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| Figure 8-1 Magnetic fields: (A) Intensity of magnetic field around conductor depends on current flowing in conductor; (B) currents flowing in same direction tend to force conductors together; (C) currents flowing in opposite directions tend to force conductors apart. |

| tors lie adjacent to one another, a force of attraction (Fig. 8-1B) or repulsion (Fig. 8-1C) will exist between them because of the interaction of their magnetic fields. If the currents are extraordinarily high, the forces produced may be enormous. |

| The magnitude of the current flowing in a circuit under normal conditions depends upon the load and the apparatus or appliances connected to the circuit; it is referred to as the normal, or load current. |

| When, however, current flow is not restricted by the load connected to the circuit, because of the failure of one of the circuit components (including the conductors themselves), there is nothing to limit current flow except the resistance of the circuit conductors from the source to the point of failure and the resistance of the fault itself (Fig. 8-2). The current is thus apt to be extremely large and its effects very destructive, making it imperative to interrupt the circuit as quickly as possible to hold damage to a minimum. |

| Consider a dead short circuit, that is, one with no resistance to limit the current flow, applied on conductors that are close to a generator or other source of electric power. Assume also that the voltage generated is 5000 V and |

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