10-4 that is what I had installed.
my friend is a master electrician and Audiophile
you have live ,neutral and 2 grounds a common ground ,and a insulated isolated ground in its own conduit , then has its own smaller buzz bar the 20 amp
breakers are industrial silver over Copper which means like regular breakers that are copper should be replaced every 4-5 years because of oxydation,
and use gold plated Copper outlets , breakers were made by Siemens Germany
I tried getting them for my friend very hard to obtain since covid.
underwood Wally has a plug in device Puron ,buy the better ones with the Furutech
gold copper $350:, the cheaper ones $250 and 3x less conductive Brass, check them out they truly clean your line further ,even if you have a very good line conditioner.