Adding a subpanel, ground issue

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Old 03-21-16, 04:42 PM
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Adding a subpanel, ground issue

I have a 200 amp service and need to run a sub panel in the same basement about 80 feet away for a tankless water heater, I have 100' of 2-2-2-4 aluminum and a 90 amp breaker along with a 100 amp box. My question pertains to the grounding.

Should the sub panel have a ground bar to the box? Does it need to be isolated from the neutral? A diagram would be great, most I see are not clear on this issue.
 
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Old 03-21-16, 04:51 PM
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Yes, the subpanel needs ground and neutral separated, thus a separate ground bar is needed. This applies to all "subpanels" including "sub-subpanels" and also "primary" panels for which there is a master disconnect switch or breaker further upstream. (Words in quotation marks are not official terms used in the NEC).

The panel should come with a neutral or ground bar fastened on with plastic brackets. Undo the green screw or ground strap to the panel body to use the bar for neutrals only.

If the panel does not have a second ground bar (may be fastened directly to the panel body) you can buy a bar for grounds which you can attach to the panel.
 
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Old 03-22-16, 09:52 AM
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As in this picture the neutral is not connected to the chassis but the green is connected to the sub panel box?
 
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Old 03-22-16, 10:08 AM
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Yes, your diagram is correct.

The neutral feed (#4 gauge or larger) into the main panelboard should be white or have a band of white tape at each end,

The neutral (#5 or smaller) between the panels must be white.
 
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Old 03-22-16, 10:12 AM
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Thank you for your help!!
 
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