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Joined: Jul 2004
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That mile long 2 ga neutral on the pole is not going to carry all the neutral current from the primary so some of it is going through the ground no matter what. I suppose if they used delta distribution it wouldn't be an issue but they don't. I did see delta where the transformers were L/L in Maryland but never here. They had all three primary phases on the pole. Here it is one phase and a neutral.

https://gfretwell.com/electrical/Transformer%20connections.jpg


Greg Fretwell
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I have a question, existing building has a 3-wire 1Ø feeder, which was allowed when installed, a new structure was built 29 years ago that was attached to the existing structure & a Ufer was installed in the new building but never used since the existing disconnects were left alone, fast forward almost 20 years & the original part of the building was razed in order to get proper footings & a concrete floor, a Ufer was also installed, when he existing equipment was reinstalled on the new structure, would both Ufers be required to be used? There was only a few feet between both rebar stubs so they were tied together, and it's still a 3-wire feeder, although that will change that is a advantage having a oversized UG conduit.

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If the 2 Ufers were tied together in a compliant fashion, either a 30" lap for #5 (48x) or a 4ga jumper they are being used together. I would say if it was easy (AKA "available") they both need to be used but I wouldn't go to war over it..


Greg Fretwell
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Here are the rules, as I understand them:
— Each lightning target requires a ground rod ( or electrode). Exception: One multi wire branch circuit (or less) needs no such electrode;
— All grounding electrodes need to be connected into the same network; and,
— These connections may be “indirect;” that is, by using the ground wire in feeder circuits.

Some examples:
— A house with a detached garage. If the garage has but one MWBC, no grounding electrode is needed. When there is a grounding electrode, you can bond that electrode to the sub-panel you have in the garage. The green wire between the sub-panel and the house panel will suffice to “connect” the electrodes into the same network;
— The cable guy drives in a little rod of his own. You need to connect his rod to yours. You can do this directly (by running a wire from his gear to the inter system connection block) or indirectly by landing his wire on the ground buss of any convenient panel; and,
— For whatever reason, you install your two rods to opposite sides of the service. You can either run your GEC from the panel to rod #1 and then on to rod #2, or you can run separate GEC’s to the ground buss of the panel.

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Originally Posted by gfretwell
If the 2 Ufers were tied together in a compliant fashion, either a 30" lap for #5 (48x) or a 4ga jumper they are being used together. I would say if it was easy (AKA "available") they both need to be used but I wouldn't go to war over it..


The rebar stubs up a few feet away from each other, there is a continuous piece of bare copper connecting both stubs to the main disconnect, there is no overlap between the rebar in each footing as one was poured in 1993, & the other in 2011, the Ufer in the 1993 build was never used as the panels had a ground rod as the electrode & nothing was changed then, but decided to have the Ufer since the steel was being put in the footings.

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That is what the code means when it says "available". The 1993 Ufer probably should have been used all along. There is some debate about whether a stub up is a legal connection but it is pretty much universally accepted here. There have been cases where contractors had to chip up concrete to connect a Ufer. The steel in the foundation is code here.


Greg Fretwell
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Interesting scenario, NorCal.
Using my model of “one lightning target, one ground electrode,” you NEED use only one.
When Mr. Ufer invented his electrode, his goal was to ensure excellent contact between the electrode and Mother Earth. A wire within poured concrete set upon the ground provides as good contact as you’re ever likely to have.
What hasn’t been foreseen is the possibility of a building having a split foundation— which is what you describe. Trade practices would have the foundations solidly connected to each other, but those connections would not involve bonding the rebar together.
Now, for the sake of discussion, let’s consider an industrial building with an ungrounded service (no neutral). Such buildings typically have excessive bonding of the building steel and machinery to the ground electrode. This is one scenario where having such a split foundation might result in some unusual electrical problems.
Another possibility is someone later bonding to the unused Ufer. That would violate the requirement that all grounding electrodes be bonded together, possibly creating a potential difference between parts of the same building.

So, while code doesn’t explicitly require both Ufers be connected, I would consider such to be good practice.

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I can't believe that them rebar sections in that trench that form an Earthing/Grounding system aren't welded together with an Arc Welder, over here, that would fail an inspection.

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Originally Posted by renosteinke
Trumpy, that’s a very elegant solution. Alas, the exposed few inches of rod leaves an opening for some jackalope to object that the “entire” rod isn’t in direct earth contact.
That rod that you see, is the end of 3 x 6' rods welded together to effect a 0.15 ohm return path.

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I welded some rebar in a couple of my projects and the concrete guys were amazed both times. Typically steel is "continuous" if it is lapped 48x the diameter of the rod and tied with wire. In a Ufer the concrete is considered a conductor


Greg Fretwell
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