Overcurrent Protection-NEC Article 240 and Beyond

This is a single license Digital eBook PDF File that is downloadable, and password protected     eBook Description An overcurrent is caused by a short-circuit, ground-fault, or an overload. A short-circuit may be hundreds or even thousands of times above the normal operating current. This type of fault may be an arcing fault between ungrounded conductors or between an ungrounded conductor and a grounded (usually, a neutral) conductor, a line-to-line arcing fault may produce a current of 74% of a 3-phase bolted fault. A line-to-neutral arcing fault will be somewhat less. A line-to-line bolted fault, the equivalent, of the conductors bolted together, may be up to 100% of the available short-circuit current. A line-to-neutral bolted fault may be in excess of 100% of the 3-phase bolted fault at the source, but considerably less downstream. A ground-fault, that is, the equivalent of a connection between an ungrounded conductor and the equipment grounding system, will produce a current