# lighting, contactors , time clock and photo cell.



## green light (Oct 12, 2011)

tommiedon said:


> Hello everyone , I have a question regarding a lighting circuit which goes through the contactor, which is then controlled by a time clock and has also got a photocell. I have 3 lighting feeds and one 3 core to the photocell, the time clock is to be over rided by the photocell. all your help would be great. thank you.


 First, are you an electrician, and what is your question?:blink:


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## kbsparky (Sep 20, 2007)

tommiedon said:


> Hello everyone , I have a question regarding a lighting circuit which goes through the contactor, which is then controlled by a time clock and has also got a photocell. I have 3 lighting feeds and one 3 core to the photocell, the time clock is to be over rided by the photocell. all your help would be great. thank you.



What is a "3-core"? A 3-conductor cable? Are you working with 120 Volts here?


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## John Valdes (May 17, 2007)

Whats the question as this set up is common?


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## tommiedon (Oct 6, 2012)

yes I am an electrician , and secondly it's just the first time I have done it. 3 core and earth. so I have 3 feeds to 3 different lighting circuits, then one 3 core and earth to the photocell. I am just a bit stumped on the connections , I understand from the breaker to the top of the contactor it's just the rest, sorry for sounding thick, it's just the first time I have done it.


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## tommiedon (Oct 6, 2012)




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## Vintage Sounds (Oct 23, 2009)

Pass the lighting circuits through the contactor. Use the same control power circuit for the time clock and the photocell. Set up a NO/NC ice cube relay so that the output of the time clock passes through the relay's NC contact, going to contactor coil. Unswitched control power should be on the NO relay contact, also going to contactor coil. Last the photocell output should be connected to the relay's coil. So when the photocell turns on, it disconnects the time clock output and energises the lighting contactor. When the photocell is off, only the time clock can apply power to the contactor.

Maybe you could even do it without the relay(just putting time clock and photocell in parallel) but that depends on whether the time clock likes to be backfed or not.


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## John Valdes (May 17, 2007)

Here is the schematic for your application, minus the power connections that you say you already know.

_PS......Courtesy of EZ Schematics 
_


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## Surge03 (Sep 23, 2012)

tommiedon said:


> Hello everyone , I have a question regarding a lighting circuit which goes through the contactor, which is then controlled by a time clock and has also got a photocell. I have 3 lighting feeds and one 3 core to the photocell, the time clock is to be over rided by the photocell. all your help would be great. thank you.


Guys parallel photocells with time clocks because of daylight savings changes so much.If you get rid of the photo cell it will make it less confusing for you.Now you just have NO/NC to your coil single pole single throw


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## 220/221 (Sep 25, 2007)

I use this system all the time so where the off time is to be before dawn. It avoids resetting the on time to keep up with dusk.

Just run the switch leg from the photo cell thru the contacts in the timer. Set the timer to come on a 4PM and off whenever desired. Timer contacts will close well before dusk and await the power from the PC. Obviously the timer motor always has to be energized and there are different methods of accomplishing that.


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## Magnettica (Jan 23, 2007)

With your control circuit, feed the time clock first, then the photo eye. The photo eye load side (usually the red leg) supplies voltage to your contactor coil. Like 220/ 221 said, the time clock control power to the photo eye and the photo eye controls the contractor.


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## Aussielec (Apr 1, 2012)

kbsparky said:


> What is a "3-core"? A 3-conductor cable? Are you working with 120 Volts here?


Pretty much, thats how we describe how many conductors a cable will have over in Europe and Aus. So a three core cable with a flat or circular sheath will have 3 conductors plus earth. 

We generally don't classify the earth as a core because it carries no current under normal conditions and thus does not contribute to derating factors in the cable.

@Tom, put the photocell and the timeclock contacts in parallel. Then out to your contactor coil. Johns pictures is what you need.


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## John Valdes (May 17, 2007)

Magnettica said:


> With your control circuit, feed the time clock first, then the photo eye. The photo eye load side (usually the red leg) supplies voltage to your contactor coil. Like 220/ 221 said, the time clock control power to the photo eye and the photo eye controls the contractor.


Connecting both photo-eye contact and timer contact in parallel will allow either device to over ride the other. They can both be closed for that matter.
It simple enough. Day Light saving time in effect or not, the circuit posted will make the lights come on when the sun goes down. No matter what.


