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I just realized that my last post was in November 2009!!! It has been 8 months since I last blogged..haha. Spiderwebs here and there. =P

Today out-of-the-blue, we are going to talk about Electrical Engineering! I noticed I have not actually written anything useful/constructive yet in my blog(haha), but this shall be a start.

My colleagues and I were discussing something over tea time lately and one interesting topic was "What's the difference between Neutral and Ground"? It seems quite simple at first but later on each of us had different understanding on the topic. So here I am, presenting to you MY UNDERSTANDING on this topic(it might be totally wrong..shitz) and would like to invite fellow engineers/muggles to give your two cents.

Please follow the picture sequence below(I hand sketched wan!):


Imagine the power generated in the power plant(somewhere out there) as an AA battery. To distribute this electricity to us, logically it would require two transmission lines, i.e. to complete the circuit. However, this method(two long cables) might be a bit expensive.


So some wise guy thought, "Why don't we use the ground/earth as the conductor for the return path?" Maybe after some study and experiments it is proven that ground is a good conductor, thus the above concept was born(neutral point of the generator is earthed). Minus one cable..cool!


When the transmission lines reach distribution transformers, there will be a delta-to-star transformation of the power and here, the star/neutral point of the transformer is earthed. From here on, we will start the Neutral lines and L-N lines will go to our homes. (Notice oh, when transmission time only Live lines, but distribution time have Live and Neutral lines d.)


If we look at the power socket in our homes(for Commonwealth countries), on the bottom-right would be the L and bottom-left is N. On the top-centre is Earth which is actually connected to a metal rod planted below the ground of our home. In normal cases, the current will flow from L to some load in our home and back to N. However, if there is a leakage(say the Live supply is suddenly shorted to the body/casing of the appliances), luckily the body is connected to Earth already so there would be an alternative path for the current to flow to..NOT THROUGH THE HUMAN BODY..phheewww! In any case, there are always MCB, ELCB/RCCB to protect us.

So in conclusion(on the difference between Neutral and Ground/Earth):
1.1 From the Generation side, the Neutral and Earth have the same common point.
1.2 Neutral/Earth is this case would act as the return path of the supply.
2.1 From the Distribution side, we start to run the Neutral lines.
2.2 Neutral in this case would be the return path of the supply.
2.3 Earth is still available but normally there will be no current flowing, only during supply leakage.

DONE.

Till we meet again(maybe 8 months from now), ardios!

Rgds,
-Quan-

p/s: I might be completely WRONG so if you know, please correct me. Thanks!

;;