Uh no this is completely wrong. Not unless the breakers are really old and need replaced. Breakers typically won't trip until about 15-20% ABOVE their rating. So a 15A breaker wouldn't trip until you start pulling over 2Kw continuous/2.5kW instantaneous. Most modern houses are using 20A breakers and 12ga Romex now anyway so there's very very little chance of someone tripping a breaker at 80% of a 15A rating.