Source Ground vs Earth Ground

Discussion in 'General Electronics Chat' started by zippoinc, Jun 18, 2011.

  1. zippoinc

    Thread Starter New Member

    Apr 4, 2011
    It would seem to me that electrons would be just as happy, if not moreso, to take earth ground over source ground when given a choice. But is this true? How does introducing an earth ground to a circuit change its behavior in relation to its voltage supply source ground?

    If an ideal ground is an essential infinite source or sink for charge that doesn't change its potential AND since we know electrons will distribute themselves for maximum separation due to their field forces and like charges, it would seem earth ground would prevail.

    And then there's this circuit, in the Worksheets section on Kirchoff's Laws. I answered the question and all, but the schematic made me think...what is that ground? Is that earth ground?


    (Oddly enough, this is essentially the same circuit I was just working out phase issues with in relation to a split-phase power source.)

    What is the consequence of removing just that "Ground" connection?
  2. Wendy


    Mar 24, 2008
    There is more than one kind of ground. They have some common roots, but it is important that they are different things.

    The one you showed is ground as defined by a low voltage battery circuit. Ground is the common point where all other voltages and signals are measured from. The symbol is for this application is the one shown. To put it another way, it is where the negative lead from the DVM goes when you are probing around the circuit.

    The other use for ground deals with high voltage AC. The common use is it is where the common point for the AC circuit is, but that is it. In the USA ground and neutral are tied together at the pole, where power is tapped via transformers from the power grid. Ground is not used to carry current, ever. It is meant as a safety feature so if the live hot wire comes in contact with earth or the metal chassis of an appliance (or drill motor or whatever) the breaker or fuse will blow, rendering the circuit dead (and not you).

    Different parts of the world have slightly different standards. What part of the world are you?