Discuss Has anyone seen 3 phase lighting in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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star or delta ?
The O / P was referring to star wasn't he ?
So where is the error ?

In a three phase star,
the current in the neutral could be,
as high as 1.7 times the individual phase currents.

it is NOT ever 3 times
(not at any one time).

The OP was referring to 3 circuits, all connected to the same phase, sharing a neutral.
 
Also, where does the 1.7 come from? If the load is resistive (or phase angles are all the same) then the Neutral current should never be more than the highest phase current. I know harmonics etc can increase neutral current but didn't know 1.7 was a rule for this?
 
See for the lights to work with a 3 phase breaker and one neutral could you have 3 switches or just one switch to a contactor ? My thinking 3 separate switches potentially the neutral carrying a return voltage if you work on other lights
 
See for the lights to work with a 3 phase breaker and one neutral could you have 3 switches or just one switch to a contactor ? My thinking 3 separate switches potentially the neutral carrying a return voltage if you work on other lights

I was thinking that but with a single pole switch the neutral would not be broken so would remain at neutral potential. And you should really be fully isolating the circuit to work on it which would be done either via a linked 3ph MCB or maybe a 3/4 pole isolator next to the switches. Not sure if regs permit this though.
 
If you intend to wire a large area with lighting split over a 3 phase supply, then you would surely, wire the lighting utilizing 3 SP supplies L and N, trying to avoid the Stroboscopic effect especially if you are using fluorescent lighting, something a competent Electrician should be aware of, just saying. Where does the confusion lye?
 
It’s not me that’s wiring this someone is wanting to wire like this. 3 phase breaker 1 neutral and have the different phases to switch 3 sections of lights. That’s what they want to do, doesn’t sound ok to me
 
It’s not me that’s wiring this someone is wanting to wire like this. 3 phase breaker 1 neutral and have the different phases to switch 3 sections of lights. That’s what they want to do, doesn’t sound ok to me
What you describe there is fine.
Just to be clear though, it has to be 3 different phases.
 
3 Phase lights - Yes
and Lighting over 3 phases - Yes
As far as I am aware, there are no 3 phase light fittings.
3 phase lighting is either wired as 3 separate single phase circuits with a line and neutral conductor for each phase, or as as 3 phase circuit with the phases supplying alternate fittings and a single neutral conductor supplying all the fittings.
With the second option the neutral conductor is usually the same size as the phase conductors.
Some situations (such as street lighting) use a 5 core cable which is daisy chained to each fitting.
Other situations use a track system with clip on fittings, each fitting designed to only connect between a single phase and the neutral.
 
See for the lights to work with a 3 phase breaker and one neutral could you have 3 switches or just one switch to a contactor ? My thinking 3 separate switches potentially the neutral carrying a return voltage if you work on other lights

If the lighting is fed from a three phase mcb then a switch and contactor to control the lights would be the better option in my opinion. If you want each phase on a separate switch then three seperate circuits would be the way to go in my opinion.
 
As far as I am aware, there are no 3 phase light fittings.

I disagree, a while back we were researching flood lights for a particular job and a colleague discovered some 3 phase flood lights.
Not those particular ones but I found this online this morning (Spec'n below).

Has anyone seen 3 phase lighting upload_2019-3-24_10-25-9 - EletriciansForums.net
 
See for the lights to work with a 3 phase breaker and one neutral could you have 3 switches or just one switch to a contactor ? My thinking 3 separate switches potentially the neutral carrying a return voltage if you work on other lights
So, use 3 SP breakers from 3 Phases instead of a TP.
3 DP switches with individual outgoing neutrals to 3 light circuits.
 

Reply to Has anyone seen 3 phase lighting in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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