# Questions about wiring light and fan together in bathroom **URL:** \ **Category:** Factual Questions\ **Created:** [August 16, 2019, 10:00pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768 "2019-08-16T22:00:29Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 17, 2019, 3:06am UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/21 "2019-08-17T03:06:03Z")
> [@aceplace57](#): > > I’m having trouble understanding the problem. My family rarely uses the bathroom fan. > > It’s never caused any mold problems. I’m going to guess that Portland has a lot more humidity than Arkansas. Those cool clammy days make it a pain to dry the air in your house. No one wants to run the AC when it’s 65 out, just to dehumidify the house. So any steam you can suck out of the bathroom and send outside will make the house more comfortable and the windows less likely to condensate (which can make it’s way to nearby surface and help mold and mildew form). > [@](#): > > You can wire the fan and light together. Constantly turning it on/off will shorten the life of the fan. > > It may shorten bulb life too. There’s going to be a current surge as the fan motor starts. Those spikes may be a problem for the bulbs. Bulbs are seeing the voltage fluctuate 60 times a second, a few more times a day isn’t going to hurt them. Besides, every thing in your house sees that slight voltage drop every time something else is turned on. You may not notice it, but it still happens. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [August 17, 2019, 5:26am UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/22 "2019-08-17T05:26:01Z")
> [@GESancMan](#): > > I pulled the plate off, and I can see the wires. I was thinking I’d have to pull the actual switches out to get to the wiring, which is why I was reluctant. Anyway, they look rather thick. I used a sewing tape measure, and they appear to be just under 1/8 inch in diameter. But according to a couple of charts I looked up, that would be 8 or 9 gauge. Are the charts not counting the insulation? > > t. Yes it will be necessary to pull the switches to change the wiring. Insulation is not part of the measurement of wire. If the light is on a 15 amp circuit breaker then you can use #14 or larger wire any where in the circuit. Using #12 will be OK because it is rated at 20 amps or less, 15 is less than 20. But you should not use #14 on a circuit protected by a 20 amp breaker. ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [August 17, 2019, 11:57am UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/23 "2019-08-17T11:57:36Z")
> [@EdelweissPirate](#): > > What makes you nervous about that? Are you more worried about electrocution or killing your phone by dropping it in the tub? > > Neither should bother you much, IMHO. My iPhone XS is rated IP68 (30 minutes under 2 meters of water) and even the years-old iPhone 7 is rated IP67 (30 minutes under 1 meter of water). The thought of dropping it. I had no idea phones were so water resistant. mmm ---
**Author:** ![albino\_manatee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/albino_manatee/32/2_2.png) [@albino\_manatee](https://boards.straightdope.com/u/albino_manatee)\ **Post date:** [August 17, 2019, 12:44pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/24 "2019-08-17T12:44:14Z")
> [@GESancMan](#): > > \*" No matter how much we explain, plead, or yell and scream … > > … told me that code states that bathrooms are supposed to … > > … My condo was built in the mid ‘70s, and we bought it three years ago … "\* imo … your _‘project’_ should be done by a licensed electrician. you stated it’s a condo … therefore, **hoa** needs to be involved _(it’s in your contract)_ … and the **city** also needs to be involved. even if you would do the work yourself … a **licensed electrician** needs to inspect and give written approval. i would do three things: [ul] [li]i’d get an approval with the hoa before commencing with the project[/li][li]i’d have a licensed electrician inspect/approve your handiwork[/li][li]i’d also get a low-sound fan.[/li][/ul] by that, you are showing civility toward your daughter … you might also be saving countless innocent lives … by not inadvertently starting a fire. an alternative … is to have a heart-to-heart talk as a family circle … explaining why the fan needs to be used. and this does not entail _‘yelling’_ or being uncivil. there’s other places for the daughter to play video … like her own bedroom. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [August 17, 2019, 1:54pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/25 "2019-08-17T13:54:12Z")
> [@aceplace57](#): > > You can wire the fan and light together. Constantly turning it on/off will shorten the life of the fan. The fan is a simple induction motor. Those little motors don’t even employ a start capacitor. Bottom line is that it doesn’t care about power cycling; the only thing that matters for the fan is hours of run time, the warmth from which slowly dries out the tiny felt-pad oil reservoirs that keep the spindle bushings lubricated. The line is supplying 120VAC to both the fan and the light socket. A current surge through one device will not cause a current surge through the other device. Moreover, the current “surge” through the fan’s motor at startup isn’t a single large spike of high current; it’s an enduring period of time during which the AC current oscillates with a large magnitude, gradually decreasing as the fan approaches normal operating speed. ---
