How To Solve That Awkward Restroom Situation

May 15, 2018
Tech Tuesday

Have you ever been in that awkward situation where there are two people standing, and only one seat left? I’m pretty sure we’ve all been there. Maybe it was a time you were playing musical chairs, or a party at your friend’s house that didn’t have enough seats, or even a movie when the row wasn’t quite long enough. Whatever the case, it inevitably ended with you awkwardly sitting on someone’s lap (or vice verses), or with you desperately clenching one cheek as you and the other try to share the seat by sitting on the edge, or in the worst of cases, you falling on the ground and injuring yourself (Thanks for the scars and traumatic memories, Musical Chairs).

I’ve thought long and hard about this. After many sleepless nights I’ve finally come to this one single conclusion: This must be the way restroom lights feel when there’s only one fan. You know what I’m talking about. You’ve got two light switches for the restrooms, one for the men’s and one for the women’s, but only one fan to share between the two. It seems like no matter which way you look at it, you can only have one switch control the fan. If you’re not careful and try to wire it so both switches control the fan, you could end up having one light turn off or on when you don’t want it to, and no one likes doing their business in the dark.

Luckily, while us humans are doomed never to escape this awkward situation, there is hope for restroom lights. This hope comes in the form of two relays. By controlling the coil of each relay with the two separate lighting circuits and wiring their contacts in parallel, the two relays can act as a sort of OR gate for the restroom fan. This will make it so that if one restroom light is on, the fan will also be on.

Here’s a diagram for you visual learners out there:

Note that while this diagram uses the RIBU2C, it can be accomplished using any two relays. This application can also be expanded for as many restrooms you have, such as the case of having an additional unisex restroom. All you would need to do is add a third relay. If you need help picking out a relay for this application, be sure to check out one of my previous blogs here or just call us at tech support and we’ll find you the relays you need.

Now go do your good deed for the day and save restroom lights from the awkward situation of trying to share a fan.


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About the Author

Tym Moore is an Electrical Engineer who hails from the best state of Colorado.
He graduated from Colorado State University in 2017 and moved to Indiana shortly afterward to marry his now wife. Outside of work, Tym spends most of his time driving back home, and complaining about how flat Indiana is.

Be sure to give Tym a call for tech support. He will always do his best to find a solution for you.