Finally found something which clearly makes a difference between what might be common in the US or in Europe !
http://www.eetimes.com/document.asp?doc_id=1272972
For example:
"
Myth: A computer treats the neutral wire differently from the hot wire.
International office product safety regulations (including IEC 950 and UL 1950) prohibit these wires from being treated differently. Each is considered a safety hazard under the regulations and is required to be disconnected from and have appropriate safety spacings from logic circuits. Furthermore, inspection of the wiring schematics of any computer equipment clearly shows that the input hot and neutral wires are connected to the same circuits in the same ways and are interchangeable. Belief in this myth is very uncommon in Europe since anyone can see that a European plug can be reversed.
"
That is what i mean with the 2 hot wires, they're both hot / dangerous and only the 3rd wire is earth.
Not sure how it is in the US but i see people talk about mains AC and mention HOT and NEUTRAL and GROUND (EARTH), so this makes it confusing since AC has no polarity.
So the question is, what is this NEUTRAL wire ? Why call it NEUTRAL at all when it comes to mains AC ?
PS: I'm reading / learning more about this but any info is always appreciated guys !
Think i found it explained, i will paste the relevant part so other newbies can understand this thing better:
"...
The reason that one of the power wires is named "neutral" is because it is connected directly to the building ground connection at the circuit breaker panel. Therefore it is connected directly to the grounding (third) wire. In essence, then, two of the three wires at the wall receptacle are actually grounded wires, one being used for power flow, and the other connected only to exposed metal parts on the equipment. The power wire that is grounded is called the "neutral" wire because it is not dangerous with respect to exposed metal parts or plumbing. The "hot" wire gets its name because it is dangerous.
The grounding of the neutral wire is not related to the operation of electrical equipment but is required for reasons of safety. To reduce the chance of electrical shock, it is important to provide a means to automatically shut down the electrical circuit if an exposed metal part becomes accidentally connected to a hot conductor or circuit. This is accomplished using the 3-wire system by an ingenious technique:
Every electrical circuit is protected by a circuit breaker. The purpose of the circuit breaker is to prevent the building wiring from overheating as a result of excessive user loads being plugged in. However, in the 3-wire system, the circuit breaker provides another critical safety function. If a hot wire or circuit were to become accidentally connected to an exposed metal part on a piece of equipment, then a shock hazard would exist. However, if the exposed parts are connected to the grounding wire, then the hot wire becomes connected to the grounding wire. This would not cause anything unusual to happen except for the fact that the second power wire, the neutral wire, is also connected to the grounding wire at the circuit breaker panel. Therefore, for this safety hazard the grounding wire essentially becomes connected as a load. The low resistance of the grounding wire causes it to draw a very large amount of current when it becomes inadvertently connected as a load, which in turn causes the circuit breaker feeding the hot wire to trip. Therefore, the 3-wire system operates in a manner which transforms a safety hazard into an over current condition, causing the safety hazard to be automatically cleared by the circuit breaker. The circuit breaker is used as both an over current protector and a shock hazard protector.
...
"
Electricity authorities are deeply distrustful folk,& assume that either,some sockets will be wired with Live & Neutral reversed,or that you may be in a country where the plug can be reversed.
Accordingly,they require the same level of insulation for both conductors,so that if what would normally be the Neutral connection inside the appliance,with little or no potential to the Earth,& hence Earth/Neutral connection back at the house supply entry point,now becomes the Live connection,there will be no safety or operational problem.
This can be very important,as the following anecdote shows:-
Back in the early 1970s,I was involved with the installation of a Closed Circuit TV system.
The pan & tilt heads for the cameras were unusual,in that they operated from the Mains,using appropriately rated cable to make the connections between the control room & each such device.
A test box was made up which could be plugged into a nearby GPO,& switched the Live mains leg to each motor in turn.
We had to stand on a ladder & adjust stops which operated microswitches ---these prevented you "panning" or "tilting" your camera lens into a wall or other obstacle.
All went well,till I was adjusting one of these stops,received a nasty shock,fell off the ladder,& ended up on the floor.
On investigation,we found that the manufacturer had insulated the "Live" wiring well,but hadn't worried about the "Neutral".
I,of course,had "hit the jackpot"----a GPO with reversed connections!
That said,as far as the power outlet is concerned,with a
correctly wired normal 220v single phase supply,the only "hot" socket pin is the live or "Active" pin.