**Author:** ![Drum\_God](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drum_god/32/44_2.png) [@Drum\_God](https://boards.straightdope.com/u/Drum_God)\ **Post date:** [August 17, 2019, 4:31pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/26 "2019-08-17T16:31:33Z")
Your daughter sounds like my daughter. We didn’t have this particular issue, but we had plenty of others. Because I’m as hard-headed as she is, it took me a while to learn that, as hard as I was working to manipulate conditions to gain compliance, she was working just as hard in the other direction. My daughter (now an adult) was and is a very adaptable and resourceful person. If we had had this particular problem and I employed the solution you’re proposing, she would have simply found a way around it. My daughter would have bathed in the dark, left the door open, brought in a light from somewhere else, gotten a flashlight or lantern, or any number of other solutions. Take it from one who has survived a teenaged daughter. You won’t win. Find another way. By the way, if the objection is to the noise from the fan preventing her from hearing her videos, I encourage the purchase of a quieter fan. That may end up pleasing both of you and solving the problem. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 17, 2019, 4:43pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/27 "2019-08-17T16:43:54Z")
> [@Drum\_God](#): > > By the way, if the objection is to the noise from the fan preventing her from hearing her videos, I encourage the purchase of a quieter fan. That may end up pleasing both of you and solving the problem. I know the OP mentioned not wanting to attempt changing the fan, which can be a daunting task. However, if you can find one that’s the same size (even better if it’s the same brand), you can often replace just the chassis/motor. When you take the grill off the fan, you’ll see something like [this](https://www.juliavaconsin.com/bathroom/fasco-bathroom-fan-motor-replacement/11_fasco-bathroom-fan-motor-replacement_bathroom-exhaust-fan-motor-repair-and-maintenance-best-furniture.jpg), the motor, blade and flat part everything is mounted to drops out and you can replace it with a new one ([looks like this](https://i5.walmartimages.com/asr/cdf43997-65d3-4d42-bed8-307a804be481_1.f9abf83bc5c677865e2bb2cd43f97f2c.jpeg)). Replacing a ceiling fan can easily take an hour even if you’ve done it plenty of times before. Replacing just this part is 10 minutes, most of which is spent just trying to get the original one popped out. And, you’ll note, is plugged in with a normal looking plug into a normal(ish) looking outlet, all inside the fan. Now, if that fan has been up there for 40 years, it may not look like this, but if it does, it’s an easy and cheap upgrade. ---
**Author:** ![GESancMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gesancman/32/2923_2.png) [@GESancMan](https://boards.straightdope.com/u/GESancMan)\ **Post date:** [August 17, 2019, 5:51pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/28 "2019-08-17T17:51:15Z")
> [@Drum\_God](#): > > Your daughter sounds like my daughter. We didn’t have this particular issue, but we had plenty of others. Because I’m as hard-headed as she is, it took me a while to learn that, as hard as I was working to manipulate conditions to gain compliance, she was working just as hard in the other direction. My daughter (now an adult) was and is a very adaptable and resourceful person. If we had had this particular problem and I employed the solution you’re proposing, she would have simply found a way around it. My daughter would have bathed in the dark, left the door open, brought in a light from somewhere else, gotten a flashlight or lantern, or any number of other solutions. > > Take it from one who has survived a teenaged daughter. You won’t win. Find another way. > > By the way, if the objection is to the noise from the fan preventing her from hearing her videos, I encourage the purchase of a quieter fan. That may end up pleasing both of you and solving the problem. Yes, my daughter is like this, to an extent. There have been many cases in the past where we’ve had to force compliance by taking away the choice. She is not all that resourceful, though. She’ll probably bathe in the dark a few times, then decide it’s not worth it. > [@Joey\_P](#): > > I know the OP mentioned not wanting to attempt changing the fan, which can be a daunting task. However, if you can find one that’s the same size (even better if it’s the same brand), you can often replace just the chassis/motor. When you take the grill off the fan, you’ll see something like [this](https://www.juliavaconsin.com/bathroom/fasco-bathroom-fan-motor-replacement/11_fasco-bathroom-fan-motor-replacement_bathroom-exhaust-fan-motor-repair-and-maintenance-best-furniture.jpg), the motor, blade and flat part everything is mounted to drops out and you can replace it with a new one ([looks like this](https://i5.walmartimages.com/asr/cdf43997-65d3-4d42-bed8-307a804be481_1.f9abf83bc5c677865e2bb2cd43f97f2c.jpeg)). > Replacing a ceiling fan can easily take an hour even if you’ve done it plenty of times before. Replacing just this part is 10 minutes, most of which is spent just trying to get the original one popped out. And, you’ll note, is plugged in with a normal looking plug into a normal(ish) looking outlet, all inside the fan. > > Now, if that fan has been up there for 40 years, it may not look like this, but if it does, it’s an easy and cheap upgrade. Yes, the fan is old, I’m guessing at least 20 years, if not 30 or 40. It looks something like [this](https://i.ytimg.com/vi/H7BvLn3kHPs/hqdefault.jpg). Since several people have suggested it, I think I am going to wait and replace the fan. Back in the OP, I said I _suspect_ her reason is the noise… I don’t know that, because she won’t tell us why. She just says “I don’t know” over and over. So maybe we need to talk with her, and tell her we can get a quieter fan if the noise is the issue. _Maybe_ then she’ll admit that’s the reason. If it really is, but I can’t think of why else she would refuse to turn the fan on. