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So I looked this up in multiple places but could not get an answer that makes sense in my head. To be clear, I am not here to debate, but understand. Let's say I am not using any 240V circuits in my house in the US, and I stupidly go and unscrew a receptacle plate and touch the neutral wire with my hand. ASSUMING it is properly connected (no faults and bonded to ground at mains) why is it I don't get a shock? And more-over to my understanding of AC power, how is the ground cable then not carrying at least some current?

If I am not using any 240V circuits then all or most the current going from the hot should return via the neutral wire, so why is the neutral not just as dangerous to touch? Both neutral and ground cables are basically small resistors which make them good conductors (albeit ground is lower resistance), but no big capacitve or inductive load comes into play that I know of. Some people say it is because the Earth ground bonding makes the potential between neutral and ground the same. But wouldn't that mean that the ground cable being the same potential then would also carry at least some current? Current doesn't just disappear so if it goes out the neutral, would ground carry it too? Or maybe better stated if ground is almost 0V then in most applications wouldn't neutral be almost 0V too? If that is true then where does the +- 120V from the hot wire go? This thought has been driving me crazy!

P.S. You may need to include pictures for my thick brain

1 Answers1

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ASSUMING it is properly connected (no faults and bonded to ground at mains) why is it I don't get a shock? And more-over to my understanding of AC power, how is the ground cable then not carrying at least some current?

By bonding the neutral conductor to ground at the service panel, the neutral conductor is close to ground potential. I say "close" because, unlike the equipment grounding conductor (safety ground) which does not carry normal load current (only fault current), the neutral does. Therefore there will be a voltage drop along the neutral equal to the load current times the ohmic resistance of the neutral wire.

If everything is working properly, the neutral voltage to ground should be below the level that involves a risk of electric shock. I emphasize properly working, because if there is an open circuit or high resistance connection along the neutral conductor, the voltage may equal or approach line voltage posing a risk of electric shock hazard.

Bottom line: To avoid a risk of electric shock, never purposely touch the neutral conductor or stick something into the wide (neutral) slot of the receptacle.

Actually this makes sense! So just to be clear, both the ground wire and neutral wire under my conditions would be carrying some voltage, but not enough to shock correct? By ground I mean the Earth grounding rod outside your house because that is connected from neutral bonding to ground so if I understand correctly that would be a complete circuit if I were to touch the outside rod

The equipment grounding conductor normally carries no current and therefore no voltage. The grounded circuit conductor (neutral) carries load current and therefore carries a voltage equal to that current times the resistance of the conductor. But that voltage is normally too low to pose a risk of electric shock.

I think it is important to understand the meaning of the term "grounded" in connection with to these conductors. The schematic below may help in that regard.

The following terminology is used in the US National Electrical Code (NEC)(NFPA 70) for the three branch circuit conductors of a nominal 120 vac circuit are

  1. Ungrounded circuit conductor (a.k.a the "hot" or "live" conductor)

  2. Grounded circuit conductor (a.k.a, the "neutral" conductor)

  3. Equipment grounding conductor (a.k.a, the "safety ground")

These are the three conductors circled in the schematic for a single branch circuit.

The first thing to realize is that the equipment grounding conductor normally carries no current. It only carries current under fault conditions. That means the grounding pin on the receptacle shown has no voltage with respect to ground. If a fault occurs (e.g., failure of insulation between the "hot" conductor and ground) the branch circuit overcurrent device (or a GFCI if provided) is intended to clear the fault limiting the duration of the fault voltage, reducing the risk of electric shock.

The neutral conductor carries load current back to the neutral bus on the service panel. That bus is bonded to the equipment grounding bus as well as to the building grounding electrode. The load current between the neutral connection at the receptacle and neutral bus, the path shown in red, causes a voltage drop. The resistance of 100 feet of 14 AWG copper wire is about 0.25 Ohms. Multiplied by the max load current of 15 amps gives a voltage drop of only 3.75 volts.

However, the diagram shows only a single receptacle on the branch circuit, which is called a dedicated branch circuit. General 15 amp branch circuits however have multiple receptacles. Each receptacle involves connections and the possibility of a loose or open connection. If there was an open connection the voltage on the neutral downstream will rise to line voltage posing a risk of electric shock. This is what I meant when I said the neutral to ground should be below the level that involves risk of shock, provided that everything is working properly.

Hope this helps.

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Bob D
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