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# Electricity and the live/neutral wires Watch

1. How do they work? If you have an AC current flowing, wouldn't there be current flowing both ways?

From what I think it might be, there actually is current flowing through both wires, but the neutral wire is grounded, so current won't pass through a person touching it on its own. But if this is the case, why wouldn't there be a short circuit from the power supply into the ground?

I'd appreciate it if someone could show me a diagram of the system; I tried googling on this but I got irrelevant results.
2. (Original post by valhalla92)
How do they work? If you have an AC current flowing, wouldn't there be current flowing both ways?

From what I think it might be, there actually is current flowing through both wires, but the neutral wire is grounded, so current won't pass through a person touching it on its own. But if this is the case, why wouldn't there be a short circuit from the power supply into the ground?

I'd appreciate it if someone could show me a diagram of the system; I tried googling on this but I got irrelevant results.
Earthing/Grounding
It just means that the live terminal goes from +240V to -240V (or whatever the ac voltage is) while the other one stays at zero.
Without the earthing, both terminals go from +120V to -120V. One is at +120 while the other is at -120 to give the 240 difference.
If the earth terminal stays at zero, ground potential, it means that if you touch it there is no pd between you and earth and you get no shock/current.
If it was not grounded you would get the -120 to +120V pd and the resulting shock.
3. (Original post by Stonebridge)
Earthing/Grounding
It just means that the live terminal goes from +240V to -240V (or whatever the ac voltage is) while the other one stays at zero.
Without the earthing, both terminals go from +120V to -120V. One is at +120 while the other is at -120 to give the 240 difference.
If the earth terminal stays at zero, ground potential, it means that if you touch it there is no pd between you and earth and you get no shock/current.
If it was not grounded you would get the -120 to +120V pd and the resulting shock.
If the supply is rated at 240V AC, then strictly speaking its +340V to -340V for the live as 240 is the rms value. Neutral is meant to be at earth potential so is earthed at the local utility station.
4. Yeah same current in both Live and Neutral wires. fwiw if it's different - it's a fault and the RCD (if fitted) will trip.

don't assume it's always safe to touch neutral in the real world though cos it might not be.
5. (Original post by eswnl)
If the supply is rated at 240V AC, then strictly speaking its +340V to -340V for the live as 240 is the rms value. Neutral is meant to be at earth potential so is earthed at the local utility station.
... that's why I added in brackets "or whatever the AC voltage is" because I knew someone would add that either
• it's not 240V in the USA or some other country
• it's the rms not the peak voltage, etc

The point is not the actual rms or peak value, but why the one side is grounded.
Thanks for mentioning it, though.

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