# Streetlamps **URL:** \ **Category:** Factual Questions\ **Created:** [February 21, 2003, 8:53pm UTC](https://boards.straightdope.com/t/streetlamps/156623 "2003-02-21T20:53:27Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![bodhi](https://avatars.discourse-cdn.com/v4/letter/b/49beb7/32.png) [@bodhi](https://boards.straightdope.com/u/bodhi)\ **Post date:** [February 21, 2003, 8:53pm UTC](https://boards.straightdope.com/t/streetlamps/156623/1 "2003-02-21T20:53:27Z")
I have observed numerous times that many streetlamps go on and off at intervals. What exactly is the point of turning off a streetlamp at random intervals? Are they trying to conserve energy, are the bulbs bad - what’s the deal here? You would think a streetlamp would be more useful if it stayed on continuously until dawn. – Charlie R., Brooklyn, NY ---
**Author:** ![Tapioca\_Dextrin](https://avatars.discourse-cdn.com/v4/letter/t/3d9bf3/32.png) [@Tapioca\_Dextrin](https://boards.straightdope.com/u/Tapioca_Dextrin)\ **Post date:** [February 21, 2003, 9:02pm UTC](https://boards.straightdope.com/t/streetlamps/156623/2 "2003-02-21T21:02:17Z")
Welcome to the Boards **bodhi**. Many people including the master himself have noticed the same thing. Cecil, being Cecil, decided to find out the truth. [The bulb is indeed on the way out](http://www.straightdope.com/classics/a4_047.html). ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [February 21, 2003, 9:04pm UTC](https://boards.straightdope.com/t/streetlamps/156623/3 "2003-02-21T21:04:35Z")
3 things 1\> If you are referring to sodium vapor lamps - they tend to do this near their end of life. If you want the technical details let me know. 2\> Manytimes the photo detectors (to turn on the lamps at dusk) are not properly positioned. So the sodium vapor lamp lights up and reaches a “certain light level” and trips itself off. 3\> There are timers designed to go on and off at random intervals to surprise/scare the bad guys trying to invade your property. Don’t ask me why it should scare them. ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [February 21, 2003, 9:06pm UTC](https://boards.straightdope.com/t/streetlamps/156623/4 "2003-02-21T21:06:38Z")
:smack: should have searched before posting. thanks tapioca dextrin.