If AC voltage is alternative, why there are two (Suppose there is no earth wire) wires attached to the wall socket: live or hot, neutral wires? And I think that in small home generators there is no need to specify which wire is the live wire?

I've read that the neutral wire is connected to the ground. Where it's connected, I mean at the house or somewhere else ?


There must be two wires for a complete circuit.

Now, in a balanced AC circuit, both wires provide an alternating voltage with respect to ground (earth). When one wire is positive, the other is negative.

However, in an unbalanced system, one wire is neutral, which should ideally be at 0V with respect to ground, and the other is hot which alternates positive and negative with respect to ground.

In either case, both wires have (ideally) equal and opposite current.

If I'm not mistaken, in the USA, the neutral and ground are connected together at the meter base (service entrance).

For a generator that isn't referenced to ground, the AC voltage is simply across the 'hot' and 'neutral'.

There are devices for converting unbalanced AC to balanced AC power.

  • \$\begingroup\$ That first article seems to ignore the safety implications of having a balanced AC circuit. \$\endgroup\$ Oct 26 '14 at 6:25
  • \$\begingroup\$ Thank you, @Alfred .. Please correct me if i'm wrong --in unbalanced AC circuits,the neutral is connected to the ground(Earth, in this case),and if the 'hot' wire is denoted as L and the neutral as N, the following is happening: For the first positive half of L's voltage cycle, the electrons are moving from L to an appliance then to N which is connected to earth(at some point). At the second -Negative half- of L's voltage, it's now negative with respect to the ground(earth,which is 0V), the electrons now are moving from N (earth, because N is connected to it) to the appliance then to L? \$\endgroup\$ Oct 26 '14 at 14:05
  • \$\begingroup\$ And does the earth in this kind of systems considered as the second wire that completes the circuits? \$\endgroup\$ Oct 26 '14 at 14:08
  • \$\begingroup\$ @MustafaAliraqi, that's not quite correct. The earthing of the neutral wire simply sets the voltage on the neutral to 0V with respect to earth. However, there is no (or should be no) current into or out of the ground (earth). That is to say, the circuit is still complete even if the neutral is disconnected from ground. \$\endgroup\$ Oct 26 '14 at 14:09
  • \$\begingroup\$ This is exactly what confusing me, @Alfred .. How does electrical current flow from the Neutral wire to the Line wire through the device in the second half and yet it doesn't shock us when we touch it and we don't call it a hot wire. \$\endgroup\$ Oct 26 '14 at 14:23

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