DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Electrical (
-   -   Need help installing a combo fan/light over shower (

mbaughan 02-19-2010 09:18 AM

Need help installing a combo fan/light over shower

I'm new here, but a lifelong DIY guy, for better or worse :wink:
I have a done a few simple electrical installations but electrical is one of my "blind spots" please assume total ignorance if/when directing a response (and any responses are greatly appreciated!).

I currently have a light directly above a shower in a bathroom of a circa 1985 house. The bathroom has no fan and so towels, shower curtains, etc. get moldy fast. I want to install a fan with the least amount of hassle and $$.

I purchased a combination light/fan from HD that I'd like to swap out with the existing light. Existing light shares a switch with the light above the sink and is the only switch in the room. Room also has two double outlet receptacles on either side of a his and hers double sink, one of which is GFIC. Both lights and both outlets are fed by the same 15a breaker.

I'd like to simply add a second switch next to the existing one, and use one switch to control the light over the sink and the other switch to control the light/fan combo.

All of that I think I can handle. What I need help with is the fact that apparently this light/fan combo needs to be installed on a "GFIC branch circuit." Does the presence of a GFIC outlet on the same circuit qualify, or must I install a GFIC breaker at my box?

Secondly, the placement in question is directly beneath my attic and about four feet from a soffit. I do not want any additional holes in my walls or roof (having trouble keeping the house warm as it is). How misguided would it be to simply duct the exhaust from the fan to a soffit vent? Can I use dryer ducting for this, or must it be something special. Insulating the duct would be smart, right, to reduce condensation?

Thank you kindly for any advice offered.

Jim Port 02-19-2010 09:28 AM

The fan unit itself will need to be GFI protected. Just having a GFI in the circuit somewhere else will not meet code. There are GFI switches available to help provide this protection.

The mechanical code requires the venting to be to the exterior, not just above a vented soffit.

daveb1 02-19-2010 09:30 AM

Depending on your location soffit venting is an opton but not always a good one, as the moist air can drift back into the soffit vent and moisturize your attic.From your electrical description it sounds to me like you will need a new cable to your new fixture for it to be on it's own switch.And again depending on your location and if your bathroom is cabled to the GFCI outlet first then the rest of the bathroom might be protected as well.

secutanudu 02-19-2010 09:30 AM

A GFCI outlet protects anything connected to its "LOAD" side terminals. It does not matterif you use a breaker or outlet, as long as the fan/light will be fed off the load side of the outlet, not the line side. Press the test button on the GFCI. If the device in question stops working, you know it was protected by the GFCI. Everything in your bathroom other than your over-sink light needs to be GFCI protected.

New code requires 20A outlets in bathrooms, and if this circuit powers both lights and outlets in a bathroom (like yours), it can power NO other room, including other bathrooms. I do not know if you are required to retrofit all of this since you are only adding a fan, not remodeling the bathroom.

Does the fan you bought say it is rated for use inside a shower?

I would not vent to a soffit. Others here may disagree, but there is a chance of that moist air making its way back into your attic. I'd go through the gable side of the house if possible. Make sure the vent is pitched towards the outside. You can buy insulated duct for this, and have as few turns as possible.

How many wires are in your switch box? If you only see two (black and white) it is a switch loop and you'd need to run wires. If you see 4, you have hot power in the switch box and this is better.

secutanudu 02-19-2010 09:31 AM


Originally Posted by Jim Port (Post 402526)
The fan unit itself will need to be GFI protected. Just having a GFI in the circuit somewhere else will not meet code. There are GFI switches available to help provide this protection.

Really? Why is this? I believe you, just curious why a single GFCI protecting a whole bathroom is not adequate.

daveb1 02-19-2010 09:31 AM

Go with Jim's advice he types faster and knows more code than me.

mbaughan 02-19-2010 09:40 AM

Wow, you guys are fast. Thanks much for the replies.

Pushing the test button on the GFI receptacle only disabled the receptacles in the room, not the lights, so even though they share the same breaker I guess they are on a different circuit :huh:

Jim, so rather than installing a GFI breaker, I can install a GFI switch?

Bad news re: external venting requirements. Guess this won't be as cheap or as easy as I hoped (but what is, right?).

Re: rating of the light/fan, here's the language on the box: "UL listed for use over tub or shower when installed in a GFCI protected branch circuit."

Jim Port 02-19-2010 10:15 AM

The lights could just be wired ahead of or upstream of the GFI so there is no protection there. It does not necessararily mean a different circuit. Circuits start at a breaker. If one breaker turns off the lights and receptacles they are on the same circuit.

A GFI switch will provide the required GFI protection as well as acting like a switch. It looks like a GFI receptacle without the slots.

mbaughan 02-19-2010 10:36 AM

Thanks again, Jim. Much appreciated.

Last two questions, for now anyway... I see that there are two exhaust ducts in the attic already. I'm 99% that they are for an exhaust fan in a bathroom on the main level and the oven/range vent/fan in the kitchen. Both are ducted with PVC.

Any problem with tying into these pre-existing ducts?

Also, if I just install a fan, separate from the lights and not over the shower area, must it also be GFI protected?

Jim Port 02-19-2010 10:49 AM

If the fan is not over the footprint of the shower the GFI protection will not be needed.

I can't answer about the duct question, sorry.

secutanudu 02-19-2010 10:56 AM


Originally Posted by mbaughan (Post 402578)
Any problem with tying into these pre-existing ducts?

Sounds like a good question for the HVAC Forum

deniselhk 02-24-2011 09:21 PM

I am also going to install a bathroom light/fan combo and I was wondering how you ended up venting yours. Did you make a new hole or did you tie into the existing duct? Thanks!

mbaughan 02-25-2011 06:36 AM

I drilled a new hole. Tying into an existing duct would have required installing more elaborate ductwork than was prudent.

jscott3333 02-25-2011 07:29 AM

It looks like you already made the right decision.

I would not reccomend tying the exhaust fan into a kitchen exhaust, because depending on pressures inside and outside your home you could exhaust the kitchen vapors into the bathroom or vice versa, unless you used a dampener system of some sort. Although the benefit would be a bathroom that smells like fried chicken!

secutanudu 02-25-2011 07:55 AM

[quote=jscott3333;597652Although the benefit would be a bathroom that smells like fried chicken![/quote]

Or a kitchen that smells like...something else!

All times are GMT -5. The time now is 08:22 PM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1