Electrical Question.?

Question

Calculate the maximum total resistance below which a 120 volt circuit will trip a 15 amp breaker

Answer 1

Total maximum resistance would be infinity. Higher resistance, lower current!

Minimum resistance would be e/i=r

Answer 2

maximum total resistance = 120/15 = 8

the answer is 8 ohm

Answer 3

When the amperage reaches 15 Amps, the breaker is supposed to trip, most likely to insure the conductor connected to the breaker will stay within its "ampacity" of 15 amps.  When the impedance across the 120 decreases to the point that 15 * Z = 120, the breaker must trip.  So Z=120/15=8 ohms.  This would be an 1800 VA load.  Where VA is Volt Amperes since the load could be composed real power (watts) AND reactive power (Vars).  Watts are the product of the volts times the component of current IN PHASE with the voltage and vars are the product of the volts times the component of current 90 degrees OUT OF PHASE with the voltage.