Ron Amedee Posted May 23, 2011 Share Posted May 23, 2011 David read the post agin...The nuetral needs to float and the ground be on the box. Link to comment Share on other sites More sharing options...
David Rise Posted May 23, 2011 Share Posted May 23, 2011 Ron Amedee wrote:David read the post agin...The nuetral needs to float and the ground be on the box.Here's a pic with the grounding bar installed on the lower left and the ground from the plug going to it. Of course, I'll move the outlet grounds to the bar. Attached files Link to comment Share on other sites More sharing options...
David Rise Posted May 23, 2011 Share Posted May 23, 2011 Awesome....I think we have a winner! Link to comment Share on other sites More sharing options...
Ron Amedee Posted May 23, 2011 Share Posted May 23, 2011 Now when you place it where you need to..Add a ground rod to the ground bar and your good to go !!!! Link to comment Share on other sites More sharing options...
David Rise Posted May 23, 2011 Share Posted May 23, 2011 Welcome Jeff and Thanks again. Good luck on your CCR's.I'll post a completed picture after I move the grounds and everyone will have a legal panel to go by. Link to comment Share on other sites More sharing options...
Ron Amedee Posted May 23, 2011 Share Posted May 23, 2011 Jeff it is easy when you did such a great job of explaining !!! Long live the Do it your selfer's...with a little help!!!! Link to comment Share on other sites More sharing options...
steve synek Posted May 23, 2011 Share Posted May 23, 2011 Jeff...........nice job coach!!!!! I could not have handled that as well.Steve Link to comment Share on other sites More sharing options...
steve synek Posted May 23, 2011 Share Posted May 23, 2011 Steven wrote: David Rise wrote: Seems to me that I can just ground the box? Just curious.So back to Dave's question here: An old breaker panel in an old house is failing and needs to be replaced. There is a conduit that leads from the box with the meter and master 100A breaker to the panel, about 25 feet away.The panel was installed in the late 1060's. It has a single neutral/ground bar that is tied to the white wire from the conduit. The conduit has only 3 wires. All circuit ground and neutrals are attached to the same bar.This panel is to be replaced with a modern panel that has a separate ground bar (tied to the case). The question, which I think is the same as David's, is what to attached to this ground bar?From what I am hearing, it is not up to code (and a bad idea) to just use the neutral bar, like they did in the late 1960's in the old panel.The 2nd option is to assume that the metal conduit will provide sufficient grounding, but this is a big unknown. We do know that there is a 10-gauge wire from a water pipe to somewhere in the meter/main breaker panel.The 3rd option is to run a separate ground wire from the ground bar to a water pipe, about 25 feet away. This seems the best. What gauge would be best? Since all circuits that use ground (the oven and dryer don't) are less that 30A, would a 10-gauge ground wire be a good choice?StevenAs I understand your situation, there is a main disconnect at the meter and you are talking about a sub panel replacement. It needs to be feed with two hots, a grounded conductor (white) and a grounding means. The grounding means can be the conduit if it is continuous. The grounded (white) conductors and the green or bare conductors need to be separated at the sub panel. You are not permitted to use a water line as the grounding means at the sub panel. The grounding means has to originate at the main electrical disconnecting means (the only place grounded and grounding conductors are bonded together.) To clarify something Jeff said, the electric code does not give a distance from the meter to the first disconnecting means. It says something like....."nearest the point of entrance" some areas take that to mean 5 ft......some say 25 ft so I've heard. If the wiring is on the outside of the house, there is no limit between the meter and the main panel.The "green" wire is sized by the circuit feeding the sub panel. If you tell me what size breaker or fuse turns off the sub panel at the source, I can tell you the correct size green or bare conductor to use.As an inspector, I have run into situations like this. The best case is to verify a grounding path back to the main disconnect as required by today's code. I have made the call where the feeder to the replacement sub panel is not replaced, to allow the bonding of the neutral and grounding conductors together at the sub panel ( this is how it was done for years and in Ohio old work is grandfathered).To summarize, 4 wire makes the best sense. Do not guess on the conduit as a continuous path- make sure it makes a continuous bond. Do not make a water pipe connection for a grounding path.Steve Link to comment Share on other sites More sharing options...
Steven Posted May 24, 2011 Share Posted May 24, 2011 First, I want to thank you for all the information, "Straight from the horse's mouth." Now I hope you don't mind answering some additional questions I have.steve synek wrote: As I understand your situation, there is a main disconnect at the meter and you are talking about a sub panel replacement. I'm not sure of some of these terms. There is a panel on the outside wall of the house that has the meter and a 100A breaker (2 pole). This is clearly the main breaker, but I'm not sure if this is called the main panel or simply the disconnect. I'll call it the disconnect.There is a 25-foot conduit that connects from the disconnect to a panel inside the garage that feeds the whole house. I'm not sure if this is called the main panel or a sub panel, but I'll just call it the panel.The panels are Zinsco panels. Google Zinsco to learn why the panel is being replaced.It needs to be feed with two hots, a grounded conductor (white) and a grounding means. The grounding means can be the conduit if it is continuous. The grounded (white) conductors and the green or bare conductors need to be separated at the sub panel. The conduit has two hots and a white. It is constructed in pieces that are held together with set screws. I'm not sure if this means continuous. It goes through finished walls so it can't be replaced, and it would be very difficult at this point to pull an additional green wire through.You are not permitted to use a water line as the grounding means at the sub panel.Can you help me understand the reason for that restriction? Is it because water lines are usually unreliable grounds?The disconnect is grounded with a #10(!), white(!) wire that runs along the top of the garage walls from the meter panel to the water pipe. Can I tie into this wire? Can I run a new wire along side it and ground to the same point?The "green" wire is sized by the circuit feeding the sub panel. If you tell me what size breaker or fuse turns off the sub panel at the source, I can tell you the correct size green or bare conductor to use. As I mentioned above, the old work feeds the panel with 3 wires and a 100A breaker, and the meter/disconnect panel itself is grounded with a #10 wire. Link to comment Share on other sites More sharing options...
