![]() If it does, your ground (or other wiring) is faulty and ought to be repaired! Setting it up: Touching the neutral line and ground should not light the bulb. Likewise, touching the hot line and ground results in a ZAP (you need to make sure that the clip touching "ground" is pushed through the sand and actually touches the aluminum plate, which is electrically wired to true ground). But, touching one clip to the neutral line and the other to the hot line lights the bulb-ZAP. Touching both of the clip ends to the hot or live line does not light the bird bulb. The "bird lightbulb" has two insulated wires attached (with alligator-clip ends)-they represent the bird's feet. Otherwise, the bulb does not light, which indicates a safe condition.Ī separate neon bulb is wired across the two transmission lines to indicate to the audience that indeed there is a voltage present, and also serves as a reminder to the demonstrator that the power is on and caution is in order. Since we don't want to zap birds, a light bulb becomes a surrogate for the bird-if there is a voltage (difference) across the light bulb, it lights (which is equivalent to ZAP). Nevertheless, the "transmission lines" are bare (uninsulated) copper wires with no current-limiting resistors or fuses in line, so use caution in this demonstration. Rather than a 20,000 volt transmission line, the demonstration operates at 120 volts from any outlet. However, if a power line is down (on or near the ground) and a bird (or person) touches it-ZAP! In this situation there is a voltage difference across the bird or person, namely the difference between the wire voltage and ground. If the bird could straddle a neighboring wire at a different voltage-ZAP! But this doesn't happen because power lines are strung sufficiently far apart. Since there is no voltage difference across its body, there will be no current flowing through its body, and thus the bird does not get electrocuted. Although the bird on the wire would also be at this voltage, there is no part of its body that isn't. The voltage on the wire is the voltage of the whole length of wire with respect to the ground. In this situation the conducting medium is a bird sitting on a high-voltage wire. ![]() The important concept conveyed is that there needs to be a voltage difference across a conducting medium for current to flow through the medium. ![]() Circuit length refers to the sum of the route length of each circuit on a line.Ģ.Due to the Accounting Rules for Electricity Business amendment (effective from March 29, 2000), distribution facilities with voltage over 20 kV have been included in transmission facilities since FY1999.ģ.The sum is not equal to a total of breaskdown due to rounding.Why doesn't a bird sitting on a high-voltage wire get electrocuted? This demonstration addresses that question and serves as a model of the situation. The combined circuit lengths of overhead and underground transmission lines total approximately 40,000 km, which is equivalent to the circumference of the earth.ġ.Route length refers to the total length between two points on a line (horizontal length between supports). Overhead transmission lines consist of a route length of 14,781 km and circuit length of 28,365 km, with 50,369 supports, while underground transmission lines consist of a route length of 6,391 km and circuit length of 12,325 km. The table shown below indicates the amount of equipment in use at the end of FY2016. Circuit Lengths of Overhead and Underground Transmission Lines ![]()
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