Outside lights (commercial) controlled by photo-eye and timer-clock

[sw_ross]

Was doing work at a business yesterday that I hadn't done work at before, so I wasn't totally up to speed on the buildings layout. In addition to some miscellaneous repairs they asked me to look at the outside light by the front door as it wasn't on when the head guy got to work that am.

Long story short, when I looked into how the outside lights were controlled I found a photo-eye and a timer-clock set up in series with each other to control a contactor. I'm trying to understand the design thoughts that would go into setting this up in that manner.

I can see the photo-eye and timer-clock being setup in parallel so that if you had a really dark day (stormy, cloudy, etc.) it would turn the lights on outside, or the timer-clock would turn the lights on at pre-set clock times (night-time).

I'm not sure I understand the benefits of setting them up in series. Can someone tell me what I'm not seeing?

Thanks, Sky

 

[iwire]

If you set them up in series the lights can only run when it is dark.

So for example you would set the timer to turn off at a 11PM and turn on at 5AM.

That way the lights would turn on at sunset, off at 11 PM, on again at 5AM and off at sunrise.

 

[kwired]

Bob nailed it. If for some reason you don't want them to run all night you put the timer in series.

Minimal security lighting wouldn't be a good idea to do this, but maybe you turn off excess lighting not needed after business hours with a timer. Seen this done on signs also where they are only desired to be illuminated when dark and during business hours.

 

[iwire]

We do a lot of big store parking lots and it is very common to have 2 or 3 levels of lighting.

1) Security lighting provides just enough light all over the lot and building to say it is lit.

2) Employee parking area - all lighting on in the designated employee parking area(s). This comes on early and stays on late for employees

3) All lighting and signage on ... self explanatory.

 

[sw_ross]

Thanks

Thanks

That's exactly the explanation I wanted to hear. I knew there had to be a logic behind this setup, and that make total sense.

Thank you.

 

[mgookin]

Was doing work at a business yesterday that I hadn't done work at before, so I wasn't totally up to speed on the buildings layout. In addition to some miscellaneous repairs they asked me to look at the outside light by the front door as it wasn't on when the head guy got to work that am.

Long story short, when I looked into how the outside lights were controlled I found a photo-eye and a timer-clock set up in series with each other to control a contactor. I'm trying to understand the design thoughts that would go into setting this up in that manner.

I can see the photo-eye and timer-clock being setup in parallel so that if you had a really dark day (stormy, cloudy, etc.) it would turn the lights on outside, or the timer-clock would turn the lights on at pre-set clock times (night-time).

I'm not sure I understand the benefits of setting them up in series. Can someone tell me what I'm not seeing?

Thanks, Sky

We do outdoor controls; that's all we do.

Series:
One Fortune 500 company we deal with is a retailer who is open from 10am - 9pm. All employees are gone by 9:45 so they use a photocontrol to let the lights come on in the evening and the timer to shut them off after employees are gone. And since they don't need am lighting, the timer is programmed to not let the lights come back on until afternoon. This is in series.

Parallel:
In parallel we have a customer who is a large, upscale resort development and they have a town center with theatre, restaurants, etc. They want to light up the town center outdoor lighting during the holidays, for special events, parades, etc. They used to send a guy up a ladder to walk across clay tile 3 stories up to put a cup over the photocontrol until we came along and showed them wiring options. With a photocontrol and timer in parallel, they can program those lights for the parade or holiday season.

What we make is a replacement for a photocontrol which functions the same but without the performance decay you get from a photocontrol. I only used the term photocontrol for easier understanding.

 

[James L]

We do outdoor controls; that's all we do.

Series:
One Fortune 500 company we deal with is a retailer who is open from 10am - 9pm. All employees are gone by 9:45 so they use a photocontrol to let the lights come on in the evening and the timer to shut them off after employees are gone. And since they don't need am lighting, the timer is programmed to not let the lights come back on until afternoon. This is in series.

