Here is the deal. 1200 amp main with 8 200amp module meter sockets. What should the ground be? Reading the code book is confusing. One area it states size to 250.66. Then somewher else it states the groung does not need to be any larger than 6ga. There is a grounding point in the disconnect, in each meter socket, the building needs to be grounded. What is the deal?
Gounding Question
- Thread starter joebudd
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The Grounding Electrode Conductor only needs to be #6 if it is the conductor to the ground rod. All other GEC's must use T.250.66
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Let's start with the type of grounding electrode. If you're using the water pipe or building steel you would need to size the GEC according to 250.66. For a ground rod the largest size required in #6, for a CEE the largest size required is #4. You can run one GEC and tap off to each disconnect with a split bolt. Here's one example from the NECH:
So let me get this correct. If I run the ground from the disconnect to the building, the wire will need to be sized for the table 250.66. then from the building to the grounding electrode I can use a number 6ga. All meter sockets to ground electrodes can be 6ga as well. Sound right?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Sorry in my first response I missed the part about you having a 1200 amp main disconnect. Since you have a 1200 amp main you would use T250.66 to size the GEC from the 1200 amp disconnect to the electrode, if the electrode is a water pipe or building steel. If the electrode is a ground rod you only need a #6 cu GEC. If the electrode is a CEE you'll only need a #4 cu GEC.
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What does CEE stand for?
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Concrete Encased Electrode
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
As mentioned above but also known as a Ufer-- named for Bob Ufer-- google him to learn more
Dan coulstring
Member
- Location
- Maine
Bob Ufer was an announcer for a college football team. CEC was named after Herbert G. Ufer, who developed the technique during World War II in Arizona
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Thanks-- what was I thinking. :grin: I had just gotten off the phone with a guy named Bob- guess that was it.
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- Location
- Bremerton, Washington
Here is another explanation
Section 250.66 tells us the size of the GEC is based on the ungrounded conductors, not the size of the service disconnect. Then Table 250.66 tells us three cases when the GEC can be smaller, for a ground rod, for a CEE, and for a ground ring. Table 250.66 is part of Section 250.66
Section 250.66 tells us the size of the GEC is based on the ungrounded conductors, not the size of the service disconnect. Then Table 250.66 tells us three cases when the GEC can be smaller, for a ground rod, for a CEE, and for a ground ring. Table 250.66 is part of Section 250.66
weressl
Esteemed Member
We use #2AWG minimum for mechanical strength, but #6 should be OK per NEC.
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