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## Vintage Sounds (Oct 23, 2009)

The photocell and mechanical timer setup is pretty common because it's reliable and does its job but I think in this day and age a nice astronomic timer is a better option. The good ones have supercapacitor or NVRAM backup and don't depend on batteries to remember the settings in event of power failure. They self-adjust for sunrise/sunset changes throughout the year which makes having a photocell redundant and they also don't need to be oriented facing north. I like to set them to turn on 10 minutes after "sunset" because it's not really quite "dark" then. A single circuit Tork EWZ101 is only $150 or something.


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## kbsparky (Sep 20, 2007)

Aussielec said:


> Pretty much, thats how we describe how many conductors a cable will have over in Europe and Aus. So a three core cable with a flat or circular sheath will have 3 conductors plus earth.
> 
> We generally don't classify the earth as a core because it carries no current under normal conditions and thus does not contribute to derating factors in the cable...


I seem to remember seeing a cable labeled 3/036. It had 2 circuit conductors, plus a bare earth conductor. 3 strands per conductor, 036 diameter per strand? Do you use that anymore?

Similar to what we call type NM sheathed cable in North America....


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## chicken steve (Mar 22, 2011)

John Valdes said:


> Here is the schematic for your application, minus the power connections that you say you already know.
> 
> _PS......Courtesy of EZ Schematics _


is the obvious , that this can be an exclusive 120V circuit managing a 480 3ph one be part of the confusion here?

~CS~


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## Aussielec (Apr 1, 2012)

kbsparky said:


> I seem to remember seeing a cable labeled 3/036. It had 2 circuit conductors, plus a bare earth conductor. 3 strands per conductor, 036 diameter per strand? Do you use that anymore?


Geeze the old three stranded cable was done away with along time ago here in Aus...( 3 means the number of strands and 0.36 means the diametre of each strand in millimetres)

Now-a-days we have 2.5mm2 (7/0.67) and 1.5mm2 (7/0.5). You will only ever encounter cables with three strands in pre 1990 houses. The bare earthing conductor has also been done away with, all earthing conductors now must be insulated.

What is NM sheathed cable?


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## chicken steve (Mar 22, 2011)

this is NM....

~CS~


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## John Valdes (May 17, 2007)

chicken steve said:


> is the obvious , that this can be an exclusive 120V circuit managing a 480 3ph one be part of the confusion here?
> 
> ~CS~


 You are most likely right.


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## Shockdoc (Mar 4, 2010)

Often the photocell is used to turn the lights on , the timeclock is used to turn them off shortly after closing time. If that is the case you should find the clock motor fed independantly of the contacts in the timeswitch. from the timeclock the contactor is fed to throw your lighting circuits on and off.


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## stlchuck (Jan 9, 2009)

If both a time switch and photocontrol are used, they should be wired in series with each other, not in parallel. If they are in parallel, the pec will turn lights on and off as it gets light and dark,but the timer won't be able to override the pec and turn lights off when it's still dark, so all the timer would be able to do is keep the lights on when it is daylight and the lights aren't needed.
Shockdoc is correct about feeding the clock motor independent of the timer contacts,but you should also make sure the pec is ahead of the time switch contacts if you're using a standard line voltage pec. Otherwise if the time switch contacts close, energizing the pec, the pec will be in the closed position, (it's normal state when no line voltage is applied),and will turn the lights on even if it is daylight out, for however long it's time delay is, which will reduce lamp life due to unnecessary starts and waste power.


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## Surge03 (Sep 23, 2012)

stlchuck said:


> If both a time switch and photocontrol are used, they should be wired in series with each other, not in parallel. If they are in parallel, the pec will turn lights on and off as it gets light and dark,but the timer won't be able to override the pec and turn lights off when it's still dark, so all the timer would be able to do is keep the lights on when it is daylight and the lights aren't needed.
> Shockdoc is correct about feeding the clock motor independent of the timer contacts,but you should also make sure the pec is ahead of the time switch contacts if you're using a standard line voltage pec. Otherwise if the time switch contacts close, energizing the pec, the pec will be in the closed position, (it's normal state when no line voltage is applied),and will turn the lights on even if it is daylight out, for however long it's time delay is, which will reduce lamp life due to unnecessary starts and waste power.


Yes in series but if you drew your circuit that you are talking about its in parallel,unless I'm missing something here.The whole point is for this set up is that it reduces the time that we have to change the time on the clock especially if you have a lot of these to change.People here complain lights being on even for 5 minutes if the sun is up.I do this set up so when I do have time to change it I don't have a lot of complainers.


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