Grounding of service

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brymegdad

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Quecreek, PA
Been awhile since I have done any large service work, was kind of thrown into this job have some questions about the grounding for the service?. The service is parallel 300MCM with a #2 ground that goes to a CT cabinet. From the CT cabinet the 300MCM goes to a trough with a 1/0 ground. There are also 3 - 200 amp main breaker panels that feed into the trough each with a #4 ground. I have a 1/0 ground that comes from water service piping and a #6 going to the ground rods.
Am I correct that I just need to land all of the 1/0?s and #4?s together in the trough.? Do I need to bond the neutral for the CT cabinet with the #2 ground for the service. Does the #6 from the ground rods need to land in each of the 200amp panels, or where? Are bonding bushings required for the 3? conduits for the 300MCM. any assistance in this matter would be greatly appricated
 
If the #4 grounding electrode conductors are connected at the first disconnect then that is all that is needed. The #6 from the rod usually goes in the CT but can be connected anywhere up to the service disconnect but if you connect it in the service disco then all 3 would need to be bonded. Easier to connect to the neutral in the trough or CT
 
Let's start with your #2. As Dennis asks in Post 2, Is it a grounded conductor (neutral) or has it been installed as an equipment ground or grounding electrode conductor.
In addition, are the #2s installed as part of POCO wiring or are they customer (contractor installed) conductors ?
We question them as they would not be properly sized for a NEC installation.

As Dennis explained, your grounding electrode conductors can connect to the grounded conductor at any point up to the disconnecting means. Most folks find it to their advantage to make this connection in the CT can or wireway rather that every disconnect.

If any of your service conductors are metallic, you must meet the provisions of 250.92. Bonding bushings are one of the methods used to meet this section of the Code, but depending on the specifics, the requirement might be met by hubs or grounding locknuts.
 
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