Why You Need Neutral Wire For Low Voltage System

You might or you might not wondering..why there are neutral wire in our Low Voltage (LV) System!

Unlike LV System, High Voltage (HV) System only requires 3 wires (red, yellow & blue) which neutral wire are not required.

The main reason is to "Balance" those currents. Maybe some of you do understand what does I mentioning about...and some of you are totally having no idea at all.

Currents is in a "Balance" condition in HV System but vise versa in LV System. theoritically, currents in HV System are derived as Ir = Iy = Ib.

However in LV System, those currents derives as per Ir + Iy + Ib = 0.

The above formulas clearly shows that in HV, all currents are the same while in LV, those currents are not the same...so then the neutral wire i needed to balance those 3 currents.

Still don't get what I mean!.....okay, consider the below scenario.
Let assume Mr. A, Mr. B and Mr. C living in a terrace house and their houses are next to each other in a same row.

The source of power are comes from nearby substation (which the incoming power supply is HV and step down to LV) and connected to those houses. Since the power demand for each houses are not the same, the current usage will be difference as well. Remember, the substation are giving the same amount of current for every phases. Therefore, the neutral wire are needed in order to "balance" the amount of current at every phases.