this post was submitted on 01 Feb 2025
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What is this thing?

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Bought a house recently. Trying to figure out what this control knob could be for. I haven't had a chance to get the ladder out yet to test what turning it could do. Any ideas? It's on the west side of the house, if that could matter.

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[–] [email protected] 44 points 2 weeks ago (2 children)

It’s a light sensor not a control knob

[–] [email protected] 18 points 2 weeks ago

Photo sensor to be exact. I'm a residential journeyman and install these all the time. They can be wired to just about anything, mainly outdoor lights but sometimes Xmas lights as well. Pretty handy and super annoying

[–] [email protected] 14 points 2 weeks ago (2 children)

What would that be for? I'm assuming an outdoor light but those would have one built in or along its power connection.

This hypothesis can be easily tested: try shining a bright flashlight into it at night and see if some light turns off.

[–] [email protected] 13 points 2 weeks ago (1 children)

Could be wired to another outlet that’s intended for Christmas lights.

[–] [email protected] 10 points 2 weeks ago (1 children)

You're right, it's this or similar inside an electrical box.

[–] [email protected] 10 points 2 weeks ago

Thank you!!! I'll take a closer look once the snow melts and try to figure out which lights it could be connected to.

[–] [email protected] 6 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

Having a central photocell is super common. Only in the last few years have devices have them integrally since they became cheap. But sometimes they are still controlled by a central timer/photocell as well.

And it’s never put “along the power source” a central photocell should be in the shade on the setting side of the sun. Put it on the east, and the lightsll come on too early.

[–] [email protected] 5 points 2 weeks ago (1 children)

Put it on the east, and the lightsll come on too early

East seems more logical since people are more active (and likely to enjoy the lights) between 6-8 PM than 4-6 AM so unless you have a timer, it seems practical to turn the sensitivity to max and point it east so the lights come on early and shut down as soon as it dawns.

[–] [email protected] 2 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

The “codes” are for commercial areas where the public is assumed to be more less always there. Think like condo or mall parking lots.

Your house, you can do whatever you want.

[–] [email protected] 0 points 2 weeks ago (1 children)

I'm just guessing, we barely do Christmas lights in this country. People usually use a timed socket for ornaments in their window or wrapped around a tree outside. Light sensors obviously exist here, they are used as part of PIR units to control floodlights. Towns use installations on streetlights, controlled by a similar mechanism.

Why would anyone use energy for a festive atmosphere at 2AM on mall parking lots? Even their streetlights usually shut down at midnight.

[–] [email protected] 3 points 2 weeks ago* (last edited 2 weeks ago)

Some malls have drugstores that operate 24/7, you flood it with light to prevent crime as well.

I’ve never seen a public lot not lit 24/7 in NA. The dark attracts crime, can’t be seen well nor recorded in the dark. So given the opportunity, they’ll pick the dark lot over the lit one. So to deter, you light it up, but as said, there’s usually some business open 24/7 anyways, or you don’t know what tenants are there at any given time, so you defer to the safest. All the time.

[–] [email protected] 15 points 2 weeks ago (1 children)

It controls the volume of water that is allowed through the gutter right there.

[–] [email protected] 7 points 2 weeks ago

Yeah it’s a gutter dimmer switch.

[–] [email protected] 13 points 2 weeks ago

The gutter prostate

[–] [email protected] 12 points 2 weeks ago

Attitude adjustment for The Moon.

[–] [email protected] 7 points 2 weeks ago

It releases the landing gear.

[–] [email protected] 5 points 2 weeks ago (1 children)

Turn that thing to 11, the roof will be on fire!!!

[–] FiddlersViridian 6 points 2 weeks ago (1 children)

The roof? The ROOF!? The roof is on FIRE!?!

[–] [email protected] 3 points 2 weeks ago

We don't need no water let the motherfucker burn