If this metal becomes energized (a ground fault), current travels on the bonded metal and quickly increases to an amount that trips the circuit breaker or blows the fuse. Most current in the bonding and ground system flows back to the transformer some may trickle out through the copper that leads to the grounding node.īonding connects the non-current-carrying metal parts of the electrical system, such as metal boxes and metal conduit, in a continuous low-resistance path back to the main service panel. The grounding wire and bonded metal conduit pick it up and channel it back to the main service panel, where the overcurrent device is tripped, stopping further flow of current. RIGHT: Current is detoured by a loose wire in contact with the metal box. LEFT: Normal current flow – Current enters the electrical box along a black hot wire and then returns to the service panel along a white neutral wire. In the present chapter, we shall study some of the basic laws concerning steady electric currents. You should understand the difference to safely work on electrical circuits. Each week-long course covers the basics of industry technology, industry structure and regulation, revenue require-ments, cost allocation, rate design and rate-case procedures. Current is measured in amperes, which is often shortened to amps. This flow of electrons is referred to as current and is designated by the symbol I. You will see the terms grounding and bonding used in this and other books about electricity. Electricity is the flow of electrons in a conductor from one atom to the next atom in the same general direction. From the service panel, current returns along the uninsulated neutral service wire to a power pole transformer. In a household wiring system, this return path is provided by white neutral wires that return current to the main service panel. Contrary to popular belief, electricity will take all available return paths to its source, not just the path of lowest resistance. Current then leaves the house on a large neutral service wire that returns it to the utility transformer.Įlectricity always seeks t o return to its source and complete a continuous circuit. Current returns to the service panel along a neutral circuit wire. A fuse or a circuit breaker protects each circuit in case of overloads. If a circuit carries too much current, it can overload. The service panel also has a bonding wire connected to a metal water pipe and a grounding wire connected to a metal grounding rod, buried underground, or to another type of grounding electrode. The grounding wire conducts current in the event of a ground fault and helps reduce the chance of severe electrical shock. For safety, all modern circuits include a bare copper or green insulated grounding wire. Hot wires are black or red, and neutral wires are white or light gray.

Pdf basics of electricity