power

[ben schaefer]

why when i touch a neutral wire why don't i get shocked? if ac electric flow travels back and forth and it runs on 60 hz then every 60th of a second i should get shocked from touching the neutral wire. same with 240 volt circuits why do you put both ends i to breakers? if any way it travels back and forth on both wires? some one please help me im so confused!

 

[petersonra]

why when i touch a neutral wire why don't i get shocked? if ac electric flow travels back and forth and it runs on 60 hz then every 60th of a second i should get shocked from touching the neutral wire. same with 240 volt circuits why do you put both ends i to breakers? if any way it travels back and forth on both wires? some one please help me im so confused!

how do you know that if you touch a neutral wire you won't get shocked? have you tried it?



The answer is that in most cases, the neutral wire is bonded at its source to earth and to all the metal parts that surround the conductors. We call this a grounded conductor. Thus there is very little in the way of voltage between the neutral wire to earth or ground or metal parts.

Keep in mind that in some cases the conductor that is bonded to earth is not an actual electrical neutral point. It is still a grounded conductor, but is not a neutral.

In residential electrical systems the neutral is generally the grounded conductor. In fact, it might well be a requirement.

 

[kwired]

why when i touch a neutral wire why don't i get shocked? if ac electric flow travels back and forth and it runs on 60 hz then every 60th of a second i should get shocked from touching the neutral wire. same with 240 volt circuits why do you put both ends i to breakers? if any way it travels back and forth on both wires? some one please help me im so confused!

The simple answer - most systems with a "neutral" have that neutral "grounded". You are likely standing on or touching other "grounded" objects so there is no potential between you and that "grounded neutral conductor". Touch one of the other "ungrounded" conductors while touching anything "grounded" and you are subjected to what ever voltage exists between them, often at least 120 volts, but sometimes maybe even more then that with typical premises wiring systems.

Now throw in some complications such as a bad connection in said neutral conductor or voltage drop and you start to develop some voltage between touch points but that is probably a different lesson to learn about.

 

[GoldDigger]

For 120/240 volts and a 240V load, opening either if the two breaker poles will stop current through the normal load.
But it will not necessarily interrupt fault current through the other wire to neutral or ground, nor will it make it safe to touch wires connected to the load. You would complete the circuit.
As for the neutral, even though current is flowing back and forth through the neutral, it is happening at zero voltage. There is no reason for the current to flow through you instead (unless you break the neutral wire and complete the circuit with your body instead.)

 

[Besoeker]

why when i touch a neutral wire why don't i get shocked? if ac electric flow travels back and forth and it runs on 60 hz then every 60th of a second i should get shocked from touching the neutral wire. same with 240 volt circuits why do you put both ends i to breakers? if any way it travels back and forth on both wires? some one please help me im so confused!

It's a voltage difference that can shock you.
Think about what that means.

 

[kwired]

It's a voltage difference that can shock you.
Think about what that means.

Take that one step further - you can touch the "hot" wires and not get shocked if you are insulated from other points of potential, including "ground" in this case as it is different potential.

 

[Besoeker]

Take that one step further - you can touch the "hot" wires and not get shocked if you are insulated from other points of potential, including "ground" in this case as it is different potential.

Quite.
No voltage difference.

 

[tom baker]

Si hoc legere scis nimium eruditionis habes.
I had to look this up. My tag line is Anacora Impara

 

[charlie b]

Not so fast! It is still possible to get shocked if you touch a hot wire but are insulated from ground (rubber shoes and rubber mat). It won't be as bad a shock as you would have gotten with bare feet on grass, but it still could be unpleasant. Between any two conductive surfaces in the universe (say, for example, your body and the garage floor), there is a value of capacitance. Think of your rubber shoes and the rubber mat as serving as a dielectric material, much like the material that separates the parallel metal plates of a capacitor. So don't try this experiment at home. It is not safe to do so.

 

[fmtjfw]

Not so fast! It is still possible to get shocked if you touch a hot wire but are insulated from ground (rubber shoes and rubber mat). It won't be as bad a shock as you would have gotten with bare feet on grass, but it still could be unpleasant. Between any two conductive surfaces in the universe (say, for example, your body and the garage floor), there is a value of capacitance. Think of your rubber shoes and the rubber mat as serving as a dielectric material, much like the material that separates the parallel metal plates of a capacitor. So don't try this experiment at home. It is not safe to do so.

At or about 22KV the air is a good enough conductor that birds will not land on an energized line. The current leakage shocks them. At higher voltages (>138KV?) men doing bare hands work on a line whilst in an insulated bucket or transferring from a helicopter connect to the line and work in a cage or a conductive suit.

 

[Besoeker]

Si hoc legere scis nimium eruditionis habes.
I had to look this up. My tag line is Anacora Impara

But should it be ancora imparo?

 

[charlie b]

I thought it was occulus repairo. :lol:

 

[Besoeker]

I thought it was occulus repairo. :lol:

Very good.......
Oculus Reparo..............
Not a Harry Potter fan myself.

 

[kwired]

Not so fast! It is still possible to get shocked if you touch a hot wire but are insulated from ground (rubber shoes and rubber mat). It won't be as bad a shock as you would have gotten with bare feet on grass, but it still could be unpleasant. Between any two conductive surfaces in the universe (say, for example, your body and the garage floor), there is a value of capacitance. Think of your rubber shoes and the rubber mat as serving as a dielectric material, much like the material that separates the parallel metal plates of a capacitor. So don't try this experiment at home. It is not safe to do so.

How much voltage is necessary to make this likely though? I've contacted 120 volts to ground many times with nothing happening. Linemen have for years done bare handed work on at least 7200 volts to ground while otherwise insulated, but you are not seeing as much of that as you once did.

 

[Besoeker]

A somewhat related tale I have probably posted before.

I grew up on a farm and we occasionally used to fence off a piece of grazing land with temporary electric fencing. This was used to isolate an individual cattle beast.The electrification was produced by a circuit much like a car engine ignition system. Pulsed at about one or two second intervals. The shock was enough to keep the cattle beast off it.

One evening when I was maybe about fourteen, I was out with my dog. The macho thing was demonstrate that you could grasp it and hang on to it.
I did. With my right hand. My left dangled by my side. The dog gave me what I'm sure, in other circumstances, would have been an affectionate snuffle.
Wet nose, wet grass, no insulated boots.
We both got the most unpleasant shock. From my right hand to my left to the poor dog's nose to his wet paws.

Didn't do his nerves any good. But his good nature and gentle demeanor returned in a day or two.

Insulation matters...........