Author Topic: A not clear phenomenon that accurs in the US road lights  (Read 2072 times)
dor123
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A not clear phenomenon that accurs in the US road lights « on: March 12, 2010, 09:38:04 AM » Author: dor123
There is a phenomenon, that is not clear to me, in fact that all US made street lights contain a PC sockets. This is not the case of any street lights made outside the US (Europe for example). I don't know why operating automatically a street light or yard light independently is so common in the US, while in another locations in the world (Like in Europe) there aren't any traces of this (Like in Israel were all of the streetlights in every neighborhood or random group outside neighborhood in cities operating by a shared automatic switch [Usually time]). These road and yard fixtures with photocell socket and also the photocells they uses are all unique to the US lighting industry.
« Last Edit: March 12, 2010, 09:54:14 AM by dor123 » Logged

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Re: A not clear phenomenon that accurs in the US road lights « Reply #1 on: March 12, 2010, 02:34:14 PM » Author: Medved
Historical and urbanisation density reasons:
When public lighting appear to Europe, it was operated by public companies, that mostly build separate power grid for them. It start with gas, the same concept used later for electrical lighting. Even for gas lanterns, the effort was made to minimize the labor necessary to control them, so centralized control systems were used (pressure wave ignition,...). And again, for electrical lighting the same concept was reused. The public lighting (mainly carbon arc) used separate power stations, with each group of lights having separate dynamo (acting at the same time as necessary ballast), while the lighting was controlled by running or not running the power generating station.
So since then public lighting has separate low voltage (230V) distribution lines, what are powered only when lights are necessary. Some eras the advantage of centralized lighting control was used even as power grid load stabilizing control element: When there was severe excess of energy production, lights were turned ON. Installed systems still allow it, but i'm not aware of any case lighting being used for grid load stabilization in latest at least 15 years.
Today this group control wiring is used for group dimming: One common dimmer box reduce the voltage for large group of lights (for HPS), so individual lights suffice with simple ballast choke and ignitor, they do not need separate dimming auxiliaries.

In US Thomas Edison spread the use of electricity to homes as first, so permanently powered power lines were laid everywhere. Ten later on, the electrical lighting start to spread. But nobody want to invest for new power network for lights, so they were hooked to existing, permanently powered power lines, what called for some switches to control each lantern and for some degree of their automation. And the lowest maintenance automated control system are light controlled switches: They were simple, not as much expensive (early days, today they are really cheap) and need no periodic readjusting (like timer switches - a bit cheaper competitive system in the era of nearly century ago). So since then, in US (and consequently in UK as well) are mostly used individually controlled lights.
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icefoglights
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Re: A not clear phenomenon that accurs in the US road lights « Reply #2 on: March 12, 2010, 09:16:20 PM » Author: icefoglights
It depends somewhat on the area and how the community pays for the streetlights as well.  In some areas, the community pays a flat fee for the installation of each street light, owned and serviced by the power company.  These lights are than connected to the nearest convenient power source, usually the transformer that services nearby houses or other customers.  The next light down the street maybe powered off a different transformer, so each needs its own photocell.
In the area I live, that model doesn't work so well.  With extreme seasonal variation, street lights may only be on a couple hours each night in the summer, and nearly 2/3rds of a day in the winter.  Here, street lights are owned and operated by the city/state government and centrally controlled with their own wiring, as each string also needs to be metered.  It would be more expensive to have each light independent of each other as it would mean each light would also need a meter.  In this case, a string of several lights has a controller, with single transformer, meter, photocell and relay controlling several lights.
Some street lights here have built in photocell sockets with shorting caps in place, but the majority were ordered without the photocell sockets.  My M250 Crimefigher was made without the photocell socket.
« Last Edit: March 13, 2010, 12:33:04 AM by icefoglights » Logged

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Re: A not clear phenomenon that accurs in the US road lights « Reply #3 on: March 14, 2010, 11:03:51 PM » Author: arcblue
This is very true - my area operates as a "lighting utility district (LUD)" where I pay for my neighborhood's streetlighting as a separate flat-fee charge on my bill. Streetlights owned by the county (rural roads, suburbs and most town & city roads) are typically wired as icefoglights mentions - to whatever local transformer is convenient - and thus are individually switched. Downtown areas of cities and State-owned (department of transportation) streetlights on highways and their intersections & on-ramps are usually group-switched. Sometimes the groups are quite large, stretching for blocks to even miles. These patterns seem to be the norm in many areas of the United States.

One must also remember that back in the incandescent days, high-voltage series circuits were most common, and a photocontrol or timer would control the power to the constant-current regulator (fed by high-voltage lines of many kilovolts) to a large group of lights. Many of these circuits remained throughout the mercury vapor days & some still exist today, particularly in California - some of these series were quite large. It's amazing watching every incandescent light as far as the eye can see, all come on at once.
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Re: A not clear phenomenon that accurs in the US road lights « Reply #4 on: March 14, 2010, 11:25:10 PM » Author: joseph_125
The same thing is also true in my area, most of the streetlights on smaller streets and on most roads owned by the county are utility owned and are also wired to the same way that icefoglights mentions-to the local transformer and thus are individually switched. Most suburban residential areas here also follow this wiring scheme but some use underground wiring and pad mounted transfomrers. I've only seen a few suburban residential installations with group switching using a pole mounted relay.

The streetlights for highways which are owned by the province(Ministry of Transport)are always group switched by a large photo controlled relay cabinet mounted at each interchange for freeways, The relays inside controls the lights on that section of freeway to the next interchange. For the other highways, pole mounted relay boxes are used near the streetlights.
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Re: A not clear phenomenon that accurs in the US road lights « Reply #5 on: June 22, 2010, 08:33:56 PM » Author: streetlight98
Yes, the lights on utility poles in my area run off transformers, which requires a PC. THe ones on the freeways are not, because relays are a cheaper option.
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