Why neutral cable size is half of phase cable?

The neutral wire, often seen as the unsung hero of the electrical world, is indeed half the size of the phase cable. Why, you ask? It's all about balance.

In a perfectly balanced system (which, let's face it, is as rare as a unicorn sighting), the neutral wire carries no current. But in the real world, where unicorns are as mythical as a perfectly balanced electrical system, the neutral wire does carry some current due to the imbalance between the phases. This imbalance is the reason the neutral wire is allowed to be smaller.

Think of it like a seesaw. If you have two perfectly equal weights on either side, the seesaw stays level, and the fulcrum (the neutral wire in our electrical analogy) doesn't move. But if one side is heavier, the fulcrum has to work a bit harder. The neutral wire is like that fulcrum, only working harder when the phases are out of balance.

So, there you have it, the neutral cable size is half of the phase cable size because it's designed to handle the imbalance current between phase A and phase B. It's not that it's less important, it's just that it's designed for a different role in the electrical symphony.