# How does AC have a Live(Hot) and a neutral wire?

1. ## How does AC have a Live(Hot) and a neutral wire?

I have read many books and search on internet but never able to find the right answer. I hope some one will solve my confusion.

We know that DC never changes it direction so one wire always have maximum potential while other wire always have 0 potential.

There may be two possibility of AC,
1)
On first half cycle one wire is at max potential while other is at 0 potential but on next half cycle the wire which was at max potential will be at 0 potential while other which was at 0 potential will be at max potential as shown in figure below,

2)
On first half cycle one wire will be at positive max potential and on next half cycle this wire will be at negative max potential while the other wire always remain at 0 potential. As shown in figure below,

Can someone explain which concept is correct.

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2. ## Re: How does AC have a Live(Hot) and a neutral wire?

option 2 is correct.
you always see that in the pair of AC supply, there is one live wire (or hot wire, you can check by a tester) and the other ground.
signal is always at live wire. you can touch the groud easily, but not live wie.

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3. ## Re: How does AC have a Live(Hot) and a neutral wire?

In AC power for homes, they secondary of the step down transformer has a center tap that is called neutral and it is also grounded with a deep pole to moist soil. They call it single phase but these two lines are complementary phases Line 1 & Line 2 and 3rd wire Neutral is close to 0V.

In DC they ground the negative pole to the chassis on cars, but at one time the British auto maker MGB used positive ground. So the battery hot terminal read negative with respect to ground.

For what it's worth....
Tony

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4. ## Re: How does AC have a Live(Hot) and a neutral wire?

i think the alternating power signal is always flow in the live(Hot wire) while Neutral is its returning path where this signal completes its circuit. thus we can say the live wire changes its potential continuously from positive peak to negative peak. another interesting experiment that i mostly do is the measurement of ac current using clamp meter. it will show approximately equal currents. thus i can conclude that the neutral wire is the returning path of the current flowing through live. and if our hand is touched to the live wire we will be its return path... thats why neutral wire have no current to cause shock. thus the power sin wave in live wire changes from negative to positive peaks... so your second option is true.

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5. ## Re: How does AC have a Live(Hot) and a neutral wire?

It's all relative. Where ever you ground your power, the potential voltage will be zero w.r.t. ground.
Since Neutral is grounded at the step down transformer near residence.

The current however will be the same sinusoidal ac waveform throughout the entire loop for a linear load.

Birds can sit on the high potential lines and not get fried because their reference is the hot line, so there is no potential difference between birds or feet.

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