highway lights

[shadow]

Hi guys I need help with lights. I have 480/277 load center 3 phase I have 40 lights comming out of load center . In panel i have 4 3 phase breakers . lights are controled by photo cell which activates 4 contactors to turn lights on . My problem is one of the legs , the C leg has no power , i opend the handholes at each pole and checkd for power and found none ,also checkd wireand insulation to see if it was O/K no triped breakers. Any thing i missed need help THANKS.

 

[jimwalker]

Re: highway lights

need bit more info.
1 are the contactors open or closed
2 what leg is the photo cell on
3 what are the readings on both sides of contactors
if the photocell is off C then nothing would work

[ June 07, 2004, 06:07 PM: Message edited by: jimwalker ]

 

[shadow]

Re: highway lights

photo cell kicks in the contacs also theirs a bypass switch and a time clock on 120 volt whe n turned on i only have power on 2 legs A B no C

 

[ed downey]

Re: highway lights

Are These Lights Really 3 Phase? I Have Seen Panels That Have 3 Pole Circuit Breakers In Them That Are Only Using A & B Phase Since The Light Poles Are 480V 1 Phase.
-Ed

 

[shadow]

Re: highway lights

Lights are 277 volt checked all hot legs at panel and i have 277 volts from ground to each leg also at the load side of contactor i have 277 volts still have no power on C leg at poles. Will mixing some of the legs cause the C leg to have no power. I have 12 wires on 4 contactors 3 on each phase . P S i checked all connections and they seem to be O K . I,m at a loss here need help . Thanks.

 

[luke warmwater]

Re: highway lights

Originally posted by shadow:
Will mixing some of the legs cause the C leg to have no power. Thanks.

If all 4 breakers are on and you have 277 to Neutral on the load side of all 4 contactors, then probably not.
Say you have (2)- A phases and one B phase. You would read zero between A and A. But both A's to neutral would still give you a reading.
I think that you probably have a broken wire or possible bad splice somewhere.

 

[hurk27]

Re: highway lights

Shadow How many lights are on each pole? I have never seen a 3-phase fixture so I'm betting if you can find which two legs run up the pole to each fixture you might be able to temporally jump the fixtures that are tied to "C" phase to one of the other phases to get them back up and running. but watch the load as you don't want to over load the circuit. Most roadway installs I've seen are over sized on the circuits anyway and will take the extra load if evenly split across the remaining two leg's. at least until you can get another feed ran. most roadway lighting will balance the fixtures evenly across all three phases so you will have to alternate every other one between "A" and "B" phases. this will have to be done at each pole that uses the "C" phase.

 

[jimwalker]

Re: highway lights

Something is open.When doing service work we need to remember that it DID WORK before