Here's the deal. There is a string of lights on poles in a community connected with URD (208 HID). They are on a dusk to dawn timer. The customer now wants 2 of them to go off at midnight and they don't want to dig up the place to add another conductor. Ideas?
Two come to mind with me.
An X-10 solution ... ugh. (lightning being the biggest issue)
A battery operated timer in the poles that go off at midnight but I don't find that timer suitable for HID. (plenty for 5-15 plugs)
That was the first thought but you would need an adjustable TD relay and it would be one more thing they would have to be messing with all the time.
I have some timers that use an electronic clock that will run years on a 9v battery but I can't find one that actually supports anything but a 5-15 and this probably needs to be in a 3R box. I guess if it is small enough it could be in the hand hole.
They have no interest in replacing a couple dozen brand new lights with LEDS. Putting everything on photo cells was considered but they would still have to buy 2 timers.
Digging again is not that tough but it is $1200 by the time they add the conductor.
I sent them off with the Paragon idea. $250 or so in parts. Lets see how that goes over. It says it can handle a 4 day power failure and the storage element is a big capacitor so it should charge up OK during the light on interval.
a Photocell could be placed at Fixture #2, which would perform _Dusk-To-Dawn_ control of the remaining Fixtures on the Circuit. The same Photocell may also control the second Fixture - performing the _On-At-Dusk_ function via the Photocell Load Side Circuit. This Circuit would be connected to the Fixture through a Time Clock's Dry Contacts. The Clock Circuit would be connected to the un-switched (Line) Side of the Branch Circuit. Time Schedule would be A: "ON" at 16:00:00 AST / ADT, B: "OFF" at 23:59:59 AST / ADT.
The first Fixture would have both a Photocell and a Time Clock, however the Photocell on this Fixture will _NOT_ control downstream loads (only the first Fixture).
A slightly more detailed version of this Control Scheme would incorporate a 2 Pole Electrically Held Contactor at the 2nd Fixture, with the Contactor's Coil being driven (Controlled) by the Photocell.
This method also eliminates the _"Live Screwshell"_, or "_Shocking Experience_" often found with Lamps being connected across 2 Pole Circuitry. As compared to simply controlling one of the Two Ungrounded Conductors via a common Photocell, the Contactor would open both Ungrounded Conductors of the 208V 1 Phase 2 Wire Branch Circuit.
Use NEMA 3R Enclosures for the Time Clock(s) and Contactor(s). Mount a Stem-Type Photocell to the exterior of the Enclosure(s), with a clear aim at Geographic North.
On a somewhat related note, I am curious if daily outages may cause operational issues with Electronic Time Clocks. This is in response to the option of running the Timers in Battery Backup mode during Daylight Hours... i.e.:
"I have found some regular timers with electronic clocks that say they can hold the clock for up to 96 hours in a power failure. That might do the trick. Something like a Paragon EC7000 in double pole."
An advanced technique would involve Carrier Current Controls (like X10 Devices), setup in much the same way as the technique described above. Drawbacks will be the Lightning Surges that frequent the State of Florida.
The best option overall may be to have the Landscapers provide some Trenching for you between certain Poles, and you (or your Crew) Install some PVC + several #10 CU Conductors.
*** CYA NOTICE *** Notice the Qualifying Text "Have The Landscapers Provide Trenching For You" This should eliminate / reduce the Back-Charge Issues + Nastygram submissions oriented around the repair / replacement of Plants, Grass and Groundcover.
Scott " 35 " Thompson Just Say NO To Green Eggs And Ham!