neutral connected to ground

Discussion in 'General Electronics Chat' started by nuflia, Jan 19, 2014.

  1. nuflia

    Thread Starter New Member

    Nov 18, 2010
    10
    0
    Hi Guys,
    I know the neutral is connected to ground, and the neutral used for current returning path , i get confused for something, how can the return current does not go immediate to ground rather than completing its path through returning the power distribution system
    can any one explain this
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    USA/Canadian example: Take a common three wire tool, like a Skill Saw. All the power circuitry is connected between Line (Black) and Neutral (White). There is no Ohmic connection between the circuitry and Ground (Green). The metallic housing of the saw is connected to Green.

    If a fault (short) between Line and the case of the saw were to happen, the next time the saw gets plugged in (or the trigger gets pulled), the fault current flows to ground along the green wire, and blows the circuit breaker. If the saw is plugged into a GFI circuit, the green wire current is detected, and the GFI trips.

    Return current flowing along the white wire is ok; along the green wire is not ok.

    Now, if some idiot cuts the ground (third) prong off the Skill saw's power cord, they get what they deserve...
     
    Last edited: Jan 19, 2014
    nuflia likes this.
  3. nuflia

    Thread Starter New Member

    Nov 18, 2010
    10
    0
    Thanks for the reply,
    is the neutral connected to the ground in the main panel or it's connected in the transformer side in power grid .. this what i am trying to understand, if i have various devices , so the neutrals at all devices are not connected to the ground , there is only one point of connection where the neutral is connected to ground at the distribution panel before the main circuit breaker ???
    is this true
     
  4. 3v0

    Member

    Mar 26, 2009
    14
    3
    All neutrals and grounds come to a common point in the main panel. Or you may have all the grounds going to an ground bar and the neutrals to neutral bar with these two tied together. Both are electrically identical.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    One typical way to create the ground in the main panel (by US code) is to take an 8 foot long copper rod, pound it into the ground till it is just about completely driven in, and connect a wire to that rod back to the main panel as THE ground connection.

    Now imagine you are an electron, would you rather travel back to the power station thru a nice solid piece of wire in the transmission line, or thru the very earth itself?

    (Hint: the resistance of the wire is << then thru the dirt.)
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    In the N.A. system, any ground fault current on local equipment does not have to travel back through ground to the distribution transformer to the referenced neutral as it does in other countries as in N.A. the neutral is re-referenced to earth ground at the local service panel.
    Max.
     
Loading...