I live in Medina County, Ohio, USA.
This other question discusses a bit about running two load centers from a meter. I am wanting to do exactly that. I currently have service that supports 200amp (confirmed with city). My existing disconnect in garage is 100amp and has a 3 wire cable going to 100amp panel in the house. That cable is routed through difficult places and the electrician tells me it will be expensive to upgrade to the 4-wire cable that would support 200amp.
I really only need 100amp more for the garage, so I did a little research and it appears that I would be able to run another 100amp loadcenter off the meter. The other Stack Exchange question I linked to above discusses that, even going over some code (like you can do this because of an exception if the disconnects are grouped together).
So in order to avoid having to upgrade the whole house to 200amp and replace that cable, which increases the cost drastically, I'd like the electrician to run another loadcenter right off the meter and have it right next to the existing disconnect in the garage. I mentioned this to him and he said we'd still need to replace the cable. Before I go back and forth with him, I'd like to be more informed, which is what I'm trying to do here.
First, is running a second loadcenter code-compliant? The total amps allowed by the two loadcenters would be 200amp, and the meter supports 200amp. The existing disconnect and the new loadcenter would be physically right next to each other.
Second, if that is code-compliant, would the existing 3-wire cable between the existing disconnect and the house panel need to be upgraded? If so, why? It would never have more than 100amp (protected by the disconnect breaker).
Third, is there anything special that would need to be done to run a second loadcenter or is it just run in parallel from the meter?
See my professional diagram below.
Thanks for your help, Mike