The safe maximum wattage capacity of a 20-amp breaker in a 120-volt residential electrical system is typically 1,920 watts. This is based on the 80% rule, which states that a circuit should not be loaded to more than 80% of its maximum capacity for continuous use. Applying the 80% rule to a 20-amp breaker (20 amps × 120 volts = 2,400 watts) results in a safe maximum watt capacity of 1,920 watts (2,400 watts × 0.8 = 1,920 watts). Following this guideline helps prevent circuit overload, ensuring the safe and efficient operation of your electrical system. If you need expert guidance on circuit breakers and electrical installations, the Electricians Service Team is available to help.