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Understanding Ground

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lawOf3

New Member
I am somewhat new to the field of electricity and am interested in deepeniong my understanding the concept of Ground. I find it a quite mysterious and elusive subject, particularly when it is related to (used as) a negative terminal and/or the "neutral wire".

Physically (wire connetced to chasis, or pole driven into the Earth) I get it, but how does it work and why is it necessary in circuits?

I understand that this could require a lengthy responce. If that's too much trouble maybe someone could just point me to some reference materials that address the subject. It's not very well covered in most beginning electronics books.

Thanks.
 

stevez

Active Member
I tell you what I understand which is based on electrical safety. As electrical systems developed thru the late 1800s & 1900's a lot of experience was gained with different systems. Much of that experience also included serious injury or death.

One leg of a distribution system is grounded so that if the other leg comes in contact with ground it will blow the fuse or otherwise interrupt the circuit. For multiphase systems it helps anchor the voltage to a comon point maintaining balance in systems.

I am sure that if you follow the development of the NEC, National Electric Code which is part of National Fire Protection Association or NFPA, you can read about what lead to this evolution.
 

Klaus

New Member
" but how does it work and why is it necessary in circuits?"

Look at circuit ground that way; there are many signals and different voltages to be found in a complex electronic circuit. They all require to have a common reference point to make sense. That reference point is conveniently the ground connection.
It does not *have* to be ground but, since 0V is usually the common rail for the voltages, tying it to ground (chassis, shield, earth) gives a safety factor. If any of the voltage carrying wires would accidentally come loose and touch a grounded metal part, a fuse would blow and prevent further damage (fire, etc.).
Tying the signal return connection also to ground does eliminate a great deal of radiated interferance that could otherwise be picked up by floating signal lines. This part is difficult to explain, I'm sure if you search a little on the net you will find good tutorials on this subject. I't quite a bit more complex than it looks at a first glance.

Steve pointed out the reasons for using actual ground (earth) connections with power distribution systems.

Klaus
 
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