since electricity from the power station is in the form of a.c.,why is there a definite live and neutral wire?

Answer 1

For starters you need to understand that electricity must flow in a circuit. In a battery, electricity flows from one terminal of the battery to the other. In a house outlet, power flows from live to neutral. The appliance you plug into an outlet completes the circuit from the live slot to the neutral slot, and electricity flows through the appliance to run a motor, heat some coils or whatever. Let's say you plug a light bulb into the outlet. The power will flow from the live prong, through the filament and back to the neutral prong, creating light in the process.

What if you were to plug a thick strand of wire straight from the live slot to the neutral slot of an outlet? Unlike an appliance, which limits the amount of electricity that can flow (60 watts for a light bulb) or 500 watts (for a toaster), the wire would let an incredible amount of electricity flow through it. Back in the fuse box, the fuse or circuit breaker for the outlet would detect this huge surge and it would cut off the flow of electricity. The fuse prevents the wires in the wall or the outlet itself from overheating and starting a fire.

The ground slot and the neutral slot of an outlet are identical. That is, if you go back to the fuse box, you will find that the neutral and ground wires from all of the outlets go to the same place.

In the UK every appliance has a three-prong outlet, where in countries such as the US only certain appliances have these. The idea behind grounding is to protect the people who use metal-encased appliances from electric shock. The casing is connected directly to the ground prong.

Let's say that a wire comes loose inside an ungrounded metal case, and the loose wire touches the metal case. If the loose wire is live, then the metal case is now live, and anyone who touches it will get a potentially fatal shock. With the case grounded, the electricity from the live wire flows straight to ground, and this trips the fuse in the fuse box. Now the appliance won't work, but it won't kill you either.

What happens if you cut off the ground prong or use a cheater plug so you can plug a three-prong appliance into a two-prong outlet? Nothing really -- the appliance will still operate. What you have done, however, is disable an important safety feature that protects you from electric shock if a wire comes loose.

Answer 2

a.c. is 'alternating current'. That means that it moves one direction, stops, and reverses direction, stops, and goes in the forward direction once again, and it repeats this same process sixty times a second. there is only one wire that carries this 'action' because that is all that's needed. When the 'live' wire is going one direction, there has to be a return path to the power source. (Remember you high school chemistry when you made chemical cell batteries, you had to have a negative and a positive terminal, a complete path to make a circuit.) When the 'live' wire is negative with respect to ground, there has to be a current return path for there to be any electrical current flow. That 'neutral' wire acts as the positive electrode in the battery. Then the current stops, and reverses. Now the 'hot' wire is acting like a positive with respect to ground. And the circuit still needs a current return path, so the 'neutral' acts as that current return path by being the negative of the battery. I suppose they call the wire that does all the changing a live wire because it's doing all the 'dancing' around in the circuit. the 'neutral' wire is just there as a passive element (versus the 'live' wire's active status.) If you have two 'live' wires, then they would both be supplying the 'action' and nothing there is to 'soak-it-up' (Neutral). If you have two neutral wires, there is nothing to provide the 'action' for the neutral wire to soak-up. A very rough analogy, but one that I hope makes sense. Now there are things like two live wires supplying high voltage/current devices, like ranges, dryers, air conditioners and stuff like that. That's where two 'live' wires can share the same neutral, (and often do). But that works on the same principle and is a lot more complicated to get into for now. I hope that clears up some q's you've had.

:-)

Answer 3

I think I understand your question, you have probably got the idea that AC mains 'reverses' or something like that?? NO the neutral pin on a socket or a neutral (Black or Blue wire) is always at or very close to earth potential, however the altenating (A.C.) voltage on the live/phase conductor alternates between zero and 380/440 volts at 50HZ UK, which give a rms voltage to neutral/earth of 230/240 volts. Industrial supplies will have three separate phases, out of sync. by 120 degrees which will result in a higher voltage between any two at any time in the cycle, this allows less current to flow and cable sizes to be reduced.