steve synek Posted May 24, 2011 Share Posted May 24, 2011 Steven wrote: First, I want to thank you for all the information, "Straight from the horse's mouth." Now I hope you don't mind answering some additional questions I have.steve synek wrote: As I understand your situation, there is a main disconnect at the meter and you are talking about a sub panel replacement. I'm not sure of some of these terms. There is a panel on the outside wall of the house that has the meter and a 100A breaker (2 pole). This is clearly the main breaker, but I'm not sure if this is called the main panel or simply the disconnect. I'll call it the disconnect.There is a 25-foot conduit that connects from the disconnect to a panel inside the garage that feeds the whole house. I'm not sure if this is called the main panel or a sub panel, but I'll just call it the panel.The panels are Zinsco panels. Google Zinsco to learn why the panel is being replaced.It needs to be feed with two hots, a grounded conductor (white) and a grounding means. The grounding means can be the conduit if it is continuous. The grounded (white) conductors and the green or bare conductors need to be separated at the sub panel. The conduit has two hots and a white. It is constructed in pieces that are held together with set screws. I'm not sure if this means continuous. It goes through finished walls so it can't be replaced, and it would be very difficult at this point to pull an additional green wire through.You are not permitted to use a water line as the grounding means at the sub panel.Can you help me understand the reason for that restriction? Is it because water lines are usually unreliable grounds?The disconnect is grounded with a #10(!), white(!) wire that runs along the top of the garage walls from the meter panel to the water pipe. Can I tie into this wire? Can I run a new wire along side it and ground to the same point?The "green" wire is sized by the circuit feeding the sub panel. If you tell me what size breaker or fuse turns off the sub panel at the source, I can tell you the correct size green or bare conductor to use. As I mentioned above, the old work feeds the panel with 3 wires and a 100A breaker, and the meter/disconnect panel itself is grounded with a #10 wire.Steven First off, I'm not smart enough to figure out how to reply section by section to quotes like you did. (First disclaimer- most of what I talk about is required as part of new construction requirements- I would recommend you talk to the local Authority in Charge for there interpretation of where new and old begin and end).The breaker at the meter is your main disconnect and service over-current means. That is the only location that White and green (or bare) wires can be connected together. I would define the panel you are replacing as a sub panel. If you were to provide a green wire from main disconnect to subpanel, it would have to be a minimum #8 copper conductor (sized by the 100 amp service breaker that protects the sub panel. ) The primary purpose of the green (grounding conductor) is to provide a low impedance path to the source to facilitate the tripping of the over-current device (breakers or fusses) should a fault occur. It sounds like the conduit is EMT as set screws are the typical connectors. If there were someway to make sure the conduit is continuous, this could be used as the grounding path for 100 amps. The code requires the grounding path to be provided with the power conductors. In the old days, the water line could be used for grounding, but in recent years, the proliferation of non metallic waterlines has caused the elimination of using a water line as a grounding path. Persons were repairing/ replacing copper with plastic (PEX)and loss of the grounding path would occur. ( The typical grounding electrode conductor connections is still required to the water service line at the water line entrance and to ground rods which have little to do with interior wiring (IMHO). These connections are required to combat the effects of lightning and surges on the power lines (typically caused by crossed utility lines as in storm events). Hence ground rod connections and water lines connections to the electrical equipment is at the meter or first disconnecting means. You don't want to bring lightning or surges into your wiring system. I don't want to write a novel, so I won't get into bonding interior conductive materials likely to become energized!) As you describe a #10 running to the water line, I believe this to be the grounding electrode conductor. By today's code, it should be a minimum #6 copper if not run in a raceway(smaller than #6 requires protection from damage).The above is brief summary of what I believe the code requires and is not meant to be a complete list of all the requirements or possible exceptions. Currently I am responsible for enforcing the 2008 NEC. When in doubt, contact that licensed electrician or local inspector.I would be more than happy to answer any more questions.Steve Link to comment Share on other sites More sharing options...
Steven Posted May 25, 2011 Share Posted May 25, 2011 I just wrote instructions on how to multi-quote posts, but there must have been a bug that eliminated my whole post! That just shows that I'm not as smart as some of my posts appear. Anyway, thanks for the information. And I just figured out why you shouldn't use water pipes as ground. Let's say the sub panel is in the laundry room and you use a water pipe for ground. Everything is fine until the plumber installs a water softener with a plastic bypass valve. Link to comment Share on other sites More sharing options...
KStatefan Posted August 16, 2011 Share Posted August 16, 2011 Jeff Millard wrote: Here's a good illustration of why it's not a good idea to bond the neutral and ground together in a sub panel. What it doesn't explain is why you also don't want the ground bonded to the case of the subpanel. In this picture you can see that the grounds become a normal path for current to flow in nearly equal amounts. If, in addition to this, the ground is bonded to the subpanel case, there will be a difference of potential between the case and earth when the panel is under load. That is just plain deadly....JeffThis image was borrowed from the ICC Bulletin Board.Did this image get removed? I can not see it. Link to comment Share on other sites More sharing options...
David Rise Posted August 16, 2011 Share Posted August 16, 2011 I can't see certain images from my work computer. Not sure why that is, but I can see them all fine from home.Either the network here, or Windows XP at work vs. Vista at home.AND....I can't see any of the 2010 light shows, thanks to the mp4 format. Link to comment Share on other sites More sharing options...
Bernie Posted August 20, 2011 Share Posted August 20, 2011 Link to comment Share on other sites More sharing options...
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