Automatic switch to provide power to aux bulb incase of main bulb failure?

Discussion in 'The Projects Forum' started by doh13, May 28, 2015.

  1. doh13

    Thread Starter New Member

    May 28, 2015
    What I am looking for or to build is some sort of automatic 110v plug in receptacle relay switch that will sense that a bulb has blown (or no power being used) and would then switch to an aux power receptacle that would send power to my aux bulb in in-case of a failure in the main bulb while I am away. I assume there would be some sort of relay setup that could achieve this. Any links or input would be greatly appreciated i am able to build this with help or i am willing to buy such a device already made if i know the name of the device which i know must be out there... BTW the lamps are 250 watt heat lamps for chickens and i want the aux lamp to power up automatically if/when the main bulb fails.

    I would like this set up for 2 reasons.

    1. My coup gets a too hot with 2 lamps running at once.

    2. It uses more energy to run 2 lamps =).
  2. crutschow


    Mar 14, 2008
    I don't know of any standard device to do what you want. :(
    The best I can think of is to use one of these Smart Strips to detect the bulb burning out.
    Wire one of the SWITCHED outlets to a 115Vac relay with SPDT or DPDT contacts (you can put the relay in a small plastic electrical component box).
    Wire the back-up bulb through one of the NC contacts to the 115Vac.
    Plug the primary bulb into the CONTROL outlet of the strip and plug the strip into 115Vac.
    Then when the bulb burns out, the strip will remove the power to the relay and the NC contact will power the back-up bulb.
  3. ebeowulf17

    Active Member

    Aug 12, 2014
    If temperature control is the ultimate goal, could you use a simple mechanical thermostat to control only the backup light? It would never turn on unless the main lamp failed to provide heat. I don't know if this one adjusts down to a low enough range to be useful, but I assume there are comparable ones available for different temperature ranges.
  4. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    Taking that mechanical thermostat a step farther, a snap-disc thermostat is small, cheap, and rated to switch 110 VAC. Wire it in series with one wire of an extension cord and place it near bulb #1. There might be a minute of darkness while it cools off enough to snap. Make sure to get one that opens on temperature rise. This is the less common option. For $5, here are some from a great surplus house:

  5. ScottWang


    Aug 23, 2012
    If you are not emphasize something then that is unnecessary to used the big font, we all get used to the standard fonts, if you need big font size to see, please just adjust for yourself in your screen, thank you.
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    Can't find it now but someone posted a simple device that would simply clamp around the cord (probably one conductor of it) and would trigger a relay when the current was below the setpoint..
    It was fairly cheap/simple non-industrial device..
  7. doh13

    Thread Starter New Member

    May 28, 2015
    Thanks guys you have all given me some interesting ideas with the thermostats / cut off switches etc.. i will do more research and i will be back. Mcgyvr if you happen to remember the device you speak of that sounds exactly like what i would be looking for.
  8. doh13

    Thread Starter New Member

    May 28, 2015
    sorry I did not realize i used any special fonts other than defaults, my typing looks the same as everyone elses and isn't big at all..
  9. ScottWang


    Aug 23, 2012
    You look them all the same, because I already modified to the standard.
  10. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    We had to have backup lamps for solar cell life testing, but we operated the lamps off of DC.

    It's still relatively easy. Start out with a current sensor such as this one:

    and at least a DPDT relay and a Normally Open (NO) switch. A 3PDT relay would give you an alarm contact, so you could, if you wanted, parallel all of the alarm contacts and wire it to a LED or lamp on the outside of the coop that at least one lamp needs service. A 120 VAC neon lamp can be used as a local indication that your on backup.

    In words you would wire the current sensor so it turns on the relay. It can't unless it has help, so a NO momentary switch is wired in parallel. That switch turns the main bulb on and then the sensor keeps it on.

    When the relay is engaged, the wiring is made so your your operating off the main lamp. If power fails and is restored, you will be operating off the backup lamp.

    In our case, we had indicators if we were operating off the backup lamp.

    Startup involves, pressing the button for each lamp until the indicator goes out. Once the backup lamp was on, we would switch the lamps with the backup being a new one. Our lamps had about a 40 hour continuous life.
    Last edited: May 31, 2015
  11. doh13

    Thread Starter New Member

    May 28, 2015
    Thanks for the idea keepitsimple that's an interesting way to do it thank you for the suggestion I will likely try to build something like this for future broods of chicks. But for now I may just use the thermostat idea
    ebeowulf17 suggested which I have access to since this seems to be the simplest/fastest to set up in a pinch as well. I will put it close to the main heatlamp bulb which is heating the floor below to about 92 f so if/when the bulb blows the thermostat will power on the Aux bulb and I wont have to worry about overheating them with 2 bulbs running or freezing them if the main bulb blows and i am not around. thanks everyone for all of the suggestions and ideas this forum is great!