so I can work with two hands to connect the electrical wiring and ductwork while on the step ladder.

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Suspension Wire

To connect the Panasonic FV-11VQ5 vent fan wiring:

  1. Remove either the top or side knock-out from the fan junction box with a flat head screw driver.
    I removed the top knock-out because this will be the most direct path for the house wiring.
  2. Remove the fan junction box screw and cover.
  3. Lift the spring tab on the Raco 1/2″ REDI-LOC Connector.
  4. Slip the NM-B 14/2 wires through the REDI-LOC connector.
  5. Twist/press REDI-LOC connector over the end of the aluminum flex cable.
  6. While holding the REDI-LOC connector on the flex cable, insert the wires into the fan junction through the knock-out hole.
  7. Hook the stationary metal tab of the REDI-LOC inside the fan junction box, then squeeze the REDI-LOC spring tab closed and push the tab into the fan junction box to secure it to the box.

A minute or two of study and practice to see how the REDI-LOC connector works and you’ll have it down.

Bathroom Ventilation Fan Electrical Wiring

Bathroom Ventilation Fan Electrical Wiring

Take a 2 inch piece of duct tape and reach into the ceiling and feel along the aluminum flex cable to the other end. The red plastic Milne No. 0 MM Bushing that was installed in Part 5 has most likely slipped out of the flex cable. Push the red MM bushing back into the flex cable so the sharp edges don’t chaff the NM-B 14/2 cable and secure it with that short piece of duct tape so it doesn’t slip out again.

The fan wires are pre-stripped stranded copper wire. Should your fan wires be broken or badly frayed, cut off the expose wire and strip 5/8 inch insulation from the end of the wire. Twist the ends of the stranded copper fan wires in a clock-wise direction to make a tight lead.

For each fan wire, hold the wire even with the same color NM-B 14/2 house wire and use wire nuts (not supplied with the fan) to connect the:

  • Green fan wire to the bare copper ground wire.
  • White fan wire to the white (neutral) house wire.
  • Black fan wire to the black (hot) house wire.

Here’s a closeup of the Panasonic vent fan wiring connections and REDI-LOC flex conduit connector:

Bathroom Ventilation Fan Electrical Wiring Connections

Bathroom Ventilation Fan Electrical Wiring Connections

Tuck in the fan wires then snap on the metal junction box cover and secure it the cover screw:

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Junction Box Cover

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Junction Box Cover

Bathroom Vent Fan: Flexible Duct Connection

To attach the exhaust fan duct:

  1. Slip a 4 inch metal worm gear band clamp over the flexible vent duct.
  2. Slip the 4 inch flexible duct over the fan duct adapter.
  3. Wrap two layers metal foil HVAC tape over the vent duct to seal it to the fan duct adapter.
    Do not use standard “duct tape” because it will not hold.
  4. Slide the worm gear clamp over the duct and duct adapter, then tighten the clamp with a screw driver until it’s firmly snug.

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Vent Duct Attachment

Panasonic WhisperCeiling Ceiling Mount

Remove the temporary suspension wire from the fan and remove the wood screw that was set in the ceiling joist, then slide the fan into the drywall ceiling mounting hole. I mounted the fan to the ceiling joist and 2×2 wood frame with four of the Simpson Strong-Tie SD8 #8 1-1/2 inch pan head wood screws as shown:

Panasonic WhisperCeiling FV-11VQ5 Vent Fan: Drywall Ceiling Installation

Panasonic WhisperCeiling FV-11VQ5 Vent Fan: Drywall Ceiling Installation

Notice how the metal flange is fastened against the drywall ceiling in an “old work” installation between the bathroom ceiling and 2nd floor that is not covered in the Panasonic WhisperCeiling installation instructions.

Bathroom Vent Fan: Interior Soffit Flexible Duct

The Panasonic WhisperCeiling exhaust fan basic installation is now complete and I’m eager to see how well it works with the flexible duct and that “pinch point” through the garage ceiling to the interior soffit.

The flexible vent duct from the bathroom will be connected a second section of insulated flex duct (not shown) to the outdoors with a 4 inch galvanized pipe connector:

Bathroom Vent Fan Duct Installation: Interior Soffit and Duct Connector

Bathroom Vent Fan Duct Installation: Interior Soffit and Duct Connector

The flexible duct is slipped over the duct connector to the center rib:

Bathroom Vent Fan Flex Duct Installation: 4 inch Duct Connector

Bathroom Vent Fan Flex Duct Installation: 4 inch Duct Connector

And sealed with two layers of HVAC metal foil tape:

Bathroom Vent Fan Flex Duct: Duct Connector Sealed with HVAC Tape

Bathroom Vent Fan Flex Duct: Duct Connector Sealed with HVAC Tape

Panasonic WhisperCeiling Fan Testing

The Panasonic WhisperCeiling FV-11VQ5 exhaust fan is installed in the bathroom ceiling and ready for testing. My main concern is if the air flow will be significantly reduced by that rectangular hole (pinch point) in the garage ceiling. Elbows, kinks and long duct runs of vent duct create friction and impede the airflow.

I turned on the electricity at the circuit breaker panel and switched on the fan inside the master bathroom. Wow! The fan was really quite! Especially compared to the old and very noisy bathroom fan.

Back in the garage I could feel a strong air flow blowing from flexible duct. This video of a strip of newspaper flapping demonstrates the fan is working quite well:

This project is continued in How to Replace a Bathroom Exhaust Fan and Ductwork – Part 7.

Hope this helps,

Bob Jackson

Copyright © 2019   Reproduction strictly prohibited.


  1. John Beecroft January 27, 2013 at 1:38 pm - Reply

    I have a suggestion. Some of the repairs and connections shown use wire nuts. SInce this website shows worldwide You may like to state that these repairs are for use in the USA and Canada only! In other countries, the use of wire nuts is a violation of electrical codes, Some alternatives include insulated screw blocks (terminal strips) which meet most UK and European codes.

    Thanks for the website and the great ‘how tos’


    • BobJackson January 27, 2013 at 5:24 pm - Reply

      Thanks for the pointer. I trust that readers will adhere to the regulations for their region.

  2. Ross August 30, 2016 at 3:53 am - Reply

    I realize this is an old article, but someone may still refer to it for their project:

    I am sure this will help many people install their own vent fans. I do wonder why you suggest using the metal flex conduit to sheath the romex? I only see this as adding unnecessary material, cost and time to a project. Is this required in your jurisdiction? I have decades of experience in California and Washington, nowhere else though.

    My suggestions would be to omit the metal conduit, and use either a metal 1/2″ romex connector (2 screw) or a plastic romex connector (snap in) to connect the romex directly to the junction box. Easier, code compliant and safe.

    A bigger issue that might be encountered though:

    Older exhaust fans often had the electrical junction box and ducting located on opposing sides of the fan housing. Panasonic fans are still the best product you can buy, however the junction box and duct are located on the same side. If the existing wire is not long enough to make it to the new location, you will have a problem. I would suggest looking for an alternative that more closely matches the unit removed. Best of luck!

    • Bob Jackson August 31, 2016 at 1:03 pm - Reply

      I used metal flex conduit per the fan manufacturer’s installation instructions. The Panasonic and Broan bath fans I’ve installed both called for metal flex conduit. To my knowledge it’s not an NEC requirement. Maybe the fan manufacturer is concerned about possible vibration and rubbing?

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