Grounding rod conductor dimensions for 200amp service
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Grounding rod conductor dimensions for 200amp service
Hi,
I'm trying to understand Section 250.66 of the NEC 2014 (National Electrical Code) document for how to connect the ground of an electrical service to the electrode system.
So basically it says in Table 250.66 if I'm using 4/0 Aluminum wire to supply my 200Amp service and there is is a feeder between the Service Disconnect and the Breaker Panel that is 20 feet away (i'm using my case for an example), then the ground conductor in that bundle needs to be AWG #2 size (aluminum).
If I'm connecting the Service Disconnect panel ground bus to a grounding electrode system (ground rod or grounded metal water main), then that conductor never has to be thicker than AWG #6 Copper per 250.66.A.
Am I understanding this right?
I'm trying to understand Section 250.66 of the NEC 2014 (National Electrical Code) document for how to connect the ground of an electrical service to the electrode system.
So basically it says in Table 250.66 if I'm using 4/0 Aluminum wire to supply my 200Amp service and there is is a feeder between the Service Disconnect and the Breaker Panel that is 20 feet away (i'm using my case for an example), then the ground conductor in that bundle needs to be AWG #2 size (aluminum).
If I'm connecting the Service Disconnect panel ground bus to a grounding electrode system (ground rod or grounded metal water main), then that conductor never has to be thicker than AWG #6 Copper per 250.66.A.
Am I understanding this right?
Last edited by zootjeff; 11-30-14 at 09:21 AM. Reason: typo
#3
If I'm connecting the Service Disconnect panel ground bus to a grounding electrode system (ground rod or grounded metal water main), then that conductor never has to be thicker than AWG #6 Copper per 250.66.A.
#5
If you are using something like SER cable between panels the grounding conductor should be the correct size.
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Here is what I'm proposing. Do I need a separate ground connection to the Breaker Panel (which would create a ground loop) or is the ground in the wire bundle sufficient for grounding the Breaker Panel?
#7
You need the 4 wire feeder, but there will not be a ground rod at the second panel.
Last edited by pcboss; 11-30-14 at 01:51 PM.
#8
You might need two ground rods at your meter/main depending on your local requirements as this is your main service.
The ground wire should go to one of the ground bars in the 200 amp panel, not to the neutral bar, since they are available. I never recommend removing the factory strap because it will cut your neutral holes in half.
While you do not need a ground rod at the 200 amp panel, you can add one if you want, I would still bond your water service to the house panels ground bar.
Check to make sure you are wiring to the LINE side of the meter, which in most cases is on the top of the meter. Also, check that the meter/main panel is approved by your local power company.
The ground wire should go to one of the ground bars in the 200 amp panel, not to the neutral bar, since they are available. I never recommend removing the factory strap because it will cut your neutral holes in half.
While you do not need a ground rod at the 200 amp panel, you can add one if you want, I would still bond your water service to the house panels ground bar.
Check to make sure you are wiring to the LINE side of the meter, which in most cases is on the top of the meter. Also, check that the meter/main panel is approved by your local power company.
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Is this the SER wire you are talking about between the Meter Main and the Breaker Panel?
http://platt.com/pl/4A3SERGX500
This is (3 insulated) 4/0 and (1 bare stranded) 2/0.
Am I correct in interpreting the NEC in that I only need #2 AWG for the ground, but they don't really make a SER cable with 4/0 and #2 Aluminum so I just get the 4/0-4/0-4/0-2/0 bundle?
-Jeff
http://platt.com/pl/4A3SERGX500
This is (3 insulated) 4/0 and (1 bare stranded) 2/0.
Am I correct in interpreting the NEC in that I only need #2 AWG for the ground, but they don't really make a SER cable with 4/0 and #2 Aluminum so I just get the 4/0-4/0-4/0-2/0 bundle?
-Jeff
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The ground wire should go to one of the ground bars in the 200 amp panel, not to the neutral bar, since they are available. I never recommend removing the factory strap because it will cut your neutral holes in half.
There are ~30 connections for each isolated bus bar, so I either do this, or I double up in some of them if I fill the panel to 40 circuits.. Since I will likely have quite a few ganged breakers, It's unlikely I'll use all 40 of them for neutral and ground connections..
Seems like that makes a lot of sense because the Romex would have to route all the way around the breaker section if I try to do it like I've drawn... I'll update the drawing..
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Use this for connecting the #2 AL to the ground bar:
Table 250.66 of the 2014 NEC seems to indicate that I need #2 AWG, but doesn't look like they make it.. Am I missing something? Do you just split it into a few sets of strands, or do you just cut off the excess to an equivalent #2 out of the 2/0?
#18
Do you just split it into a few sets of strands, or do you just cut off the excess to an equivalent #2 out of the 2/0?
Examples: http://www.homedepot.com/catalog/pdf...cfe1ab0987.pdf