Lighting Layout Plan 1

[ryan356]

Hi everyone. This is my first post here. I am currently in the process of designing a shopping plaza. We are most of the way there and we are to the point of figuring out the electrical plan for lights. I have talked to our electrical consultant about the way to go, an electrical engineer at Cutler-Hammer and others in the electrical field with different answers. Now I come here for another opinion. I am not sure which way to go with the wiring for the 50 something lights we have (67 fixtures in all-1000W each). Our inspector has talked to some electricians at Walmart and they use single phase with underground sub-panels to split the lights into zones like I had originally planned. I figured this would save on wiring costs b/c you would only have to run a large guage wire to the subpanels and then out to the lights with smaller guage runs. The Cutler-Hammer engineer burst my bubble when he told me that he thought the 3 phase with long runs would be the way to go. Which, I would think would be way more expensive because of the long, large wires being run. (The longest run is almost 1000 feet!) So now I have two fairly good sources with differing views. Sounds to me like preference is coming into play here. So what have you guys (gals) seen? Any help is appreciated. Thanks.

Ryan

 

[mpparent]

I'm assuming you are talking about an outdoor lighting scenario. W/ 1000W fix's, I would run 3 phase (hopefully, you have 480V if you are in the US). Just make sure that you are using poles 22' or better per NEC req's.

Mike

 

[arnsam]

To simplify the problem, if you can get these fittings in 3-phase that will reduce the cost of your cables, meanwhile it will be easily to balance the total load, OTHER items such as distribution board will not differ mnuch with cost.

FOR 3-PHASE LIGHTING FITTING, 1 Fitting of 1000W @ P.F = 0.8, 400V 50Hz, the total current drawn = 1.8A, According to IEEE wiring regulations (OUTdoor installation) the total load for lighting circuit must not exceed 32A/Sqrt2 = 22.6A. Hence in each circuit you will have 22.6/1.8 = 12 Fittings wired with 4.0mm sq cable at < 40Centgrade (room temperature) in PVC conduit. For 67 Fittings, you will need 67/12 = 6 three circuits. ((NOTE: OBSERVE THE VOLTAGE DROP AT LONG DISTANCE & CURRENTS DRAWN BY CONTROL GEARS, AND OTHER SPECS PROVIDED)



FOR 1-PHASE LIGHTING FITTING, 1 Fitting of 1000W @ P.F = 0.8, 230V 50Hz, the total current drawn = 5.4A, the total load for lighting circuit must not exceed 32A/Sqrt2 = 22.6A. Hence in each circuit you will have 22.6/5.4 = 4 Fittings wired with 4.0mm sq cable at < 40Centgrade (room temperature) in PVC conduit. For 67 Fittings, you will need 67/4 = 17 single circuits (NOTE: OBSERVE THE VOLTAGE DROP AT LONG DISTANCE & CURRENTS DRAWN BY CONTROL GEARS, AND OTHER SPECS PROVIDED)

In both alternative, 1No. Three Phase distribution board of 6 or 8 ways to allow for spares with the incomer 200A 3P MCCB is sufficient.