Mike I understand that a breaker should trip under 3 different circumstances. 1 Overcurrent 2 Short circuit 3 Ground fault. Analyzing the code at 240 seccion I realized that if a ground fault occurs the breaker should trip because the metal enclosure of the main panel has a very low resistance that will cause a huge amount of current to flow through the EGC back to the source. Now lets change the scenario, suppose that a hot wire makes contact with the metal part of an appliance within the electrical installation and the protective overcurrent device is a 40 amps breaker ( MCB) and the resistance of that specific metal part is 10 ohms. Ohms law says I = V/R 120 V / 10 Ω = 12 amps. the question is, Will that breaker trip or not? I think it should not trip, then how do we clear that fault? Does the fact the ECG is connected to the neutral wire result in a short circuit in the event a hot wire touched the metal enclosure of an (equipment) appliance?