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02-18-2011, 08:18 AM   #16
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Grounding Conductor and Grounded Conductor can be somewhat confusing. A grounded conductor is a normal current carrying conductor that is earth referenced. A grounding conductor should not have current flowing in it except in a fault.
So in Stubbies clarification he is saying that the neutral bar which has the big neutral wire from the transformer - the Grounded Conductor - also has to have the Grounding Electrode Conductor connected to it. The GEC is the bare copper wire that goes to you ground rod. This makes your system earth reference.
Although it would seem to most that the ground wire should be attached to the ground bus, this is not correct.

 02-18-2011, 08:22 AM #17 Newbie   Join Date: Jan 2011 Posts: 24 Rewards Points: 10 I found this interesting an now I am more confused LOL from http://www.mikeholt.com/videodisplaynew.php?pageid=4379 "The earth is not considered an effective ground-fault current path. DANGER: Because the resistance of the earth is so high, very little current returns to the electrical supply source via the earth. If a ground rod is used as the ground-fault current path, the circuit overcurrent protection device will not open and metal parts will remain energized. For example, the maximum current flow to the power supply from a 120V ground fault to a 25Ω ground rod would only be 4.8A. Figure 250–24 I = E/R I = 120V/25Ω I = 4.8A"
 02-18-2011, 08:30 AM #18 Licensed electrician   Join Date: Sep 2007 Location: Maryland Posts: 10,861 Rewards Points: 1,876 Ground rods are for high voltage events like a lightning strike. They have nothing to do with the 3rd prong or clearing a fault. __________________ Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.

 02-18-2011, 08:39 AM #19 Newbie   Join Date: Jan 2011 Posts: 24 Rewards Points: 10 OK, so that third wire coming into the panel and connected to the neutral bus is coming from the transformer and not the ground rod in the dirt. I have no bare wires coming into the service panel or a bare wire connected to the grounding rod - this one is insulated and looks the same as the one connected to the neutral bus.
02-18-2011, 08:58 AM   #20
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Quote:
 Originally Posted by frank otero OK, so that third wire coming into the panel and connected to the neutral bus is coming from the transformer and not the ground rod in the dirt. I have no bare wires coming into the service panel or a bare wire connected to the grounding rod - this one is insulated and looks the same as the one connected to the neutral bus.
The wire from your ground rod should be connected to the same bus bar that the neutral, or Grounded Service Conductor, is attached to.
Most of the time the GEC is bare copper but there are other options.
Maybe you could post a picture of your panel.

 02-18-2011, 09:17 AM #21 Newbie   Join Date: Jan 2011 Posts: 24 Rewards Points: 10 "Maybe you could post a picture of your panel" Attached Thumbnails
 02-18-2011, 09:30 AM #22 Licensed electrician   Join Date: Sep 2007 Location: Maryland Posts: 10,861 Rewards Points: 1,876 The Z shaped copper piece shown in the last pic is your bond between the panel enclosure and the buss. I do not see a GEC like from a metallic water line or a ground rod or Ufer. __________________ Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
02-18-2011, 09:51 AM   #23

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Quote:
 Originally Posted by frank otero I found this interesting an now I am more confused LOL from http://www.mikeholt.com/videodisplaynew.php?pageid=4379 "The earth is not considered an effective ground-fault current path. DANGER: Because the resistance of the earth is so high, very little current returns to the electrical supply source via the earth. If a ground rod is used as the ground-fault current path, the circuit overcurrent protection device will not open and metal parts will remain energized. For example, the maximum current flow to the power supply from a 120V ground fault to a 25Ω ground rod would only be 4.8A. Figure 250–24 I = E/R I = 120V/25Ω I = 4.8A"
It is very common for the general public and even some electricians to confuse the 'effective ground fault path' with the earth. I think the terms grounding, grounded and ground mislead people into thinking electricty serving your home goes to earth after it comes to your home from the transformer. In reality it could care less about the earth as far as its normal operation. Electricity under normal operation always seeks a return to its source ... your poco transformer.
This complete loop if you will completes the necessary circuit to allow your appliances and lighting to work properly be it 120 volts circuits or 240 volt circuits.
In the event of a ground fault the equipment grounding conductor and all bonded metal that would likely be energized allows a low impedance/resistance path for the fault current to return to the transformer center tap over the service neutral. This allows enough current to pass thru the circuit breaker to cause it to open and clear the fault.
In Mikes example he is showing that if the fault circuit was to earth and not over the service neutral to the transformer only 4.8 amps would flow thru the circuit breaker. That is no where near enough amperage to open a 15 amp breaker let alone a larger circuit breaker.
The attached drawing is representative of an effective ground fault path that will open a circuit breaker.
Attached Thumbnails

