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mmccarty 08-24-2009 11:15 PM

Need lighting control solution
I have a poultry barn that needs 12 to 16 hours a day of light with the lighting period ending at dusk each day. I currently have a 24 hr time clock with a pair of on/off trippers that need to be adjusted every week or two as the sunset time changes. How can I set up an astronomical time switch to turn on the lights a set period of time before dusk and off again at dusk? Most of the time switch instruction manuals I have read (Intermatic/Tork manuals) assume that you want to turn on a load near dusk and turn it off after a set time or at dawn. The best solution I can come up is to have the dusk/on signal power an on-delay timer that drops the lighting contactor at dusk and picks it up again 8 to 12 hours hours later. I would just need to set the delay timer to the amount of darkness needed each day. Not a very elegant solution nor a very good one should there be a power interruption, it would reset to the off position. Anyone know of a particular electronic time switch that would work or another control solution?

theatretch85 08-24-2009 11:41 PM

Try this timer by Intermatic:

I have one in use at my parents place for an outdoor outlet intended for vehicle block warmers. You can set the "ON" time to be a set time, dusk, or dawn and same for the "OFF" time as well. I'd say it works pretty well, the only thing is it uses a battery to keep the time and to activate the relay inside the timer. Since we don't experience many power outages here it would be nice if the battery was merely a "backup" battery to keep the programs and the time in the event of a power outage.

Also, the front cover of this switch when pressed activates the load, and has the ability to connect a remote switch to be configured in a 3-way switch configuration. This particular timer only needs a single pole remote switch to accomplish a "3-way" switch configuration.

mmccarty 08-24-2009 11:54 PM

That answers one question, that these timers can be set for on or off events to occur at dusk or dawn and not just dusk/on dawn/off, but how do I get it to turn on the lights at a set period of time before dusk? For most of the year I need 16 hours of light everyday, but always turning off at dusk. This time of year as the the sun is setting earlier and earlier I need the lights to turn on earlier and earlier in the morning to maintain that 16 hours of lighting.

frenchelectrican 08-24-2009 11:56 PM

Here is the other verison but really good one

that you can set the time and it will automatic adjust the on and off time mode where you want to set up.

I know they are not cheap as other 7 day timers are but it worth it escpally something like your poultry useage there.


mmccarty 08-25-2009 12:21 AM

Thanks Marc, I've looked at the manual for that timer, but the crux of the problem is not only do I need to turn the lights off at dusk, but I also need to turn them on 16 hours prior to dusk everyday. The on time is not a fixed time, but a fixed period of time before dusk. Many of the time switches allow you to set an event within two hours of of dusk or dawn (e.g., turning on lights 30 minutes before sunset), but I haven't come across any that allow an offset of 16 hours, or at least the specific details of such an option aren't stated in the specs or installation manuals that I've come across.

frenchelectrican 08-25-2009 12:36 AM


Wowie I can see where this going however I think there is other item may suit your need due you need fixed off shedule but on shedule will varies a bit so here a link

If that don't suit what you need let me know myself or other members in here will find a way to get it set up what you need.


PaliBob 08-25-2009 04:30 AM

2 Attachment(s)

Originally Posted by mmccarty (Post 318996)
The best solution I can come up is to have the dusk/on signal power an on-delay timer that drops the lighting contactor at dusk and picks it up again 8 to 12 hours hours later. I would just need to set the delay timer to the amount of darkness needed each day.

The highlighted time will not be a constant but will vary throughout the year. I see the practical requirements to be 16 hours ON triggered each day so that the OFF time will be the same as the Astronomic Sunset time.

  • 'Chicken ON' time to Sunrise will vary
  • Sunset to 'Chicken ON' time will vary
  • 'Chicken On' Time must stay at 16 Hours (or some other constant)
M, I think you are on the right track in thinking that besides an Astronomic Timer you will need something between the Timer (used to provide the Sunset trigger) and a 16 hr contactor timer.

I don't see a solution using a delay timer or by using either of the Intermatics.
1) My first suggestion would be to call Intermatic and explain the 16 hr ending at dusk requirement to see whether or not they have a suggestion.
2) Ask around to see how others deal with "Chicken Time"

The only other possibility that I see is to dedicate a cheap desk top PC as a light controller. You could ask for computer help over in 'PC Repairs & upgrades"

My Astronomic Timing Diagram can easily be inverted to provide leading edge Sunset trigger by setting the Intermatic to turn ON at the end of the 16 hr cycle (at Sunset).

micromind 08-25-2009 06:17 AM

How about a photocell that turns the lights off, and starts a timer. 8 hours later, the lights come back on again.


PaliBob 08-25-2009 07:13 PM


Originally Posted by micromind (Post 319041)
How about a photocell that turns the lights off, and starts a timer. 8 hours later, the lights come back on again.


Thanks to Micromind, I have rethought this problem since Rob is right the 8 hr off time can be achieved by using a time delay relay.

Dusk occurs at all different times through the year but the Dusk trigger will always be 24 hours after Dusk the previous day. this means that the OP, and others who suggested Intermatic Astronomic times were all on the right track. If the Dusk trigger can engage an 8 hr delay in the lighting circuit then M's requirement will be met for Lights ON for 16 Hours ending at dusk.

Unfortunately the Intermatic E1600 can only be programmed to
  • A Specific On/OFF time, Or
  • ON or OFF at Dawn, or
  • ON or OFF at Dusk

But there is no relative setting. That is it can't be set to Dusk + 8 hrs.
see section 5:

An Astronomic timer would be more consistent than a photocell to generate a Dusk trigger because the photocell would be subject to the vagaries of the weather. The Intermatic ET1600

Delay timers for long delay times are expensive but the types that have digital thumbwheel switches to set the time and have a digital display are accurate to the minute and easy to verify proper operation.


mmccarty 08-25-2009 09:13 PM

Thanks for all of the replies. The Intermatic time switch that Marc mentioned will do it, it allows you to set an off interval of up to 7 days after an astronomic event, but it runs $300, is overkill to program two events, and does not reset very well after a power outage. It waits until midnight after power is restored to resynch its programming (which is pretty crappy for an electronic time switch costing that much). I could do the same with a cheaper astronomic timer and a time delay relay, but like I said in the original post, when the power is restored the setup would revert to another set period of darkness, instead of to the last state. The more I think about it and see the lack of commercial options, it would probably be better (and a lot cheaper) to just use a custom programmed microprocessor with battery backup. A real-time clock, a quick lookup table and a little math would be a pretty simple solution.

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