# Grounding Electrodes For Each Panel?



## scityelectric (Mar 3, 2011)

Hey Guys, I'm working on a system that contains 3 MDPs with a total of 12 SDPs, both inside and outside. I'm Being told that each panel should have its own groundnig electrodes. Could someone point me to the code article that references this? Thanks in advance.


----------



## erics37 (May 7, 2009)

scityelectric said:


> Hey Guys, I'm working on a system that contains 3 MDPs with a total of 12 SDPs, both inside and outside. I'm Being told that each panel should have its own groundnig electrodes. Could someone point me to the code article that references this? Thanks in advance.


Individual grounding electrodes? Or individual grounding electrode *conductors*? If your stuff is supplied by the same service in the same building then you have a few options concerning the grounding electrode system and GECs for multiple service enclosures; check out 250.64(D) in the 2011 NEC.

In general you'll have one common grounding electrode _system_ for the building which you can tie in to your enclosures a couple of different ways, based on the above code reference. More details on your setup would help. Is there one giant service disconnect supplying the MDPs with feeders? Or are the MDPs serving as the service disconnects? If so, how can you have 12 service disconnects and be compliant? Refresh my memory what an SDP is.


----------



## scityelectric (Mar 3, 2011)

Thaks Erics37, I dont have the 2011 code book yet, I'm still working on the 2008. Same reference? To expliain, this a millitary installation we are trying to bring up to 2008 code. I have 2 generetors switched by a manual transfer switch. From the transfer switch they have fed 3 main distribution panels. From the MDPs, each feeds 4 Sub Distribution Panels. My directive says each panel should have its own grounding electrodes. These panels are inside and outside and scattered about. I just cant find a code article to back up the directive.


----------



## RePhase277 (Feb 5, 2008)

Subpanels located within the same structure do not need a grounding electrode. Remote subs in other structures do need their own.


----------



## Wirenuting (Sep 12, 2010)

scityelectric said:


> To expliain, this a millitary installation we are trying to bring up to 2008 code. My directive says each panel should have its own grounding electrodes. These panels are inside and outside and scattered about. I just cant find a code article to back up the directive.


If your contract states a rod for each panel then you should follow the contract. 
Contact the contract Rep and be prepared to argue why it's not needed. Unless the work being performed is a hazard or safety issue you will be requires to follow the letter of the written contract. Failure to do so may cause a withholding of payment for not doing the required work. 
Sometimes there is a method to their madness and other times it's a bad write up and a contract modification must be filed. 
Good luck.


----------



## jwjrw (Jan 14, 2010)

It does sound more like a job spec. Something they want. Not required by the NEC.


----------



## Dennis Alwon (May 9, 2009)

An Nec installation would be to have the gec connected to the main service. Around here I install the GEC to the meter or the main distribution panel. If your panel has 3 main disconnects then you could run one GEC sized for the service and then tap to each service panel sized to the wire size in each panel using T250.66. For gec taps look at 250.62(D)(1)


----------



## Smoke (Feb 25, 2011)

scityelectric said:


> Thaks Erics37, I dont have the 2011 code book yet, I'm still working on the 2008. Same reference? To expliain, this a millitary installation we are trying to bring up to 2008 code. I have 2 generetors switched by a manual transfer switch. From the transfer switch they have fed 3 main distribution panels. From the MDPs, each feeds 4 Sub Distribution Panels. My directive says each panel should have its own grounding electrodes. These panels are inside and outside and scattered about. I just cant find a code article to back up the directive.


directed by whom? the specs for military installations frequently exceed the code.

btw, we have 80 ground rods spec'ed for lightning protection on my current project, we convinced them that amount was obsured and they redused it to 20.
just one example of excess...


----------



## erics37 (May 7, 2009)

scityelectric said:


> Thaks Erics37, I dont have the 2011 code book yet, I'm still working on the 2008. Same reference? To expliain, this a millitary installation we are trying to bring up to 2008 code. I have 2 generetors switched by a manual transfer switch. From the transfer switch they have fed 3 main distribution panels. From the MDPs, each feeds 4 Sub Distribution Panels. My directive says each panel should have its own grounding electrodes. These panels are inside and outside and scattered about. I just cant find a code article to back up the directive.


Your MDPs would be the place to land your grounding electrode conductors. Like others said, if your job specs state that they want grounding electrodes for each panel then there's nothing wrong with that; you can add as many electrodes to your system as you want. Not necessary per 2008 code though.

Are your generators separately derived systems or are the neutrals solidly connected to the service neutral in the transfer switch? If they are separately derived systems then there are some additional grounding electrode considerations to be aware of. Otherwise a normal grounding electrode system with appropriately sized GECs to the MDPs would be adequate; ground rods for the sub panels aren't necessary but wouldn't hurt anything. Just don't rebond the neutrals and all that normal jazz.


----------



## scityelectric (Mar 3, 2011)

They are concidering the generators as a seperatly derived system. The transfer switch is 4 pole so the neutral is disconnected with the lines. I do thank everyone involved in this discussion for their advice. I am going to use extra ground rods where ever they deem nesserary by the AHJ. Again, Thanks Guys.


----------



## Salvatoreg02 (Feb 26, 2011)

scityelectric said:


> Hey Guys, I'm working on a system that contains 3 MDPs with a total of 12 SDPs, both inside and outside. I'm Being told that each panel should have its own groundnig electrodes. Could someone point me to the code article that references this? Thanks in advance.


Did you install the egc required with all sub- panels?


----------



## scityelectric (Mar 3, 2011)

They will be installed an required.


----------



## sparky83 (Sep 26, 2010)

*spec*

It pays to read the spec book if available. I was on a job where no conduit could be strapped to the bottom of a TGI or ceiling we had to route our paths and framers ran blocking off the top of the TGI. You can argue until your blue in the face, but it doesn't fulfill your contract any faster.


----------

