I have a somewhat unique situation. I had a separate 200A service run to my garage a few years ago to run my welders and compressor. My house still has 60A service. I am now moving my wood shop from a commercial space into my basement and will need more power down there. I was advised by the electrician who installed the 200A panel in the garage that at some point I could pull 100A off that panel and go underground to the house. I have no problems with the existing 60A service in the house so simplest approach would seem to just install a sub-panel in the basement to feed all the woodworking machinery and leave the existing house wiring as is. I intend to run 2/2/2/4 THHN/THWN wires in conduit to feed the sub-panel.
Reading up on this I find much confusing info regarding grounding and bonding and of course it's all addressing a sub-panel from the house to the garage, not the way I'm going. So a few questions…
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Am even I allowed to have two panels in the house with separate feeds?
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Unlike most garages the house is full of 'metallic pathways' and I assume the existing 60A panel is grounded so how would one properly deal with bonding and grounding the new 100A sub-panel in the basement?
I understand the ground and neutral in the sub-panel should not be bonded but I'm confused about the grounding. Some say grounding electrode, others say the #4 equipment ground is good, some say I need an additional grounding electrode at the main panel in the garage…
Any clarification would be much appreciated.
Best Answer
If you live in an area covered by NEC, you're only option is to upgrade the service to the house.