Sub panel gets its own ground rod?

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the_tool_man wrote:

John The debates on this topic are endless and I won't try to settle them. I will say that the US NEC requires that every building that has an electrical supply that is more than a branch circuit must have a grounding electrode system. There are no exceptions.
What you have done so far is great. Since you have an intercom between the two buildings the code requires you to run an Equipment Grounding Conductor (EGC) with the feeder conductors which you did. All that is left to do is to connect the building disconnecting means to any grounding electrodes at the garage / shop building or in the absence of existing electrode you must install an electrode system. The point of termination of the Grounding Electrode Conductor (GEC) to the disconnecting means enclosure is usually done on the buss bar within the enclosure that is bonded to the enclosure. In a three wire feeder the bonded buss bar is the neutral buss. In a four wire feeder the bonded buss bar is the EGC buss.
So Locate the existing electrodes or install one or more new ones and connect them to the disconnecting means using an appropriately sized GEC. -- Tom H
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wrote:

This subject gets hashed around among inspectors quite a lot. It breaks down to the definition of a branch circuit. The NEC Handbook shows an illustration and a statement that a sub-panel requires an electrode connected to the ground from the main panel. You'll never be wrong to install the ground provided it is connected to the ground from the main. An individual inspector may interpret in different ways so sometimes it is easier to install it and be sure.
Dan
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Might be a can of worms, without the ground rod, you could pass. Now that you put one in you could fail till you put a second in, since now you might not meet the 25 ohm requirement.
Just saying, if you don't follow what is in black and wihite, and can interpet it to be anythign, what was the reasoning behind of writing it down in black and white. The nec chould have have been one line, Article1: Do what you feel is the max to ensure safety. End.
later,
tom @ www.BookmarkAdmin.com
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