250 reference

[travis301]

Where in 250 does it specifically say you can only bond the grounded conductor and GEC once and only once ,barring exc?

 

[dereckbc]

Start with 250.24(5)

 

[George Stolz]

Where in 250 does it specifically say you can only bond the grounded conductor and GEC once and only once ,barring exc?

To elaborate a little, the code does not prohibit connecting to multiple Grounding Electrode Conductors at various points in the service leading up to the service disconnect.

So, you could have a GEC hop out of a meter socket to a ground rod, and then install a offset nipple to a service disconnect and run a GEC to a concrete encased electrode out of that.

If you intended to ask where the code prohibits Equipment Grounding Conductors and grounded conductors to touch after the service disconnect, then see the section Dereck cited. To see prohibitions from using the grounded conductor in place of an EGC, see 250.142.

 

[travis301]

Im going to look where Dereck cited when I get to work tomorrow. I know it can be done only one time at the service,but what I couldnt find today at quitting time was where the code specifically talks about the bonding of the nuetral to the grounding electrode conductor.We are hashing out a gen-set install with a solidly tied nuet to the building power(not a SDS).
On another note,can anybody see a reason to install ground rod at gen-set if it is not a SDS,and you are using a conductor back to the XFER switch for your eq. grounding conductor? It wouldnt be a seperate structure would it?

 

[Bea]

Your question is some what vague but something to consider is if your grounding electrodes that are present at a structure are bonded together and the GEC to them is taken to the service disconnect. Then you also run GEC from one of them to the meter and it is bonded to the grounded conductor. This could be considered a parallel conductor to the grounded conductor and may not meet the requirement of 310.4.

 

[dereckbc]

Travis,
Since the neutral is not switched (non-SDS), there is no requirement for a ground rod at the genset, but is permitted if you wish to install one. If you do install one, you would not bond the neutral at the generator, that is done inside at the disconnecting means.

 

[George Stolz]

Travis, I can see no reason to install a ground rod at a generator.

If you were to install one to pass the time or what have you , then it would need to comply with 250.54, and be connected to the equipment grounding conductor at the generator.