The neutral is at zero potential, theoretically, but there can be a small potential on it if it's carrying enough current because it has a finite amount of resistance. That's why the neutral is always grounded in your panel. You cannot get a shock from a properly installed neutral.
Your body has approximately 10K to 50K ohms resistance so if you touch a hot wire you are completing the circuit to ground, which is called fault current, and whose fault would it be? At 220V, it only takes a handful of milliamps to kill you.
Bill
Your body has approximately 10K to 50K ohms resistance so if you touch a hot wire you are completing the circuit to ground, which is called fault current, and whose fault would it be? At 220V, it only takes a handful of milliamps to kill you.
Bill
I'm not sure where this is going...
In the original question I assumed we were talking mostly about circuitry like amps, preamps and things beyond the mains. In that case current flows because you turned the device on and applied a power supply to the circuit. Current flowing is a given and it flows through the wires. The wires have resistance along their length, so they have resistance between any two points, A and B. Apply Ohm's law, V=I*R. The amount of current flowing is likely determined by other circuit components, hopefully not the wire. Say you have an amp of current flowing in a speaker wire (maybe the peak positive instantaneous value of a drum beat). If a foot of speaker wire has a resistance of .003 ohms (I've no idea, made that up), then 1A * .003 = .003 volts. So there's your current and your voltage. If you've got twenty feet of wire, the voltage difference between one and and the other will be 0.06 or 60 mV. This isn't difficult, but you have to look at one small area at a time until you can put the big picture together.
The mains voltage is fodder for another post.
In the original question I assumed we were talking mostly about circuitry like amps, preamps and things beyond the mains. In that case current flows because you turned the device on and applied a power supply to the circuit. Current flowing is a given and it flows through the wires. The wires have resistance along their length, so they have resistance between any two points, A and B. Apply Ohm's law, V=I*R. The amount of current flowing is likely determined by other circuit components, hopefully not the wire. Say you have an amp of current flowing in a speaker wire (maybe the peak positive instantaneous value of a drum beat). If a foot of speaker wire has a resistance of .003 ohms (I've no idea, made that up), then 1A * .003 = .003 volts. So there's your current and your voltage. If you've got twenty feet of wire, the voltage difference between one and and the other will be 0.06 or 60 mV. This isn't difficult, but you have to look at one small area at a time until you can put the big picture together.
The mains voltage is fodder for another post.
Everybody has to start somewhere. When I was a small child I carefully unscrewed my night light bulb and inserted my little finger in the socket. I then turned on the switch with my other hand. That was my "jump-start" in electronics, and I've been at it ever since. Hopefully others can learn from our hard won knowledge so they don't have to engage in their own original research on the matter.
Conrad I performed same experiment in my budding youth, funny refused to learn to arc weld until I was 18. While it doesn't answer the primary questions I have used this link as a guide line to power wiring. The proper ground lug seems over kill but I have cleaned up several hum issues by going back and implementing it .
http://sound.westhost.com/earthing.htm
Bill
http://sound.westhost.com/earthing.htm
Bill
I'm going to come back to the previous issues later but I have one question about grounding related to my current amp project.
The chassis is made up of three pieces of steel. The top, bottom and the sides (and front panel too actually).
I am supposed to connect the bottom to the ground at the mains but can I connect it any other panel such as the side?
And then perhaps the screws which hold the top, bottom panels would provide an electrical connection to the ground? and if I scratched abit more to make the connection better, would this be acceptable?
The chassis is made up of three pieces of steel. The top, bottom and the sides (and front panel too actually).
I am supposed to connect the bottom to the ground at the mains but can I connect it any other panel such as the side?
And then perhaps the screws which hold the top, bottom panels would provide an electrical connection to the ground? and if I scratched abit more to make the connection better, would this be acceptable?
you can connect the mains earth wire to any of the panels.
But there are three conditions.
1.) it must be permanent.
2.) it should be close to the incoming mains cable.
3.) it should remain safe if you start dismantling.
This last can be met by coupling all the conductive panels together with welded on terminals and all interconnected with robust, flexible, cable with mechanically fixed fasteners.
But there are three conditions.
1.) it must be permanent.
2.) it should be close to the incoming mains cable.
3.) it should remain safe if you start dismantling.
This last can be met by coupling all the conductive panels together with welded on terminals and all interconnected with robust, flexible, cable with mechanically fixed fasteners.
an Audio system willwork without a connection tothe mains earth.Professor smith said:
For sound and amplifier operation one does not need an earth.
But, for Safety a mains earth connection is mandatory (see exception).
All exposed conductive parts must be connected to Safety Earth.
Exception:
equipment built and tested to the Double insulated standard dispenses with the Safety Earth connection.
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