Electrical Wiring in the Home/service upgrade


Located in SoCal and have several questions concerning upgrading main service from 100A to 200A.  The electric utility approved either 125A service on the existing service line/main panel, or upgrading to a new line and new main panel for 200A service.

We've chosen to upgrade to 200A by installing a new 200A main service panel on the opposite side of the house fed by a new 3" Schedule 40 PVC underground conduit, and then to power the existing main as a 125A sub-panel.  Plan is to run new Sched 40 PVC 2" conduit under the house in the crawl space, then up the interior of the attached garage wall (because the garage is slab on grade), across the garage ceiling, then through a wall and through the ceiling/2nd floor of the 1/3 of the garage that was converted to living space, to arrive at the exterior wall existing main panel for conversion to 125A sub-panel.

1. Can the 2" Sched 40 PVC conduit to the sub-panel be run mounted to the drywall in the garage and behind the drywall in the room converted to living space, carrying the aluminum wire that currently runs in underground conduit to feed the original house main panel?

2. Please confirm that the new 200A main service panel requires a 5/8" grounding rod connected to both the panel ground and to the copper water main line, and that the sub-panel can have a ground wire run to it from the main panel and also be connected to the existing ground rod.

3. Planning to gut the existing 36 year old exterior in-wall 30" x 14.5" main service panel (which has survived without its cover for the past 10 years) while leaving its outer frame embedded in place in the exterior stucco, and to then insert an "interior" sub-panel into it, and then cover it with an exterior 30" x 15" shanty door from Wire Guard Systems, Inc.  Any particular issues to be aware of in this regard?

Thanks for your advice!

On #1, that is legal to do. #2 The size of the groung rod is determined by the size of the largest conductor. Using aluminum the conductor sizes are larger and you indicate using aluminum which required a 250 size and based on 250, the code requires a #2 electrode, so 5/8 is fine. #3, yes, the code requires a ground wire from the new main panel to the sub panel and also for the sub panel to be connected to a ground rod. Before any major installation, I would still check with the local electrical inspector. All of your proposals are by code, but the code is a guide book and any local authority can require more. Have this proposal written out and meet with the local inspector to ensure he will agree with the installation. Thanks J
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Electrical Wiring in the Home

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J Cook


General electrical wiring, including but not limited to, residential, panelboards, control wiring, low voltage wiring, Heating and A/C control wiring, single and three phase wiring.


I have been doing electrical since high school. I have been licensed by the State of North Carolina for ten years and am currently the Building Maintenance Superintendent for a municipality. I have extensive control wiring experience.

Refrigeration Service Engineers Society.

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