Three phase supply & wiring to street lighting

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eb49

eb49

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Hi:bye:! in regards to the Title mentioned above & to the inserted picture, I have a question for 3 phase wiring for multiple Street Lights. (As per my own analysis the circuit can be considered as multiple circuits installed in a single conduit.) The system is Line to Line 220V,3 Phase+Ground
My question is the ff:
1. The effect of unbalanced currents to voltage drop? :?
2. Induced heating to nearby wires, due to the effect of unbalanced currents? :?
3. Is this arrangement or wiring be code compliant? :?
4. Or any suggestions to improved this type of wiring diagram? :?



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Welcome to the forum. Your diagram is how I would wire the lights. As long as the wires are in the same conduit, and the loads relatively balanced*, inductive heating is not an issue.

*If for example you have 50 220V 250W street lights, 17 would be wired to AB phase, 17 to AC phase, and 16 to BC phase. The imbalance is only 250W, a little over an amp at 220V.
 
JFletcher said:
Welcome to the forum. Your diagram is how I would wire the lights. As long as the wires are in the same conduit, and the loads relatively balanced*, inductive heating is not an issue.

*If for example you have 50 220V 250W street lights, 17 would be wired to AB phase, 17 to AC phase, and 16 to BC phase. The imbalance is only 250W, a little over an amp at 220V.
Click to expand...

Even though the load on the three phases may be unbalanced, the vector sum of the currents in the three lines must still always be zero at every point along the circuit as long as all three hot wires are present. There will be no inductive heating regardless of the balance.
 
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1. The effect of unbalanced currents to voltage drop? :? Yes, it will have a small effect, but as mentioned earlier, keep the lights balanced by alternating phases for each light, and the unbalance should be fairly small.
2. Induced heating to nearby wires, due to the effect of unbalanced currents? :? The unbalanced current will be small, so nothing to worry about. Besides, wires are usually upsized so much for voltage drop, you don't have to worry about induced currents. You do need to worry about conduit fill and derating for more than 3 conductors in a conduit, but again, the wires are usually upsized enough for VD to take care of this.
3. Is this arrangement or wiring be code compliant? :? Yes, as long as the breaker is a 3 pole breaker.
4. Or any suggestions to improved this type of wiring diagram? :? I think that diagram is the most efficient way to do it at least in terms of smallest voltage drop. Using 2 pole breakers and 2 wire circuits is probably easier to design, and may make service easier.



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eb49 said:
View attachment 2387158
Hi:bye:! in regards to the Title mentioned above & to the inserted picture, I have a question for 3 phase wiring for multiple Street Lights. (As per my own analysis the circuit can be considered as multiple circuits installed in a single conduit.) The system is Line to Line 220V,3 Phase+Ground
My question is the ff:
1. The effect of unbalanced currents to voltage drop? :?
2. Induced heating to nearby wires, due to the effect of unbalanced currents? :?


3. Is this arrangement or wiring be code compliant? :?

4. Or any suggestions to improved this type of wiring diagram? :?
Click to expand...
hello there!,
can I see your computation on Voltage drop on this? i have the same situation here and need to know how voltage drop will be computed. hope you can help me. thanks in advance.
 
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