# Grounding of three different main disco's



## Gamit (Dec 30, 2009)

I installing a 200 Amp service which will have three meters and obviosly three main disconnects. One will be a 100 Amp and the other 2 will be 60's (small Apartments) I was told that I could bring all the grounding to the largest disconect and do not need to bring it to the others because it has the largest potential? I was under the impression that they all needed to be grounded. Can someone maybe point me to the right article in 250 that shows the correct answer?


----------



## Magnettica (Jan 23, 2007)

Gamit said:


> I installing a 200 Amp service which will have three meters and obviosly three main disconnects. One will be a 100 Amp and the other 2 will be 60's (small Apartments) I was told that I could bring all the grounding to the largest disconect and do not need to bring it to the others because it has the largest potential? I was under the impression that they all needed to be grounded. Can someone maybe point me to the right article in 250 that shows the correct answer?


Whatchu talkin' bout Willis! :laughing:

Each grounded conductor must be brought to each service disconnect. 250.24(C)

Whoever told you anything about the "largest potential" does not know what they're talking about.


----------



## McClary’s Electrical (Feb 21, 2009)

Magnettica said:


> Whatchu talkin' bout Willis! :laughing:
> 
> Each grounded conductor must be brought to each service disconnect. 250.24(C)
> 
> Whoever told you anything about the "largest potential" does not know what they're talking about.


 

I think he's speaking of the GEC, which could be done at the weatherhead as an option, but his setup does not sound legal. To the op, please elaborate.


----------



## Magnettica (Jan 23, 2007)

mcclary's electrical said:


> I think he's speaking of the GEC, which could be done at the weatherhead as an option, but his setup does not sound legal. To the op, please elaborate.


The GEC would also need to be bonded to each service disco.


----------



## McClary’s Electrical (Feb 21, 2009)

Magnettica said:


> The GEC would also need to be bonded to each service disco.


Got anything to back that up?


----------



## Magnettica (Jan 23, 2007)

mcclary's electrical said:


> Got anything to back that up?


What I should have said was be sure to install the MBJ in each of the disconnects.


----------



## Gamit (Dec 30, 2009)

Magnettica said:


> What I should have said was be sure to install the MBJ in each of the disconnects.


Sized in accordance with 250.122 or 250.66


----------



## Magnettica (Jan 23, 2007)

Gamit said:


> Sized in accordance with 250.122 or 250.66


The grounding electrode conductor is based on 250.66. The equipment grounding conductor is based on 250.122. Since you have a 200 amp service the GEC is #4 copper.


----------



## Gamit (Dec 30, 2009)

Magnettica said:


> The grounding electrode conductor is based on 250.66. The equipment grounding conductor is based on 250.122. Since you have a 200 amp service the GEC is #4 copper.


That's what I thought. Let me ask you one more thing? When routing my GEC through my disconnect I usually use a 3/8 squeeze connector and choke it. Is that a acceptable installation or do they sell a UL listed connector specifically designed for that application?


----------



## Dennis Alwon (May 9, 2009)

Gamit said:


> That's what I thought. Let me ask you one more thing? When routing my GEC through my disconnect I usually use a 3/8 squeeze connector and choke it. Is that a acceptable installation or do they sell a UL listed connector specifically designed for that application?


Your moderator has some nice pictures of a kenny clamp that is UL listed. I always run my wire thru the 1/4" hole in the panel


----------



## Magnettica (Jan 23, 2007)

I do the same thing, no need for any connector. Good luck.


----------



## Shockdoc (Mar 4, 2010)

You size your primary ground to your service riser and then terminate in largest Disco. Bug off and hit other two service(disco's).


----------



## Gamit (Dec 30, 2009)

Shockdoc said:


> You size your primary ground to your service riser and then terminate in largest Disco. Bug off and hit other two service(disco's).


Yes which is number 4 for 200 amps. Say I used metallic conduit and used grounding bushings. I believe you wouldn't need them if not over 250 volt and didn't use concentric. But for ****s and giggles what size conductor in my application would be used to bond the bushings?


----------



## Shockdoc (Mar 4, 2010)

Gamit said:


> Yes which is number 4 for 200 amps. Say I used metallic conduit and used grounding bushings. I believe you wouldn't need them if not over 250 volt and didn't use concentric. But for ****s and giggles what size conductor in my application would be used to bond the bushings?


#8 copper forr 100 amps, #4 for 200 amps. Some utility companies require them in the meterpan if metal raceways are utilized.


----------



## wayne g (Nov 28, 2010)

This 200 amp service calls for a #4 copper GEC, run it from the water main to the last panel terminate in that panel and come off this #4 copper GEC with bugs to pick up the other 2 panels.


----------

