A (built in 1987) house that we are under contract to buy has a 30-amp sub-panel in the attached garage. The sub-panel is currently populated by two 120V, 20amp circuits for receptacles in the garage. Upon inspection, I discovered that its electrical supply is as follows:
- 30 amp breaker at main panel, with 8/3 NM-B with ground run to a box with a NEMA 10-30R dryer receptacle in the basement (yes, I'm aware that 10-30R should be replaced with a 14-30R)
- Another 8/3 NM-B with ground running from that box to the garage sub-panel
So it certainly seems that the dryer receptacle and sub-panel share the same 30-amp supply at the main panel. I know that this isn't best practice and will include it in my inspection objections, but can anyone point me to a code reference that would forbid this installation? For example, if they exist, what are the NEC sections requiring a dryer receptacle or subpanel to be on dedicated circuits?