That is the most common scenario in which I've used both in series. I might add:

Sunset varies so greatly from winter to summer that I usually will set the time clock (or timer) to turn on at 4:30 pm, then turn off an hour after the store closes. As in your scenario, maybe everyone's gone before 10:00. Without the time clock turning the lights off, the photo control would have them on all night.

If it's an office building or restaurant that's open for breakfast, a second set of time clock tabs tabs can be installed to turn on early in the morning, maybe 5:00 and then back off at 8:00 or so

The gist of it - regardless of how dark it is outside, the timer will not allow the lights come on until it's *typically* dark enough to need them. Then the photo control will not allow the lights to turn on until it's *actually* dark enough to need them. Then the timer turns the lights off after everyone is gone. Turning the parking lot lights and signage off after hours saves electricity and allows potential customers to know immediately that the store is not open

I've seen parking lot lights turn on at noon because it gets really cloudy, like in a thunderstorm, though it's not really dark enough outside to need them. Time control keeps this from happening

NOTE:
Power goes to the timer first, then the photo control. The clock needs to have power 24 Hours a day to run. You don't want the photo control turning the clock off

 

[mgookin]

...
...

NOTE:
Power goes to the timer first, then the photo control. The clock needs to have power 24 Hours a day to run. You don't want the photo control turning the clock off

Many timers use separate supplies for the clock and the lighting load. The clock may run on 120VAC and the load could be anything else. In this case the order does not matter as long as that photocontrol is only connected to the lighting load.

 

[ActionDave]

NOTE:
Power goes to the timer first, then the photo control. The clock needs to have power 24 Hours a day to run. You don't want the photo control turning the clock off

Maybe I want to make a parking lot lighting timer that will align itself with the solstice.

 

[kwired]

Maybe I want to make a parking lot lighting timer that will align itself with the solstice.

There are timers that can do that

 

[James L]

Many timers use separate supplies for the clock and the lighting load. The clock may run on 120VAC and the load could be anything else. In this case the order does not matter as long as that photocontrol is only connected to the lighting load.

Good point. thanks for bringing that up
I was thinking of that, too. But seeing the photo control on the load side of the clock either way

clearly, I should have clarified more clearly :thumbsup:

 

[kwired]

Good point. thanks for bringing that up
I was thinking of that, too. But seeing the photo control on the load side of the clock either way

clearly, I should have clarified more clearly :thumbsup:

May still depend on what is desired. If you had some lighting that needs to run all night as well as some that shuts off at a predetermined time, you may still have the photo cell ahead of a timer contact, or else you would need multiple photo cells.

 

[readydave8]

I had lites controlled by photocel and timer in series (photocel only had power when timer closed contacts), timers set to turn on before dark, so when they make contact, photcel turns lites on for a minute or so, then back off, then back on at dark (so I would call these photocels normally closed, lite makes them open).

So next time I'll put photcel before timer contacts.

 

[John120/240]

So next time I'll put photcel before timer contacts.

With the photo cell ahead of the timer; The lights come on at dusk & stay on until the timer runs out. Is that your intended operation ? What would be the application for such a setup ?

 

[GoldDigger]

Not that kind of timer and not ahead of the timer motor, just the load contacts of the timer.

Sent from my XT1080 using Tapatalk

 

[Little Bill]

I had lites controlled by photocel and timer in series (photocel only had power when timer closed contacts), timers set to turn on before dark, so when they make contact, photcel turns lites on for a minute or so, then back off, then back on at dark (so I would call these photocels normally closed, lite makes them open).

So next time I'll put photcel before timer contacts.

The reason your photocell came on for a minute or so and then went off is they (most) close for a minute or so when first powered up. Then depending on light conditions, they either turn back off (open) or remain on (closed).

 

[hurk27]

With the photo cell ahead of the timer; The lights come on at dusk & stay on until the timer runs out. Is that your intended operation ? What would be the application for such a setup ?