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 17, 2019, 5:54pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/29 "2019-08-17T17:54:43Z")
> [@GESancMan](#): > > Yes, the fan is old, I’m guessing at least 20 years, if not 30 or 40. It looks something like [this](https://i.ytimg.com/vi/H7BvLn3kHPs/hqdefault.jpg). It’s is square and some ‘normal’ brand like NuTone or Broan, there’s a good chance it’s standard. You can easily pop the motor and mounting plate out of it and take it to Home Depot or Lowes. They sell the replacements. Even if you don’t get something they have, you’ll be able to tell if it’ll fit and get an idea as to how/what size to order online. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [August 17, 2019, 9:12pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/30 "2019-08-17T21:12:02Z")
> [@GESancMan](#): > > What about mixing the wiring? Is it ok to use 12-gauge for the pigtail if the wiring in the walls turns out to be 14-gauge? Don’t. It’s always OK (legally, code-wise, electrically) to use a bigger wire than required. But the risk is that some future homeowner, like you, is modifying the wiring, and looks at the wire size to see what amperage the circuit can handle. He see the #12 pigtail and thinks it’s a 20A circuit, without digging back in the box to notice the #14 15A cables running through the wall. And so he wires something incorrectly, and burns down the house, and maybe some occupants. So just don’t mix wire gauges. A foot of #14 wire is about 20¢ at a hardware store – spend that. (Far less than the 20A switch you were considering.) P.S. each wire in the box will have the wire size marked all along it. Pull out enough to see, clean it off, and the wire gauge will be printed on the insulation. Then you know for sure. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [August 17, 2019, 10:05pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/31 "2019-08-17T22:05:21Z")
I find the sound of most bathroom fans at least moderately unpleasant; and some bathroom fans make a noise at a frequency that sets my teeth on edge. The bathroom at the town hall where I frequently go to meetings is like that; and it’s wired on one switch with the light. It’s barely endurable for long enough to pee; I certainly couldn’t stand to take a bath with that thing running. Obviously the noise doesn’t bother most people. But maybe your daughter’s like me in this, but can’t figure out how to express that the problem’s not the volume level, but the frequency. If it’s that, changing the fan might or might not help, as the new one might also hit the same frequency. Why not just ask her to run the fan for a while after she’s done in the bathroom, if the humidity’s really that bad that not running it is causing problems? My bathrooms have windows in them. 😃 But maybe it’s impractical to put a window, or even a vent, into hers. ---
**Author:** ![Sicks\_Ate](https://avatars.discourse-cdn.com/v4/letter/s/258eb7/32.png) [@Sicks\_Ate](https://boards.straightdope.com/u/Sicks_Ate)\ **Post date:** [August 17, 2019, 10:08pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/32 "2019-08-17T22:08:57Z")
> [@thorny\_locust](#): > > Why not just ask her to run the fan for a while after she’s done in the bathroom, if the humidity’s really that bad that not running it is causing problems? Yup. Good solution. ---
**Author:** ![GESancMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gesancman/32/2923_2.png) [@GESancMan](https://boards.straightdope.com/u/GESancMan)\ **Post date:** [August 17, 2019, 11:40pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/33 "2019-08-17T23:40:46Z")
> [@Tim\_T-Bonham.net](#): > > Don’t. > > It’s always OK (legally, code-wise, electrically) to use a bigger wire than required. But the risk is that some future homeowner, like you, is modifying the wiring, and looks at the wire size to see what amperage the circuit can handle. He see the #12 pigtail and thinks it’s a 20A circuit, without digging back in the box to notice the #14 15A cables running through the wall. And so he wires something incorrectly, and burns down the house, and maybe some occupants. See, this never would’ve occurred to me. If I do this project, I won’t mix the gauges. > [@thorny\_locust](#): > > I find the sound of most bathroom fans at least moderately unpleasant; and some bathroom fans make a noise at a frequency that sets my teeth on edge. The bathroom at the town hall where I frequently go to meetings is like that; and it’s wired on one switch with the light. It’s barely endurable for long enough to pee; I certainly couldn’t stand to take a bath with that thing running. > > Obviously the noise doesn’t bother most people. But maybe your daughter’s like me in this, but can’t figure out how to express that the problem’s not the volume level, but the frequency. > > If it’s that, changing the fan might or might not help, as the new one might also hit the same frequency. Why not just ask her to run the fan for a while after she’s done in the bathroom, if the humidity’s really that bad that not running it is causing problems? > > My bathrooms have windows in them. 