Good Morning - On our front lawn is an old lampost. On the front (streetside)is a button (not really a button) that has threads on it. The size of this button is about 1/2" or so.

Has anyone ever seen this and know what it's meant for? My only conclusion is some sort of hook though I've never seen anything that would screw on.

I know it is an electrical lampost because on the backside is a covered outlet. It's very possible that what it was meant for is no longer available.

If this sounds familiar to anyone, I would be grateful to have this niggling question answered.

Best Regards,
Dawn

It's the photo sensor for the light. This keeps the light from burning during daylight. Depending on brand, it's held in place either by a threaded trim ring around the outside of the sensor, or a couple of small screws. In either style, to replace the sensor you must remove the light fixture from the top of the light post so you can reach inside the post from the top.

The sensors can go out fairly easily - a close lightning strike can kill one. When they go out, it's about a 50/50 chance that either the light will not work at all or the light will burn all the time. If this is a photo sensor, then when you look at the front of the 1/2" circle it will be clear glass with a zig-zag wire pattern inside. The other possibility is that all posts are made to hold the sensors but some post lights are controlled only by a switch and do not have a photo sensor. In this case, there is a plug used to cover the hole in the post.

Home stores carry the most common styles of sensors - most are around $10. It's a fairly easy fix to replace one if your post light is not working properly.

This message has been edited. Last edited by: Jaybee,

you can get one that screws into the light socket and the bulb screws into that. Easier fix

Look something like one of these?
http://www.bing.com/images/sea...FEE&selectedIndex=81

If the light is on a switch, just bypass the photocell. They aren't the most reliable pieces of electronics out there.