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Landscape Lighting Automation – Photocells VS Astronomical Timers

For years the landscape lighting industry has relied on a number of methods to automate when low voltage transformers would turn on and off. Without this automation the system would have to be manually switched on every evening and off when desired, which is a daunting task to ask of anyone. Basic mechanical timers were originally installed within the transformers to provide some level of automation. Many of these timers would allow you to set multiple “on” of “off” times by inserting small pins beside the desired time on a mechanical dial. These timers were definitely better than nothing, but as you can imagine, they were less than ideal. If for any reason you lost power, time would stand still and your settings would be incorrect. The next thing you knew, it’d be 8 o’clock at night and you’d be in sitting in the dark!

Both Daylight Savings Time and the subtle changes in sunrise / sunset that happen daily would also bring about similar frustrations. Sometimes you’d be left in the dark, other times you’d look over and see lights shining in broad daylight. Since then, there have been many products that have given us much more control and programmability for the automation side of our landscape lighting systems. As you could imagine with anything technological, new and improved products are being designed and invented every day. The sky’s the limit on what you could do if you were willing to shell out the appropriate amount of cash to accomplish your automation goals. However in this blog, I’m going to focus on two widely used methods of automation. Almost every system installed today comes with either a photocell or an astronomical timer. Below I will quickly describe what each one does and which one I lean towards using in the projects I’m working on.

Photocells are broadly used and very popular in low voltage systems. They are small devices that use light to regulate the flow of electrical current. In other words, when light hits the sensor it turns the system off. In the absence of light, the current is then allowed to flow as normal and the system turns on. These are also widely used for street lights because it’s a simple formula: On at night, off during the day. The problem with that formula and a landscape lighting system is that some applications require an “off” period at night, typically to save on electricity. For this reason, digital and mechanical timers are often used in conjunction with photocells to allow a programmable “off” period. The photocell can be used at dusk to turn on the system while the timer turns it off at a desired time: 10pm, 12am, 2am, etc. You can also set the timer to turn the system back on in the morning, say around 5am so that you can appreciate it when you wake up. The photocell would then turn off the system at dawn and keep it from turning on until the cycle begins again that evening. Either of these scenarios are actually pretty amazing because you no longer have to adjust the on / off events to match the ever changing sunrise and sunset times. Of course, if you use a mechanical timer, it would need to be reset after daylight savings or if you ever loose power to the outlet, but in theory this setup works wonderfully! Photocells make it very easy to control when your system should be on and off based on the amount of light is sees. Pretty amazing technology if you ask me! However there are some downsides to using photocells that should be mentioned.

First off, durability. The jury’s still out on how long these guys are supposed to function properly. If I were to guess, most of the photocells that I’ve had to change out were about 2 years old. For what they do, this may be an acceptable time frame and knowing that they won’t last forever may not be that big of a deal.

Secondly, location. Many times your transformer is installed in somewhat hidden or inconspicuous locations, say behind some foundation plantings on the side of your home. The amount of light that is able to shine on these locations can change overtime, mainly because of growing plant material. When that plant grows and blocks the photocell, you may find that the lights come on earlier, stay on longer or simply never turn off. When this happens your only options are to trim the bushes or extend the photocell to an area where it can receive the appropriate amount of light. I have seen instances where neither of these options are desirable…which leads me to my next topic.

Astronomical Timers are becoming more and more popular as people begin to learn what they do. Now if you read the name and automatically begin to think of signs and horoscopes, that’s a completely different thing. Astronomy is a scientific discipline that studies objects beyond the Earth’s atmosphere, unlike its non-scientific, pseudo-psychological, future predicting cousin…Astrology. So now that that’s clear, what in the world would Astronomy have to do with my low voltage lighting system? Simple…the Sun! An Astronomical timer uses a pre-programmed database of times for sunrise and sunset to tell your system when to turn on and off. All you have to do is tell the timer where you are in the world, the time / date, and when you want your lights to shine. That’s about as easy as it comes – set and forget. It even gives you an option to automatically adjust for Daylight Savings Time. They’re perfect for applications where light may be an issue, as described above. I’ve seen transformers in garages, basements, crawlspaces and even boathouses. Not that I would recommend putting your transformer indoors, but in those instances, photocells are much more difficult to use effectively. Another noteworthy benefit to astronomical timers are their customizability. You can easily program on / off events specific to your desired uses. You may want your system to stay on longer on the weekends or a specific night of the week. And finally, as with many digital timers, they typically have a battery backup which helps save your settings if the outlet looses power.

More advanced techniques can be used to either control zones of lighting or to give remote control capabilities, but in most residential and commercial settings, one of the two automation techniques above are all that’s needed. Between Photocells and Astronomical Timers, I tend to lean towards the timer in most applications. The longer lifespan and increased customization when paired with a wider range of acceptable uses makes it a no-brainer for me. However, photocells do still have their place in the market and can be very effective when used properly. In the end you’ve still got a system that knows when to come on and when to turn off. What more do you need?

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Stay tuned for more professional landscaping tips from Hyatt Landscaping, Inc! If you enjoyed this article, please comment below and be sure to “like” us on Facebook. Thanks!!!

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