Home Electrical AC Wiring Layout & Estimation Questions
Don't fall into the "neutral is ground" myth.

Electricity flows in loops.  It takes 2 wires on every circuit. 

Hot AND neutral are the two partner wires that carry power to your appliances.  Expect to use them in roughly equal proportion.  

You absolutely must not treat neutral as a "common/chassis/backplane" and simply have a bunch of circuits' hots share the same neutral.  That will set your neutral wire on fire.  Which, granted, won't do a whole lot in conduit inside concrete, but you will be forced to rewire at the least.  



Safety ground is a totally different thing.  It is a safety shield.  Current never flows on ground (except during fault conditions, of course).  

While it's true that neutral and ground are connected at the main panel, don't think they are somehow the same.  The purpose of the connection is to a) keep hot/neutral from floating at thousands of volts above ground, e.g. due to a transformer leak.  And b) current flows in loops, and that allows fault current that got on ground somehow, to loop back to neutral - and flow enough amps to trip the breaker.   

It's possible to do isolated systems where H-N is not connected to G at all.  However that can cause problems.  

Because of this, safety ground can be shared among multiple circuits (the ground wire must be large enough for the largest of the circuits sharing it).  As such, you need as much ground wire as you have conduit length.  

If you use metal conduit -- wait, you can't use metal conduit in concrete! It will corrode. 

As far as hot wires, they don't give out medals for saving wire.  Use as many hot wire colors as your country's electrical codes will allow - this will be very helpful when trying to distinguish one wire color from another.  I own 8 colors of hot myself and 2 of neutral.  



You are not subject to the special case in about half of the Philippines (the legacy USA territories), where power is unusual. (two hots, each 120V from ground. Effectively, neutral does not exist in those territories, and this is a big bag of Not Your Problem.  Just be aware those territories do exist, and about half of Philippine advice will apply there.  So if you see stuff about 2-pole breakers and 2-pole switches, that is that, and doesn't apply to you.