Why is there no current in the neutral wire? | Page 2 | on ElectriciansForums

Discuss Why is there no current in the neutral wire? in the UK Electrical Forum area at ElectriciansForums.net

Q

QueenZ

Hello. It doesn't make sense to me why there is no current in the neutral wire, I can touch it and there is nothing but there is electricity in the hot wire... But as far as I understand, AC generator generates electricity in both wires, so why are we not getting it in our homes? What did they do to the other wire and why? Thanks!
 
what is the purpose of the neutral wire? Why do we need to ground one of the wires? The circuit works just fine if you don't have a neutral wire... have you never made an AC generator and a diode that lights up? but you haven't grounded any of the wires (making a neutral wire) and it still works.... so what's the point?

somebody answer this one...
 
OK - Imagine trying to stretch a rubber band - it's impossible to do it with only one finger, right? It doesn't matter how big or small you try to drag the top to, you still have to have a finger on the bottom.

So it is with electricity: In order for a voltage to be either a big number or a small one, it has to be relative to something else, and in this case our 'bottom finger' is the neutral. Just like a rubber band, the more tension (which also happens to be a term used for voltage sometimes) there is if you let go, the bigger the thwack you get on your thumb (normally accompanied by swearing and slight pain). If you stretch your rubber band up as far as it will go, keep the top finger in position but then move the bottom one up so it's flat again, you've moved your imaginary voltage up and up, but there's no actual thwack left as it's all at the same level. This principle (which I hope has made things clearer) we call Potential Difference (pd) and we use the unit of Volts to measure it.

And the reason that in the electrical sense we keep our bottom fingers stapled to the Earth is because it's the safest thing to do (and easiest and most prolific conductor that we have).
 
Grounding the neutral at the source not anywhere else gives you a third wire Earth which is used for safety purposes in case of fault, it provides an alternative route for the current and if L/E fault the fuse or trip protecting it will operate making the circuit safe. Without earth been at the same potential as neutral, faults can create a dangerous situation or go undetected.
Also to note alot of electronic gear now uses earth to get rid of 'noise' which can interfere and cause problems with other loads.
 
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somebody answer this one...

You dont NEED to do it but we choose to do it for very good reasons.

Try disconnecting a neutral wire under load and you will see it is doing a very useful job, you will see sparks and the load will stop working. Second thoughts dont you might get a shock
 
A safer alternative is to erect a simple light circuit from a plug and put the neutral in the switch. Plug it in and switch the neutral off and on and see what you get on your approved voltage tester at different points of that circuit.

Only do this if you are competent to do so safely, or ask the tutor.
 
what is the purpose of the neutral wire? Why do we need to ground one of the wires?
somebody answer this one...

Because of the double earth fault probability,the people charged with keeping the supply going would be going bonkers

Imagine a supply transformer with the star point of the transformer not connected to earth
The local factory has a phase faulted to some metalic machinery that is in contact with earth,evrything works fine and no issues
They or another factory then has a seperate piece of machinery that also decides to fault,this time a different phase makes the metallic part in connection with the ground live as well

The effect would be a dead short across the supply transformer windings,bang goes yet another piece of expensive equipment
They repair the faults, change the transformer or renew the fuses and wait for the next double earth faults to do exactly the same
The supply would never survive
 
Or maybe when someones asks a question you could attempt to answer it, or just say nothing at all.

Maybe the OP is at college but trying to get a better understanding of what they are learning.

My previous post was helpful , this was just a tongue in cheek jest which the OP got.
Dont be such a drama queen.
 
Great answers to this question.

So you do not need a neutral. The neutral make it easier to handle all the different load Requirements. Earth is for safety, and dealing with unbalanced loads.

Is this correct or have I missed the point.

Many thanks
 
electricity always has to return to source. So it flows from the source (genny/battery ect), to the load. From the load it either goes to another load, (we call this wiring in series, and it causes problems), or it goes back to the source. THe reurn path is called a neutral. Electricity would not be viable without it.
An "earth cable " in laymansd terms is a shortcut back to the source, thaty means in the event of a short circuit between live and any metalwork (which we connect to the earth wire), the trip switch (MCB), or fuse will operate. If we used the neutral wire for this, then it can cause problems, and a shock hazard.
 
Great answers to this question.

So you do not need a neutral. The neutral make it easier to handle all the different load Requirements. Earth is for safety, and dealing with unbalanced loads.

Is this correct or have I missed the point.

Many thanks

Missed the point, you do not need to reference neutral to earth and as such set it at 0V to earth but we do it for good design and safety reasons. If you think of the neutral as the load return path, that may help, it is anything but neutral in what i does and what it contains
 

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