Zero Potential

why cant we use ground point in the place of neutral

Generally because of safety concerns as well as transmission efficiency and cost (but mostly safety).

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i was said tat the neutral is zero potential

Generally it is considered to be zero potential with reference to earth, but again this is an over simplification and depends on what electrical earthing system you are discussing (there is more than one).

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It is not consistently reliable due to weather ,excavations and a multitude of other factors.

Also it could be dangerous to persons involved in earth works .

Under normal operation faults to ground should not last for very long in a correctly installed system.

Garth, at sometime in the dim and distant past I seem to recall reading that some rural areas of Australia tried using earth return for MV systems, am I right or is my brain getting addled.

I believe that on remote distribution panels say in farms an suchlike multiple earthing at said panels was connected to the neutral. But I do not know of any earth returns of power to replace the neutral.

It would be a very dodgy way to do things.

Sorry it's just that this thread dislodged something off a shelf in the back of my mind!

Tony, it is usually referred to as SWER (Single Wire Earth Return). It is only suitable for fairly low loads, especially over long distances. It has been used in South Africa as well. See the link for the Australian & NZ (Antipodean?) experience http://www.google.com/url?sa=t&source=web&cd=6&ved=0CEkQFjAF&url=http%3A%2F%2Fsiteresources.worldbank.org%2FEXTENERGY%2FResources%2F336805-1137702984816%2F2135734-1142446048455%2FSWERIan.ppt&rct=j&q=swer&ei=BDobTqKmHIe6hAeMoumHBw&usg=AFQjCNE_cX3xl2fwfiEezRXBtDLYhwweRQ&sig2=k0oNn6a70PPxpOBF7P1cDA&cad=rja . I understand that in one instance even suitably sized steel wire was used to combat theft of the phase wire.

There is also a comprehensive article at Wikipedia.

Thanks, I thought the brain had gone AWAL.

This matter was discussed in the CR4 just a few months back, in detail. Check it up.

The basic reason is the Earth faullt protection mechanism.

Simple answer.

If the ground connection fails, someone can get electric shock.

The earth is a passive cable that is only used to first of all bond all electrical devices and also to carry any fault currents and blow a fuse.

If you use an earth as a neutral return, you have the potential to kill someone, do not use this practice.

Cheers

Joe

What you have said is not all correct and is confusing.

Zero Potential and Neutral point are not necessarily the same. It all depends on you reference frame. The Ground can be at Zero potential to the neutral if properly made, but can have a different potential than the neutral, like few volts or even the full source voltage.

The issue is very relative and needs to be takled properly depending on circuitry and some reference frame Understanding.

refer to the reply by Redfred.

I didn't say that. Please refer to the post that you replyed to.

Cheers

Joe

Maybe we are trying to say the same thing.

What I was replying to is the way you replyed to the previous...

Obviously, they are confusing the purpose of a ground return as opposed to a Neutral Wired return.Both return to a Neutral point. The Neutral point is a relative choice. In a 3 phase system it is usually the star point, but in a single phase ( like an output from a 2ndary of an isolated primary/secondary transformer), the neutral is a choice. etc.

That is all

1.In my understanding, a cable is said to be at zero potential when it is not live or when the voltage in it is zero volts.

2.Neutral wire acts as a feedback cable that completes the circuit to meet certain load requirements, hence it is connected to a neutral bar. (I stand to be corrected).

3.Earth is mainly used for surge arrestors to be directed directly to the ground, if the earth cable with stranded wires is used, but a normal cable can also be used as an earth cable provided it is connected to the earth bar.

if there are two earthing connections namely (local and remote )and if one fault happens the fault current will pass from local earthing to remote earthing so high potintial will be generated depending on the lenth between local and remote earthing . this potential will be dangerous for any thing found at that area.

In the US the nuetral is connected to ground, but also to the transformer. The nuetral is connected to the mid point of the low voltage winding giving two phase, same voltage power to the breaker panel. That's how we end up with 120VAC and 240VAC at the panel. If the neutral is not installed correctly it can cause an unbalanced load and/or a lethal hazard. The neutral is the midpoint between these two phases and you can get shocked on the neutral as well.

Sonny, you definitely put your behind down in a briar patch. And you has only your lack of thinking to blame for it. See - and I try to be simple enough to grasp - a current running out somewhere, and trying to do some work, got to get some path to return.

With me still?

In the return - as it does not do anything useful there - a low resistance is highly desired. Hence the return wire. Capiche?

The potential, high enough to fry you (to death, that is) can build up in an ungrounded system. Hence it needs grounding, not to fry you. Capiche?

Your respectful answer is greatly anticipated and appreciated.