Most photo cells are a heater and bi-metal switch if you remove the power to the photo cell it will close the contacts and when the timer turns on during the day the lights will come on for 1 to 2 minutes until the heater heats up and opens the photo cell contacts, to avoid this problem when you use a photo cell in series with a timer you should always install the photo cell ahead of the timer contacts but not the timers clock motor, this way the photo cell always has power and you don't get this short cycle of the lights turning on when the timer comes on, this allows you to have the timer turn back on early so the photo cell can turn the lights on when it gets dark enough and you avoid having to always reset the time two times a year for winter and summer.

As stated many manufactures are making what they call astrometric timers that are set to the longitude of the location along with the daylight savings settings that can eliminate the need for photo cells altogether as they track the sunrise and sunset time through out the year, the one I use the most is the Intermatic EI600 series that goes into the place of a wall switch, I also use it to control contactors for larger systems, the reason is its so low cost (around $55.00) compared to other astrometric timers and has a 20 amp rating I just put a switch box below my contactor box, also it has a 3 volt lithium back up battery so you don't have to worry about power failures and having to reset the clock all the time, there were some hiccups with the first versions of them but the last few have been very reliable, also they have 40 set points as well as several holidays that can be set to different times.

 

[kwired]

I had lites controlled by photocel and timer in series (photocel only had power when timer closed contacts), timers set to turn on before dark, so when they make contact, photcel turns lites on for a minute or so, then back off, then back on at dark (so I would call these photocels normally closed, lite makes them open).

So next time I'll put photcel before timer contacts.

The reason your photocell came on for a minute or so and then went off is they (most) close for a minute or so when first powered up. Then depending on light conditions, they either turn back off (open) or remain on (closed).

They typically are a normally closed contact. The ones with relay coil operated contacts will flash the load very quickly when power is applied (only runs long enough for relay coil to pull in and open the output so it is usually very quick).Light on the photo sensor allows control circuit to allow current to flow to the relay coil.

They delay type have a bimetal operated contact and a heater that takes time to heat up to drive the bimetal to open. Absence of light on the photo sensor causes control circuit to open current for the heater, and the delay until the contact opens is the time it takes to cool the bimetal operator.


Let me add that you often find photo controllers that when they fail the output is in the constant "on" state. That is generally because the control circuit has failed and the contact remains in the normally closed state. When they fail to turn the load on at all the contact has likely failed in some way.

 

[mgookin]

Most photo cells are a heater and bi-metal switch if you remove the power to the photo cell it will close the contacts and when the timer turns on during the day the lights will come on for 1 to 2 minutes until the heater heats up and opens the photo cell contacts, to avoid this problem when you use a photo cell in series with a timer you should always install the photo cell ahead of the timer contacts but not the timers clock motor, this way the photo cell always has power and you don't get this short cycle of the lights turning on when the timer comes on, this allows you to have the timer turn back on early so the photo cell can turn the lights on when it gets dark enough and you avoid having to always reset the time two times a year for winter and summer.

As stated many manufactures are making what they call astrometric timers that are set to the longitude of the location along with the daylight savings settings that can eliminate the need for photo cells altogether as they track the sunrise and sunset time through out the year, the one I use the most is the Intermatic EI600 series that goes into the place of a wall switch, I also use it to control contactors for larger systems, the reason is its so low cost (around $55.00) compared to other astrometric timers and has a 20 amp rating I just put a switch box below my contactor box, also it has a 3 volt lithium back up battery so you don't have to worry about power failures and having to reset the clock all the time, there were some hiccups with the first versions of them but the last few have been very reliable, also they have 40 set points as well as several holidays that can be set to different times.

How long does it take to install and program that device?
And do you have to do all that again every time the battery dies?

 

[RICK NAPIER]

These system are required where the International Energy Code is adopted

C405.2.4 Exterior lighting controls.
Lighting not designated for dusk-to-dawn operation shall be controlled by either a combination of a photosensor and a time switch, or an astronomical time switch. Lighting designated for dusk-to-dawn operation shall be controlled by an astronomical time switch or photosensor. All time switches shall be capable of retaining programming and the time setting during loss of power for a period of at least 10 hours.