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#24435 - 04/12/03 08:51 AM Timeclock and photocell  
drillman  Offline
Member
Joined: Mar 2003
Posts: 97
Somewhere in Texas
I need to put some lights up outside.
Parking lot style pole lights, but mounted on an I beam. There are 12 - 400 watt metal halide.

Boss wants to turn them on with a photo cell but turn them off with a time clock as they MUST turn off no later than midnight.

I figure putting a photocell and a timeclock in series with a lighting contactor coil will do the trick. I will set the timeclock to turn on at 4 pm.

Boss does not want an astromical time clock for whatever reason.

Does anyone have any experince with this?
It sounds like a good idea to me, just wanted to run it by you guys before spending to much time and money on it.


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#24436 - 04/12/03 09:17 AM Re: Timeclock and photocell  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
The way you describe is not unusual and it will be cheaper than an astronomical clock.

On the Energy Management systems we work on it is on by photo sensor off by time.

Quote
a photocell and a timeclock in series with a lighting contactor coil


Clock first right? [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#24437 - 04/12/03 09:19 AM Re: Timeclock and photocell  
jbfan  Offline
Member
Joined: Feb 2003
Posts: 69
Newnan, GA
What voltage? you should be able to get a simple time clock with 1 on and 1 off pin, set that in series with the photo cell and back to the contactor. That is the set up we use where I work. Each light we have has its own photo cell, but will work with a single one. the simple time clock is a 24 hour clock and should run about 60 bucks


"Yes I am a Pirate, 200 years to late" Jimmy Buffett

#24438 - 04/12/03 10:25 AM Re: Timeclock and photocell  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,259
Fullerton, CA USA
We set them up as follows:
The photocell is constantly powered on the line side. The load side of the photocell is connected to
1. Contactor(s) coil(s) that run dusk to dawn lighting (selected fixtures for security lighting)
2. The line terminal of the time clock. (Clock motor is connected to same constant power as the P/C)

The load side of the time clock runs to contactor(s) for fixtures that are meant to shut off at a specified time.

Operation Scenario:
All lights come on with P/C simultaneously (T/C set at 3PM). The selected loads shut off with the T/C, usually 1/2 hr or so after the closing of stores, mall, etc.
The remaining security lighting stays on until the morning, via the P/C.
This eliminates any need for an astro clock.

We avoid the use of electronic T/Cs whenever possible, because the customers don't understand the programming, and call us back when they get in trouble by trying to change something. It's much easier to give them a mechanical clock (T101) with a dial they can understand...S


#24439 - 04/12/03 04:44 PM Re: Timeclock and photocell  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,211
SI,New Zealand
This may sound stupid,
but, what is an Astronomical Clock?.
Never heard of one of these before. [Linked Image]


Let's face it, these days if you're not young, you're old - Red Green grin

#24440 - 04/12/03 04:46 PM Re: Timeclock and photocell  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
drillman — Fisher-Pierce controls are avaialbe through most elelctrcal wholesale outfits. http://www.fisherpierce.com/N281.htm “automatically turns off the luminaire at a preset number of hours after sunset” http://www.fisherpierce.com/NS476.htm “Three pole locking-type receptacle with polypropylene housing and 1/2" pipe thread”

I’ve found out the hard way that if you use a timer switching a photocell, the cell won’t last very long. As electure implies, the photocell needs to be powered continuously, with its output switched by the timer contacts. Obviously, the timer motor has to be continuously powered too {unless you really hate your boss.}

If you don’t use a contactor, you are limited to three 400W fixtures on each photocell. A limitation of using individual controls for groups of lights is that they will not all turn on/off at the same time. A contactor fed by one cell is needed to assure that. Contactor sizing is based on operating voltage and fixture-label current rating. A properly sized magnetic starter with its overload block removed will work for this.




[This message has been edited by Bjarney (edited 04-12-2003).]


#24441 - 04/12/03 07:08 PM Re: Timeclock and photocell  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Trumpy, an astronomical clock is a time clock which compensates for the changing sunset time.

The older ones where all mechanical and expensive, now I have seen electronic versions that cost less, but I find a lot of the electronic clocks to be prone to failure.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#24442 - 04/12/03 07:45 PM Re: Timeclock and photocell  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
I have not had trouble when swithcing the photo cell as would be the case if you are using a time clock on site lights that have intergal photocells. But electures description of wiring the clock and photocell in paralell is a nice way to go if you can.

IMO photocells are killed by overloading most times.

As for contactors, motor contactors are limted to 3 poles, we usally use lighting contactors as these can come with many poles so you can contol all of the sites lighting thru one contactor, or we might use a contactor panel if there is a lot of circuits to control.


[This message has been edited by iwire (edited 04-12-2003).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#24443 - 04/12/03 11:36 PM Re: Timeclock and photocell  
ThinkGood  Offline
Member
Joined: Aug 2002
Posts: 1,081
Milwaukee, WI
Man, Bjarney, for a second I thought you had linked to http://www.fisherprice.com


#24444 - 04/13/03 12:06 AM Re: Timeclock and photocell  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
Face it TG -- Walt Disney owns everything.


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