Lighting

WHAT VOLTAGE?

You need to give a lot more information. Voltage being paramount, how many light fittings, final connections via sub distribution fuses?

What is the voltage?

What type of lighting?

Total load of various lights are 50kW or is it single load?

What is the distance between Distribution board and Lights?

Type of installation whether it is indoor or outdoor, climatic conditions, explosion/flame proof applicable area..etc??/

Voltage avialable is 415v and 240V. Lighting is inclusive of plant areas, office building, street lights, 50 KW is the total lighting load having both indoor, outdoor, flameproof, corrosive climate. Distance between board and light varying from 50 - 300 mtrs

Well, Do you want to know the cable size from Distribution boards to lights for each circuits?..Provide load and distance of each circuits.

Load is 10 KW and distance is 175 mtrs

Is it 10kW only. It was 50kW,as you said before. or is it 5 circuits of 10kW.??.. how did you do phase balancing?

Do you know the formulae of power calculation in 3 phase and single phase? Do you know how to calculate the current carrying capacity of conductor?

This has gone beyond "what size cable" it's now in the realms of system design. I don't think anyone on this board would be prepared to attempt to answer your question.

I'm afraid everyone here has missed the point.

You must use the cables that are specified by your local building codes. Here in the US the default standard is the NFPA 70 National Electrical Code. You should have this work done by somebody who is licensed to do this work. The 21 hour class I took to get my certificate taught me how to read the cryptic book that contains these codes. There are many parameters one must consider in choosing the wire gauge, insulation material, mounting, environmental concerns etc. I do not know what the Indian building code standards are called but being a former British colony I'm certain that there is a complete bureaucracy with a codified set of standards that handles this.

Dear OP, You didnt answer my query at #8. May be you could have done it yourself by the time!!!

...........or maybe British Standard 7671 could be wheeled out again so as to save the CR4 reader from "death by 20 questions".