Neutral wire has a V same as ground i.e almost 0. Also it carries some current. So if we touch the wire don't we to become a part of the circuit? Even if we are on the ground and current should flow through us, but I read we don't get a shock as there is no potential difference between ground and neutral wire, but the current was already flowing from live wire (220 V) to 0, so shouldn't we get a shock?
[Physics] Why don’t we get a shock touching neutral wire
electric-circuitselectric-currentelectrical-resistanceelectricityvoltage
Related Solutions
[Physics] When we get an electrical shock, the ciruit is incomplete but still the current flows, why
Copying from the electronics.SE
Since in properly constructed power network the neutral wire is maintained at a potential level close to ground potential, there is nearly no voltage between the neutral and the ground. Hence, touching neutral will not cause current to flow through human body into ground.
So by construction there is very little potential between the ground and the neutral. When a human touches the live wire he closes the circuit with the ground instead of the neutral because there is by construction so little difference between neutral and live.
Electrons do "fill up your body" when you jump up and hit a high voltage wire - there is a property called the capacitance of the body that determines how much the voltage increases when you add a certain amount of charge - mathematically, $C = \frac{Q}{V}$.
But it's not charge that kills you, it is current: charge flowing per unit time. Since it takes relatively few electrons to bring the body up to 30,000 V or so, there is not much charge flowing and nobody gets killed. But you may have noticed a static "shock" when (especially in winter) you walked across a carpet, then touched a metal door and got a shock. As you walked across the carpet you built up static charge (with an associated potential that could reach several 10's of kV); and all that charge "leaks away" when you touch a grounded (conducting) surface. But while you can "feel" the current it's not enough to kill you.
So how much charge is there on your body when you are charged to 30,000 V? It's a bit hard to estimate the capacitance of a human body, so we'll use the physicist's trick of the "spherical cow": we approximate the human body as a sphere with 1 m diameter. The capacitance of a sphere is given by
$$C_{sphere} = 4\pi\epsilon_0 R = 0.11 nF$$
At 30 kV, that gives a charge of 3.3 µA; if that charge comes out of your body in 1 µs*, it would result in a peak current of 3.3 A which is why it feels like quite a jolt; however, the total amount of energy is only $\frac12 C V^2 = 0.05 J$ - and that is not enough to kill you. It's enough to kill sensitive electronic circuits, which is why you have to be careful how you handle "bare" electronics, especially in winter (low humidity = build up of static electricity as conductivity of air is lower).
EDIT
- if the current flows in 1 $\mu$s, that suggests that the time constant of body capacitance and skin resistance should be on that order. Since time constant is RC, solving for R gives about 10 kOhm. That’s a rather low resistance: skin resistance is higher, so peak current will be lower.
Best Answer
Do not touch even the neutral wire in a live circuit! There are numerous failure modes that could make you dead wrong about not getting shocked.
The neutral wire does have current going through it. However, we do not get shocked when we touch something with current going through it, we get shocked when current goes through us. In this case all of the current that enters one end of the section of wire we are touching also leaves the other end. None goes through us so we don’t get shocked.
Why does no current go through us? From the perspective of a circuit we are, to a first approximation, just a big human shaped resistor. The current through a resistor is proportional to the voltage across it. Since the neutral is at the same voltage as the ground, both our head and our feet are at 0 V. So the voltage across us is 0 V and therefore the current is 0 A.