Does the neutral conductor carry current during normal working condition in a house?

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1. Apr 1, 2017

Manoj Sahu

I read in a book that during normal working condition (balanced system) the current through a neutral conductor is zero i.e., Ia+Ib+Ic =0 where Ia, Ib, Ic are phase current of three different phases a, b, c. How is that possible? I mean if you look at mathematical result of the phases they are parted by 120' each.

2. Apr 1, 2017

cnh1995

In a balanced three phase system, neutral current is always zero.
Plot the phasor diagram and see the resultant. It should be zero.

In your thread title, you've mentioned residential load. Residential supply is single phase supply and the neutral carries the same current as the phase wire.

3. Apr 1, 2017

jim hardy

Get out your drafting tools and add three of equal length separated by 120 degrees .
You'll wind up back where you started, at the origin 0, 0

On the incoming wires from the pole to the beaker panel , neutral carries the difference between currents on the two phase wires, in other words the imbalance, just as in three phase.

4. Apr 1, 2017

cnh1995

Thanks @jim hardy for that edit.
I was talking about Indian supply system: 230V with one hot and one neutral.
So our residential neutrals never carry zero current.

But as you said, phase and neutral currents are equal indeed "within any single branch circuit".

5. Apr 1, 2017

jim hardy

Ahh that never dawned on egocentric me ! [ Sheepish grin icon ]