Sub panel

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  #1  
Old 11-05-16, 09:10 PM
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Sub panel

I'm installing a sub panel about 12" from my main panel in the basement of my house. I know the grounding question has been asked 1000 times and I know it does not/cannot have a separate ground. I have 2 hots and 1 neutral (all #2 cu) and 1 ground (#6). The ground and neutral bar are not bonded. My question is kind of two parts. #1- In the main panel, the neutral and grounds are sharing the same bars. Is this ok with a sub panel? #2- in order to ground the sub panel, you have to run a screw into the box through the ground lug. If I do that, there will be continuity between the ground and neutral due to the grounds and neutrals being tied together in the main panel. Does this tie back in to my question #1?
 
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Old 11-05-16, 09:26 PM
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I'm installing a sub panel about 12" from my main panel in the basement of my house. I know the grounding question has been asked 1000 times and I know it does not/cannot have a separate ground.
Wrong if you mean EGC (Equipment Grounding Conductor). There must be an EGC. It must have an isolated (not bonded) neutral bar and a separate bonded ground bar that the EGC goes to*. Maybe your thinking of the GEC, Ground Electrode Conductor AKA ground rod. If so you are correct no ground rod is needed.
In the main panel, the neutral and grounds are sharing the same bars. Is this ok
If it contains the first breaker or fuse after the meter, yes. It is required by code and the neutral/ground bar must be bonded.

Note panels almost never come with ground bars so you will need to buy and install one. Some panels come with two neutral bars. Don't confuse the second neutral bar with a ground bar. It isn't intended as a ground bar.

*Note: If the main panel and subpanel are not connected by metal conduit you must run a ground wire of appropriate size to the subpanel ground bar.
 

Last edited by ray2047; 11-05-16 at 09:42 PM.
  #3  
Old 11-06-16, 05:46 AM
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You do need specific bonding from the subpanel ground to the main panel ground.

After all is said and done you will have continuity between neutral and ground as measured at the subpanel. It is just that current, in order to get between neutral and ground at the subpanel, must go to the main panel to get across. The safety is that even under practically all abnormal conditions, no current is going to make that particular journey or routing for the purpose of electrocuting someone. You still have the benefit that, if an equipment defect results in a fault to ground, any abnormal current will escalate so as to quickly trip a breaker and, under normal conditions, the ground wire (equipment grounding conductor) will not carry any current.
 

Last edited by AllanJ; 11-06-16 at 06:12 AM.
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