Question regarding ground wire


  #1  
Old 06-02-03, 06:08 PM
1
Member
Thread Starter
Join Date: May 2002
Location: Pittsburgh, PA
Posts: 57
Received 0 Votes on 0 Posts
Question regarding ground wire

If neutral wire and ground wire are connected to the same bar then why current is not passed to ground wire? They are all metal connection so shouldn't current passed from neutral wire to bus bar to ground wire?
 
  #2  
Old 06-02-03, 06:20 PM
J
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 8,227
Received 421 Votes on 353 Posts
If there is a problem with your neutral wire then sometimes there is current in the ground wire in the panel. This would only happen on the power company side of the neutral/ground connections. That is why you never connect the neutral and ground together after the main sirvice disconnect.
 
  #3  
Old 06-02-03, 08:21 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 1 Vote on 1 Post
Current flows from a point of higher potential to a point of lower potential. Some current does flow to ground. But because the earth has such a high resistance relative to metal, it is a very miniscule fraction of the current flowing back to the transformer through the neutral. I wish I could quantify it for you, but I'm sure the number has a bunch of zeroes after the decimal point before you get to a non-zero.
 
  #4  
Old 06-10-03, 02:59 PM
1
Member
Thread Starter
Join Date: May 2002
Location: Pittsburgh, PA
Posts: 57
Received 0 Votes on 0 Posts
More Questions

This is what my understanding of electricity.
The black (hot) wire comes from electrical company to the main circuit breaker to the individual circuit breaker. From there to my light bulb's black wire (Assuming this light bulb does not have any switch). Light Bulb's white wire is connected to the neutral wire that came from neutral/ground bus and from neutral bus current goes back to the electric company.
In the event when I accidentally touch the black wire of the light bulb, most of the current instead of passing through me will pass through bare ground wire to the bus bar and back to the electric company. Also, circuit breaker will trip.

Questions:
-------------
1. In the normal condition since all the neutral wires of my house are connected to the same metal bus bar shouldn't the current that came from my light bulb go all around to other ground and neutral wires? I understand it will not go to ground since it has the most resistance.
2. Why neutral and ground wires are needs to be grounded in the first place?
3. I know in the event of over current, circuit breaker will trip because it has magnetic strip, which will pull the switch and disconnect the black wire of light bulb from main black wire that came from the electric company. Since ground wire is never connected to the circuit breaker, in my above example how does circuit breaker know it needs to be tripped?
 
  #5  
Old 06-10-03, 04:19 PM
DaveB.inVa
Visiting Guest
Posts: n/a
==>In the event when I accidentally touch the black wire of the light bulb, most of the current instead of passing through me will pass through bare ground wire to the bus bar and back to the electric company. Also, circuit breaker will trip.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: