Originally posted by: RedSquirrel
What is the technical difference between neutral and hot? since really, the + and - changes ever 1/60 seconds anyway. I always figured you don't get shocked because the electricity takes the easiest path rather then go through you (and the ground/socks/shoes provide enough insulation so you don't create a circuit).
It's like if you put a paper clip in the socket. There are decent chances you won't get a shock if the conditions are right. Now if you're bare feet on the cement you probably will. If you put two paper clips, one on each side, and touch both then it will light up your life. 😱
Note: do not try this, not very smart. 😛
Hopefully, you know what a van de graaff generator is - the big ball that if you have your hand on it, and you're insulated, your hair stands up. Well, if you go near it, and are grounded, you'll get "shocked" by a big spark. What happened? If the dome on the van de graaff has an excess negative charge, and
you are neutrally charged, then when you move near the van de graaff, some of those electrons are going to move from the van de graaff to you. BUT, by changing the materials to build the pulleys and belts inside the van de graaff, you could make a van de graaff generator that is
positively charged. If you are neutrally charged and go near a positively charged van de graaff and point your finger near it, then you'll be the source of extra electrons. The 60 Hz in the U.S. is the "hot" wire changing from positive to negative and back 60 times a second. (60 times, it's positive, 60 times it's negative.) The other wire doesn't have to have a charge, as the potential difference (voltage) is with respect to ground. Now, during that 120th of a second, the voltage isn't a constant 120V; if you graphed the voltage, it follows a sine curve. However, 120V is sort of an average during that 120th of a second. (RMS Root mean square - it adds up all the instantaneous squares of the voltages, then takes the square root. Calculus sort of required, but the solution is pretty simple.)
[and before I forget, wtf are people talking about "electricity go back"? wtf do you mean by "electricity"? Electron flow? The electrons just wiggle back and forth.]
Now, back to the neutral is "neutral." Unless I'm mis-thinking this, NO, it's not. Reason: wire has resistance. If we're talking about 50 feet of wire between the breaker box & the light, 14 gauge wire, then the 50 feet of hot and 50 feet of neutral each have a resistance of about .1265 Ohms. A 60W bulb has a resistance of about 240 Ohms, so the resistance of the wire is pretty insignificant. But, if the actual voltage at the breaker panel is 120V with respect to ground, then you can consider it to be a series circuit with 3 components: the hot wire, the bulb, and the neutral wire. Just rounding off, you'd have about .5amps; using V=IR, you'd lose .063V in the hot wire, and lose .063V in the "neutral" wire, meaning that there is a very small voltage (with respect to ground) after the bulb.
Now, if you're talking about something with higher current, like a blow drier, then you're going to have a little bit more voltage on the neutral wire. Generally, not a problem if you come into contact with it, because the resistance of human skin is so high.
But, if you're standing in a bathtub, and are wet, when touching that neutral wire, then you form a parallel circuit with the neutral wire to ground. I suppose it's possible in that case for you to detect a current in you. Human threshold for detecting a current is about 1mA. (I don't think it'd be lethal at that voltage, which may explain why lights in a bathroom don't have to be GFI protected?) But, the current in a human only has to be ~50 milliamps (depending on what source you use for this information - I don't have the results experimentally
😉 ) to kill a person. This is where ground fault interrupters are handy - they constantly compare the current in the hot wire and in the neutral wire. If you do something stupid, or an appliance malfunctions and you become the neutral wire, then there will be a difference in currents between the two wires. When this happens, click, the circuit is broken at the GFI outlet. GFI's detect differences in current of as little as 5 milliamps.
A little more info about GFI's:
http://www.electronics-manufac...-interrupter-gfci.html
But again, two requirements for a current: conductor & potential difference.
