Depends on how it's wired in your specific coach. On mine, the radio has a switch to use either the chassis or the house circuit.
An easy way to find out which battery bank feeds the radio is to turn on the radio and disconnect the ground lead from the chassis batteries. If the radio shuts off, they feed it.
2008 Itasca Meridian 37H & 2015 Flagstaff T12RBST
2011 & 2012 Len & Pat's "One lap of America"
27K miles & 41 states in 13 months - Woo Woo
Yellowstone Lake 6-1-2012