Is my sub panel grounding correct( with diagram) ?

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  #1  
Old 01-17-21, 01:27 PM
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Is my sub panel grounding correct( with diagram) ?

My recently remodeled. The contractor did a full rewire, upgraded the main panel and installed a sub panel. Now the whole house light will flick when a big appliance turns on like refrigerator or washer machine. some time stable and sometime not. Some breakers jump randomly when I use use this or that outlet for vacuums or high pressure water gun. The contractor could not find the reason. they said maybe the PG&E( city electric supplier) line to my home may have issue? I found another electrician come to check. This electrician said the sub panel grounding is not appropriate. It should not have a 2nd ground line links to the water pipe. But the first contractor said it is correct and refuse to change. Now I need other opinion.

This is the current diagram. the main panel grounding line connects to a ground rod. but there is not a grounding light connect to sub panel. subpanel itself has a ground line connect to a water pipe. Is this a correct way? it it is not, how to fix ? ( sub panel and main panel are in the same house. no far apart).
I am in California SF area.

Thanks


current grounding diagram

how the subpanel connect to the water pipe

how the sub panel ground line connect to the case( the top entrance pipe metal) and how to connect to the grounding bar/bus. the thick copper ground wire goes to the water pipe outside the panel.

The main panel ground line connect with the neutral wire , case, and the grounding rod outside.
 

Last edited by JeanArrow; 01-17-21 at 02:33 PM.
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Old 01-17-21, 01:47 PM
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No it's not correct. Feed between panels needs to be four wires, 2 hots, 1 neutral, 1 equipment ground. Neutral is bonded at first disconnect panel and is isolated in subpanels. Second ground to pipe at subpanel is not needed. Remove ground wire from pipe at subpanel and add equipment ground wire between neutral/ground bar in first panel to ground bar in subpanel. Also typically 2 ground rods are needed linked together where your diagram shows one.
 
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Old 01-17-21, 01:49 PM
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The grounding is incorrect, but is not the source of your issue. The feed to the panel should have had a grounding conductor in it and the subpanel should not have been bonded to the case.
 
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Old 01-17-21, 01:56 PM
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The grounding is incorrect, but is not the source of your issue. The feed to the panel should have had a grounding conductor in it and the subpanel should not have been bonded to the case.
 
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Old 01-17-21, 02:00 PM
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What do you mean by subpanel should not be bonded to the case? In the diagram the neutral is misidentified as ground between panels and is not shown as being bonded at the subpanel.
 
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Old 01-17-21, 02:37 PM
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pcboss, what do you mean the subpanel grounding line should not boned to the case. I added more photo below. the grounding bus/bar itself will always connect with the case. so even we don't connect to the grounding line to the case, it has to connect to the grounding bar/bus anyway.
 
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Old 01-17-21, 03:38 PM
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Look at sticky "Sub Panel Diagrams" see picture #5 in first post.
 
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Old 01-17-21, 04:02 PM
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The thick wire from the water pipe as a grounding electrode conductor should be connected to the main panel, not the subpanel.

 
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Old 01-17-21, 04:19 PM
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I see Siemens breaker on the right side and a SQD on the left side. ?? Are the breakers all new, with lots of CAFCI units?
There is a green taped ground conductor landed on the left side ground buss. Appears to head in the direction of the meter conduit. Good.
I donít see a view of a installed, or not, breaker box neutral to ground screw.
Voltage dips not seen before might be caused by incorrectly torqued wire bolts.
Are the random breaker trips AFCI events or overload events? LED blinks on breaker should give a clue.

 
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Old 01-17-21, 04:29 PM
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1 - Did you get the electrical inspector involved?
2 - Is there continuous metal conduit between the main panel and the sub?
3 - Is the sub in a detached building or the same as the main?
 
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Old 01-17-21, 04:55 PM
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In first post the OP said the sub was in same building as the main panel.
 
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Old 01-17-21, 08:12 PM
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Thanks for point out that correct diagram.
 
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Old 01-17-21, 08:15 PM
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Hi Astuff,
1 - Did you get the electrical inspector involved?
Yes.

2 - Is there continuous metal conduit between the main panel and the sub?
No sure. there is metal conduit connect them
. but whether they are continue, I need to check.
3 - Is the sub in a detached building or the same as the main?
in same building.


Do you mean if there is the continue metal conduit connect between main and sub panel, it can be serve as the grounding line between main and sub panel because currently, the sub panel ground buss connect to the sub panel case? So I don't need to add a copper line between main and sub panel?
 

Last edited by JeanArrow; 01-17-21 at 08:31 PM.
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Old 01-18-21, 04:17 AM
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If there is a continuous metallic conduit between panels it is the grounding path and would act as the 4th conductor.
 
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Old 01-18-21, 07:10 AM
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A properly installed metal conduit between two panel enclosures, junction boxes, etc.is considered a legal and proper and sufficient bonding path, inspectors will take a quick look at it and "pass" it, and a copper grounding conductor is not needed between those two points. But I personally am skeptical of the path remaining at low resistance over decades because of oxidation where parts are joined together.
 
 

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