An overloaded electrical outlet sparked a five-alarm blaze that tore through a Hamilton Heights apartment yesterday, drawing 300 firefighters to the scene and leaving 19 of them injured, authorities said.

The fire broke out in a seven-story brick building on West 139th Street between Broadway and Amsterdam Avenue at around 3:45 p.m., the FDNY said.

“It started in the master bedroom on the sixth floor,’’ said building super Abel Santos. “There’s only one outlet. They had the air-conditioning and all appliances plugged in, and it overheated.’’

Nineteen firefighters were treated for smoke inhalation — 11 at the scene and eight at Weill Cornell Medical Center.

A civilian was treated for minor injuries.