Grounding a power panel

[Robert Huffman]

Just inspected a house built in 2004 (by a respectable builder) and saw no ground for the panel but also had no 200 amp disconnect for the panel. I suspected the disconnect was in a separate panel outside because of the distance between the meter and the inside panel and and I was correct. The 200 amp disconnect outside was grounded. Does that then mean that the panel inside did not need to be grounded?

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[Bill Kriegh]

Where is the meter? Where is the other panel? Ground mounted, mounted on another structure, mounted on the same structure?

The panel does have to be grounded. There should be 4 wires from the other panel and the neutrals isolated in the second panel.

I would hope your question involves whether or not a grounding electrode is needed on the second panel, and the answer involves where the first panel/disconnect is located.

[Robert Huffman]

220 disconnect outside by the meter on left side of house with ground running to a rod in the soil below the meter. Main panel in the middle of the house and yes, speaking about no grounding electrode for the main panel in the house.

[Dom D'Agostino]

Got a picture of the inside of this panel?

[Jerry Peck]

The remote panel needs to be grounded to the service equipment with the main service disconnect, and service equipment is grounded to the grounding electrode system (which is, hopefully in 2004, more than just a driven ground rod).

It may be easier to start from the other end (where the power come in): the utility supply is connected to an the meter; service entrance conductors connect the meter to the service equipment, which contains the main service disconnect; from there, it is common to feed a remote (downstream) panel with feeder conductors, feeder conductors will have 4 conductors (2 ungrounded 'live'/'hot' conductors; 1 groundED neutral conductor; 1 groundING conductor).

The remote (downstream) panel will be 'grounded' back to the service equipment by the 'grounding' conductor ... which is different from the "grounded conductor"/neutral.

[david shapiro]

As you know, Jerry, but possibly some reader might not, in 2004 or whenever, the inside water system, if it uses metallic pipes, needs to be bonded; and if there's 10 ft or more of underground water pipe, that could serve as the second grounding electrode if a GEC was run to the street side of the disconnect.

If the water system's plastic and the only GEC ran to a single ground rod, it could still have been kosher with fall-of-potential or other verification.