Generally, outlet amps must match breaker amps. So 50A breaker -> 50A recep. 15A breaker -> 15A recep.
However, they make a special exception to allow the common-as-dirt dual 15A recep on 20A circuits.
That makes sense for two reasons:
- Many circuits (kitchen, bathroom, most commercial circuits) must be 20A.
- UL requires that common 15A receptacles have internal current pathways rated for 20A, i.e. they have 20A pass-through and can support two 10A appliances.
However, they make a special exception to allow the common-as-dirt dual 15A recep on 20A circuits.
That makes sense for two reasons:
- Many circuits (kitchen, bathroom, most commercial circuits) must be 20A.
- UL requires that common 15A receptacles have internal current pathways rated for 20A, i.e. they have 20A pass-through and can support two 10A appliances.