explaining the purpose of neutral wire?

The peak voltage between 0v (Neutral) and the top of the sine wave will be +340v,
would 0v not be mid point between line and (tagged)neutral ?

matt
Nope, 0v and neutral are essentially the same. If you put a scope on a bog standard AC supply the sine wave will oscillate around 0v.
Don't try connecting a scope to 240v unless it is rated for it tho - it'll go up in smoke!
 
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here goes.....say if i touched a phase with a screwdriver its going to blow right even tho the driver is insulated,
No - not unless you also touch the electrically continuous part of the screwdriver to something at a different potential to the phase, and the difference in potential was large enough for the current that would flow in the screwdriver to cause it to "blow".

Or if the PD between the phase conductor and you was large enough to break down the insulation of the screwdriver. Or the air.


isn't it in theory just like adding more cable to the circuit?well at least if it was a copper driver :D
The type of metal is irrelevant. (Assuming it's what most non-chemists would call "metal"). And unless it connects to a point at a different potential it's not being added to the circuit.


sorry if this seems stupid again but been thinking about it all day lol,what causes the surge of current,
What surge in current?


is it because the resistance is higher in the driver? :D
I=V/R
 
ok but if the voltage on the conductor is 240v isn't the driver 0v so that would be a PD? probably seems silly to u but im trying to understand it totally :D

and by saying surge i was meaning when a short circuit occurs and trips the mcb say,the current has increased to do this yeah?this is because the resistance has increased(sorry decreased i meant :D) raising the current =ohms law?
 
no the driver is at whatever it wants to be..

it's not at 0 unless you are touching the metal and are barefoot or leaning on the radiator or the back of your hand is toughing the metal CU cover etc.. ( ie unless YOU are earthed.. )

and yes, your idea of what a short does is accurate..
 
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unreal that such a 'simple' question spurred such activity :D

nearly 80 replies so far and over 1800 views lol :D
 
Work out what happens when you place the tip of one of these neon screwdrivers on the live wire, and your finger on the other end. Not interested in the rights or wrongs, just the physics.
 
The peak voltage between 0v (Neutral) and the top of the sine wave will be +340v,
would 0v not be mid point between line and (tagged)neutral ?

matt
Nope, 0v and neutral are essentially the same. If you put a scope on a bog standard AC supply the sine wave will oscillate around 0v.
Don't try connecting a scope to 240v unless it is rated for it tho - it'll go up in smoke!

no thats not what I mean
if you forget about neutral for a minute (which is why I said tagged) and take it for what it is ie one of the two opposite ends of a winding in a generator
no potential difference (0v) is mid cycle
the connection termed neutral is only 0v with reference to itself or something on its same potential
there is always potential difference between the two sides of the windings as long as the generator is turning apart from mid cycle when the magnetic field is at 180 degrees to the winding where nothing is induced ie zero volts

matt
 
left shoulderblade? off center a bit?
any tingling sensation in your left arm?
that's a heart attack that is.. go to the ER and get it checked..
Thanks ColJack - it's actually RH blade, with no tingling but some referred pain down the arm.

I went to the GP yesterday and he confirmed it as a muscle pull with a knock-on effect to everything around it.

I got an upgrade from Ibuprofen (does nothing to me) to Diclofenac - terrific stuff. Today is much better than yesterday. I can now use the mouse without having to scrumple my face up.
 
hey goldberg how is your font so small? hope your ok and not fading away! its just done my eyes in trying to read it

matt
 
the connection termed neutral is only 0v with reference to itself or something on its same potential
I take it you are talking about floating systems (electrically separate)?
Neutral needs to be at about 0v with respect to earth, otherwise it isn't a neutral. In floating systems you effectively have two phases.
 
ok but if the voltage on the conductor is 240v isn't the driver 0v so that would be a PD? probably seems silly to u but im trying to understand it totally :D

and by saying surge i was meaning when a short circuit occurs and trips the mcb say,the current has increased to do this yeah?this is because the resistance has increased(sorry decreased i meant :D) raising the current =ohms law?

I think you are trying to take this too far. The inductance and capacitance of a screw driver is such that for any practical purpose no current will flow as they are connected to a live circuit when the user is holding it by the insulated handle.

In the same way referring to peak to peak voltage is also pointless as unless one rectified and feed a capacitance one could not get both at the same instant of time.

The question was why is neutral not at earth potential and the simple answer is there is resistance between where measured and where they are bonded together so once current flows through neutral cable then multiplying the current by the resistance will give one a voltage.

Simple ohms law V = I x R

The guy is obviously not well educated in electrical systems to be asking the question and to answer with anything but simple terms will only confuse and there is not really difference between a DC or AC system as far as this question goes.

Simple resistance in cable times the current flowing produces a voltage difference and there is current in neutral cable and non in the earth cable (we hope) so there will be a voltage differential between the two.
 

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