Joe H is wrong the national grid is AC, and the voltage is reduced at transformers from 186100--765000 volts on the National Grid to 7200 (I think at a local sub-station) then to 240 to homes.

Broad 1- The live and neutral are def. NOT interchangeable at appliances the live should always go to the teminal marked LIVE, or a shock could result from by passing switches/controls.

Answer 4

The live and neutral wires are interchangeable as far as the electrical appliance is concerned,However one of these wires is grounded(earthed) at the power generation source for safety reasons and the definition neutral wire is used to identify which is the grounded wire.The live wire is always the one that is switched and in some cases both the live and neutral are switched for safety reasons

Answer 5

Your question is remarkably greater difficult to respond to than you think of. initially, on your question you're saying "...they use friction to make electric powered and cole to make gas." Neither of those statements is real. electrical energy is made using a generator. A generator makes electrical energy using magnetic fields. A rotor spins interior a stator and that's what "generates" electrical energy. The rotor is often spun using compelled steam. What makes one skill station distinctive from yet another is how the skill station heats the water to make the steam. some stations burn coal, some stations burn oil, some stations burn organic gas, and a few use nuclear fission. businesses that generate electrical energy could desire to purchase the gasoline to warmth the water, purchase or hire the land the station is on, pay the salaries of the employees, pay coverage, etc, etc. so as that they incur particularly some expenses. After the electrical energy is generated there are additionally transmission and distribution rates. (i.e. the skill grid). i won't be in a position to talk as to how those expenses artwork. i'm as puzzled approximately those as you're. finally, skill stations do not use coal to make gas.

Answer 6

The negative is earthed ('grounded') at the power station. To prove this, rig up a lamp in a holder with a length of flex. Connect one of those wires to a live positive terminal in your house - where the brown wire goes in a plug - and touch the other one practically anywhere else - to the conduit piping if your house is old, or poke a metal road into your back garden and use that, or any water pipe that isn't plastic. (But not to a gas pipe please! - and don't touch any part of your body with it!) The bulb will light.
On second thoughts, DON'T try this at home, just take my word for it!

Answer 7

Assume a power station has a 3- phase generator.

It means there are three coils each generating a low voltage of 250 volts between the ends of each of the three coils.

Consider one of the coils alone. The potential difference between the two terminals varies with time, that is it oscillates between 250 V to zero V to minus 250 V to zero V and to 250 V.

Similarly for the other three coils.

The three coils have in total 6 terminals. One end of each coil is connected to one end of the second coil and this common end is connected to one end of the third coil.
Thus there is one terminal as common to all the three coils and three separate terminals.

The three separate terminals are called line and the common terminal is called neutral.

The potential difference between the neutral and line varies from250 V to zero V to minus 250 V to zero V and to 250 V.

The potential difference between two lines varies from400 V to zero V to minus 400 V to zero V and to 400 V.

Our lamps and other electrical appliances are usually connected between a line and neutral.

But for running heavy machinery we make use of two or three phases A.C

Neutral implies, this wire is connected to the common junction of the other two coils in the generator even though for housing purpose we don’t bother about the other two line wires.

Even though for housing purposes it is not a matter which is line and which is neutral, from the generator point of view a line is different from neutral.

Imagine a generator having only one coil and generates 250 v.

There will be two terminals and our bulb will be connected to the two terminals alone. In that case we can't differentiate which is line and which is neutral.

Answer 8

Yes the one is grounded at the power station----jatktee96 yu got it wrong when you say you can not swap the two around,What about appliances used and supplied with two prong plugs,for instance hair dryers,hair tong and cell phone chargers,these are used all over the world and can be plugged in any way around,Goes to show u 45yrs in the trade means zilch.dont try and tell me about double insulation

Answer 9

Think in terms of water.

Live is the supply pipe. Neutral is the correct return path. Earth (local) is the emergency dump.

ps. The neutral is actually 'earth' - in the grand scheme of things.

Answer 10

They all seem to say that electricity come down one wire and goes back up the other. If it does why do I have to pay for it if they are getting it back?