Myself have awg10 Copper wiring , a 4 wire 2 grounds 1 common ground
the other a insulated,isolated ground with its own buzz bar inside the box with its own ground , and breaker contacts are from Siemens Germany Silver over copper to eliminate oxydation , which very hard to get I tried to order more , maybe online or highly recommended changes 20 amp copper breaker every 4-5 years for copper oxydizes. And for house Siemens surge protector at the breaker box That is passive until a fault .