Bad Ufer?

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Ironically, in the OP's case, the tester which should measure the metal loop resistance is instead measuring the resistance through the UFER and back via multiple ground electrodes to the POCO neutral.
 
If you have a 3 wire and are leaving it then bond together the neutrals, grounding electrode conductor and the equipment grounding conductor
 
Bad Ufer

Bad Ufer

Thank you all for the time, interest, and information. One of the recent replies touched on old code versus new code. The house plans were approved and the main eletrical service and subpanel were installed under a 2006 premit and approved. Due to illness and other challenging events in life, it has taken me this long to finish the interior wiring and get moving again on this project--still married. Since I have a 3" pvc conduit, it may be possible to fish Ground wire of the correct size for 200 amps but I would prefer not to at this stage and arrange the grounding system to be safe at the subpanel.
 
Under 2006 permit it is likely compliant as is, except for lacking the bonding jumper. "EGC free" was allowed through 2005 NEC applications.
 
Dennis Alwon said:
That's what I get for thinking. It was done after the 2005 NEC as smart stated
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No problem... I had to look it up. I started with 2005 and missed it first time through. Only found it in 2005 after finding in both 1999 and 2002 (I knew it was in those).
 
Bad Ufer

Bad Ufer

old code versus new, plug-in tester, bond at subpanel or not. I am interested in a safe ground fault system with the 3-wire system to subpanel. I am still unclear on the plug-in tester which started this whole line of questioning. Would they work in the case of the old code subpanel allowance? Or would they indicate a bad ground? From what others have said, I likely don't have a Bad Ufer.
 
Ursahouse said:
old code versus new, plug-in tester, bond at subpanel or not. I am interested in a safe ground fault system with the 3-wire system to subpanel. I am still unclear on the plug-in tester which started this whole line of questioning. Would they work in the case of the old code subpanel allowance? Or would they indicate a bad ground? From what others have said, I likely don't have a Bad Ufer.
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If you have an actual metallic bond connection between EGC and neutral back at the panel, the plug-in tester should be perfectly happy.
When you use a three wire feeder, you have to make that bond at the subpanel end. No two ways about it, regardless of what code cycle you are or were on.

The key item that you have to get drilled into your mind at this point is that a good ground fault protection system has very little (if anything) to do with having a good earth ground.
 
Your ufer's effectiveness cannot be measured with your $12 plug-in tester. The tester's indicator color will probably change once you bond the grounding system to the neutral at the subpanel.
 
Ursahouse said:
old code versus new, plug-in tester, bond at subpanel or not. I am interested in a safe ground fault system with the 3-wire system to subpanel. I am still unclear on the plug-in tester which started this whole line of questioning. Would they work in the case of the old code subpanel allowance? Or would they indicate a bad ground? From what others have said, I likely don't have a Bad Ufer.
Click to expand...

Since you only have 3 wires you need to bond the neutral to the can and the grounding electrode conductor and equipment grounding conductor get connected on the neutral bar also, just as you would do at a new service.
 
It doesn't sound like the OP understands the difference in a grounding electrode system and grounding/bonding of equipment.
The true "safety" he is seeking occurs through the bond between the EGC (equipment grounding conductor) and the grounded (neutral ) conductor.
The bond is to assure a low resistance path for fault current back to the panel (or source) so that the OCPD (breaker or fuse) can open the circuit due to the fault.

The GEC (grounding electrode system) has nothing (very very little) to do with the operation of the electrical system, especially it's ability to clear a fault. It is to, hopefully, divert lightning to ground and high surges that would result from high voltage faults such as the high voltage lines contacting the low voltage lines.

To the OP:
Do as has been stated. If you intend to stay with the 3 wire then bond the neutral and EGC and the panel cabinet (can) together. Also connect your conductor from your uffer to the neutral bar. Do not leave the neutral isolated. The way you have it now, if there was a fault between the hot conductors and anything metal from the equipment to the panel, it would not trip the breaker. In fact it would cause a voltage potential (shock hazard) between anything grounded and any metal in the path. All the uffer, rods, plates, etc you could put in wouldn't help in that situation.
 
Bad Ufer

Bad Ufer

I seek a deeper understanding as to why the inspector advised 3 wire from service entrance to subpanel and NOT bonding (floating) the Neutral and earth grounding from the forum. I will ask him soon. Also, my initial thoughts concerning the plug-in tester were correct but I was seeking confirmation from the forum, thanks! The host has a very nice article on this subject of grounding and the code. I will post a link when i get to my desktop. I thank all those helping me understand this issue better.
 
The only explanation that I can think of for the inspector's advice is that he is trying to minimize the number of technical violations rather than looking at the safest system possible without pulling a new 4 wire feeder.
What he is not seeing is that both running three wires and bonding and running four wires and not bonding are safe and comply with different versions of the NEC, but the combination of three and no bond is just not safe.
(Four and bond is not desirable, but not nearly as unsafe.)
 
Bonding at Subpanel

Bonding at Subpanel

It is likely not impossible for me to fish the correct size Ground wire but very difficult. I would have to either use #6 Cu or possibly use a #4 with voltage drop over the 187 feet for 200 AMP service.

I will likely go with bonding at this point. The bonding bar I took out the subpanel can be reinstalled in little time.

I am still somewhat concerned with Ufer ground and lighting strikes to the house but I will rest on that issue.

Thanks for the time and the patience.
 
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