Considering 5-20p duplex receptacle, if I break the tab, can both receptacles supply 20 amps?


Yes. The outlet configuration - the physical design of the holes - determines what can be plugged into it. As both "halves" are the same configuration, either one can provide 20 amps. You should note, however, that trying to pull 40 amps from one 20 amp circuit will absolutely trip the breaker.

Updated on March 15, 2018

Original Article:

An Electrician Explains How to Wire a Switched (Half-Hot) Outlet
By Dan Harmon