😃 But maybe it’s impractical to put a window, or even a vent, into hers. You could very well be right! My daughter is on the autism spectrum, and ADHD to boot, and she does have sensory issues. She has always turned the fan on when she leaves the bathroom. But that’s not good enough. By then, there is water running down the walls. The light fixture has rust on it, which wasn’t there when we bought the place two and a half years ago. Having the fan running from the start of her shower would alleviate the humidity somewhat. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [August 17, 2019, 11:52pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/34 "2019-08-17T23:52:28Z")
> [@GESancMan](#): > > \*\*You could very well be right! My daughter is on the autism spectrum, and ADHD to boot, and she does have sensory issues. > \*\* > She has always turned the fan on when she leaves the bathroom. But that’s not good enough. By then, there is water running down the walls. The light fixture has rust on it, which wasn’t there when we bought the place two and a half years ago. Having the fan running from the start of her shower would alleviate the humidity somewhat. Go for a new fan. A good new one makes very little noise. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [August 18, 2019, 12:45am UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/35 "2019-08-18T00:45:02Z")
Regarding fan noise: a handyman who did some work on my house a few years ago mentioned this issue with some customers of his. They were very noise-sensitive (both orchestral musicians) and needed a bathroom fan, but couldn’t abide the noise. So he installed one where the actual fan was attached by the exit opening at the wall of the house, with about 12 feet of ducting running through the attic and connecting to a ceiling duct in the bathroom. So the only noise in the bathroom was from the air going through duct. This cost more – it required a different type of ventilation fan instead of a bathroom fan, and extending the electrical connection across the attic to the fan location, but it kept the bathroom very quiet, which was important to this couple. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [August 18, 2019, 4:54pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/36 "2019-08-18T16:54:48Z")
> [@GESancMan](#): > > You could very well be right! My daughter is on the autism spectrum, and ADHD to boot, and she does have sensory issues. > > She has always turned the fan on when she leaves the bathroom. But that’s not good enough. By then, there is water running down the walls. The light fixture has rust on it, which wasn’t there when we bought the place two and a half years ago. OK, that’s a mess. But making it intolerable for her to use the bathroom, by rewiring the existing fan, wouldn’t solve the problem. It would probably only result in her using the bathroom in the dark, or by flashlight, or not at all – I doubt you want to live with the results of ‘not at all’. I’ll assume that it’s impractical to rebuild the bathroom so as to make the problem go away, either by making all of the interior including fixtures water resistant, or by adding openable windows. So I’d suggest finding a brick-and-mortar store that sells the fans and has some hooked up to demonstrate sound levels, and going there accompanied by your daughter, and having her choose which fan(s) don’t cause her the problem. Just getting the decibel ratings won’t be enough, because it probably is a frequency problem and not a volume problem. If there is no such store in the area, then try asking her to turn on the fan in bathrooms belonging to friends, and when she identifies one or more that don’t cause the problem, asking them what fan they have. That might run into the difficulty that the friends may have no idea, and/or that the particular models may not be on the market, or I suppose that she might find no such fan. And/or maybe there’s advice on the subject on websites discussing sensory problems? [ETA: or maybe try Tim@T-Bonham’s solution.] But I really, really wouldn’t try to solve the problem by trying to force her to be exposed to a sound she can’t stand. Especially in a place that ought to be a refuge. ---
**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\ **Post date:** [August 18, 2019, 6:56pm UTC](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768/37 "2019-08-18T18:56:43Z")
The real problem here is the humidity. Solve this by setting the water heater to tepid. Or turn it off. She won’t linger in the bathroom. Sure, everyone in the house suffers, but it’s the long game - when it’s time for her to leave home, she’ll be ready to get the hell out of there. In the meantime, put the money from the energy savings to your wine budget. It’s not all suffering. [Previous page](https://boards.straightdope.com/t/questions-about-wiring-light-and-fan-together-in-bathroom/838768.md?page=1)