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Stubbie

 02-18-2011, 10:11 AM #24 Member   Join Date: Nov 2010 Location: Ontario Posts: 33 Rewards Points: 25 the wire coming from your ground rod goes to the neutral bar, there is usually a spot in your panel where your serivce conductors terminate, this area is usually not accessible when you take off the cover, there is usually a separate cover for this area. your ground bar in the panel is bolted to the enclosure. There needs to be a connection from your neutral to the enclosure, this is a strap, a bonding screw(a black screw that blots your neutral bar to the enclosure) or a jumper. not sure where you are, so I don't know which code applies, always check your local rules and regs. hope this helps
 02-18-2011, 10:34 AM #25 Licensed Pro   Join Date: Mar 2007 Location: SC Posts: 1,571 Rewards Points: 1,000 It is quite possible your GEC (from the ground rod) terminates in the meter enclosure and not the service panel. Some utilities require this. __________________ "Life is hard. Life is harder when you're stupid." John Wayne
 02-18-2011, 10:49 AM #26 I=E/R     Join Date: May 2010 Location: Minnesota Posts: 2,052 Rewards Points: 1,000 We don't see the complete ground bus bar but from what I see in the picture the ground bar, the one on the right, is mounted in insulators and is not attached to the panel case. Is there anything at the top of the ground bar outside the picture that would be a connection to the case or the neutral bar?
 02-18-2011, 11:37 AM #27 UAW SKILLED TRADES     Join Date: Jan 2007 Location: Kansas Posts: 5,341 Rewards Points: 2,652 Jim Do you see anything bonding the bus with the equipment grounding to the panel ? It appears to be set on insulated standoffs but I don't see the bonding means. I see it on the neutral bus. If this is service equipment he needs that grounding bus bonded to the panel. I just got back from the eye doctor and have a new set of contacts in and not seeing to well at the moment ...eyes are dilated.... EDIT ... I see A7 has already asked as I typed. __________________ " One nice thing about the NEC articles ... you have lots of choices" Stubbie
 02-18-2011, 12:44 PM #28 Master Electrician   Join Date: Feb 2011 Location: Atlanta, GA Posts: 4 Rewards Points: 10 The NEC deals with grounding in Article 250. The majority of what you are discussing will be found in 250.50, 250.52, 250.53, 250.68, and table 250.66. Grounding is a very important part of the electrical system and it needs to be installed properly to prevent creating parallel paths to ground. This could result in a difference in potential on the ground wires and create an electrocution hazard. If you are not completely sure of your system, you may want to call a licensed electrician to verify the grounding system for your electrical service.
 02-18-2011, 03:24 PM #29 Newbie   Join Date: Jan 2011 Posts: 24 Rewards Points: 10 All this began when my gas stove's igniters started to act up (tend to spark on their on while cooking) and the manufacturer (electrolux) kept blaming the ground or lack thereof, claiming that the stove requires its own ground (although the installation does not call for that and it even allows you to ground through the neutral where permited by code). The tech (not an electrician himself) said that by code I needed four wires going into my service panel - I think we have dispelled that here. I took apart the junction box that feeds the stove - four wires - and disconnected the stove. I had continuity from the ground wire that feeds the stove to the ground bus bar and neutral bar in the service panel, and also to the rod outside. I will check with the electric company to see if the wire from the ground rod is bonded at the meter....I could cut the seal but...... Thank you very much for taking your time with my problem.
02-18-2011, 03:49 PM   #30
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Last edited by AllanJ; 02-18-2011 at 04:06 PM.

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