GEC Tap

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A/A Fuel GTX

A/A Fuel GTX

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I have a duplex with a panel in each basement. From one of the panels, I have a GEC from the neutral bar to the water pipe and another GEC from the neutral bar to a couple of ground rods. Regarding the other panel in the adjacent basement, can I just tap the GEC that is running to the water pipe or must I tap the GEC from the ground rods also?
 
Let me get this straight--- if there is a panel in adjacent basement, am I safe to say these are not service equipment panels.
 
Dennis Alwon said:
Let me get this straight--- if there is a panel in adjacent basement, am I safe to say these are not service equipment panels.
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They are service equipment panels. There is a 2 position meter socket outside with service entrance conductors going to each side of the duplex. Each panel has a main breaker.
 
I think he is using 230.40 exception no.1 for a service to each of the units. As for the ground rods yes they would need to go to each service main.
 
Take a look at 250.64(D) and the 3 different means to connect the grounding electrode system with multiple service disconnecting means. This section was clarified for the 2008 NEC.

Chris
 
RICK NAPIER said:
As for the ground rods yes they would need to go to each service main.
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I was thinking in terms of the neutral bar in the first panel that the GEC's are terminated in would kind of be considered a grounding busbar thus allowing me to only have to run one tap to the second panel originating from the the neutral bar in the first panel.
 
According to NEC 250.64(D)(1) a common grounding electrode conductor or tap is required where there are multiple disconnecting means as per 230.40 Exception No.2 and not 230.40 Exception No.1. Does'nt seem like the code requires or even permits a common connection for two or more services even if the building has only one set of service entrance conductors. But if the services are separately derived then NEC 250.30(A)(4) would allow the two services to have a common grounding electrode conductor.
 
I think the Code precludes you from using the neutral bar in either panel as a common termination point for grounding electrodes from the other panel. I can see where you could tap the GEC going to ground rods at some point external to the panel if it is a #6 (or larger) since that's the largest required size, but in order to do so with the water pipe your "common" GEC would have to be sized to the sum main service conductor not the individual conductor to each panel.
Bottom line, GEC wire sizes might limit using 1 GEC for both panels.
 
augie47 said:
I think the Code precludes you from using the neutral bar in either panel as a common termination point for grounding electrodes from the other panel.
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Agreed. Neither panel should depend on the other, in case, say, one has to be replaced.

Kinda-sorta similar to neutrals on MWBC's not depending on device terminals for continuity.
 
Thanks Guys......Your input is always appreciated. Grounding/Bonding has to be one of the most difficult sections of the NEC to interpret.
 
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