Overhead service drop cables are the cables that supply outdoor overhead power lines. They are a new power transmission method between overhead conductors and underground cables, which began research and development in the early 1960s.
Overhead service drop cables are composed of an insulation layer and a protective layer, similar to the production process of cross-linked cables. Although they are more susceptible to external interference and are not aesthetically pleasing, they are widely used in places where it is difficult to lay underground cables due to their high power supply reliability, stability, and convenient maintenance.
How we select overhead service drop cable ?
The three types of aluminum service drop cables are duplex service drop cable, triplex service drop cable, and quadruplex service drop cable. They differ according to the number of conductors and common applications. Let’s briefly focus on the role of each of these.
Duplex service drop cables with two conductors are used in single-phase power lines for 120-volt applications. They are frequently used in lighting systems outdoors, including street lighting. Moreover, they are often used in the construction business for temporary service. Fun fact- American duplex overhead cable sizes are named after dog breeds, including setter, shepherd, and chow.
Triplex service drop cables with three conductors are used to carry power from the utility lines to customers, in particular, to the weather head. Again, American triplex service drop cables have an interesting story to their name. They are named after the species of sea animals, such as snails, clams, and crabs. Cable names include Paludina, Valuta, and Minex.
Quadruplex service drop cables with four conductors are designed to supply three-phase power lines. They connect pole-mounted electrical transformers, mostly located in the rural areas, with the service heads of the end-user. Quadruplex cables that pass the requirements of NEC are named after horse breeds, such as Gelding and Appaloosa.
Construction of Aluminum Service Drop Cables
Despite varying purpose and number of conductors, all overhead electrical service wires have similar construction. The conductors of these cables are made of aluminum alloy 1350-H19,6201-T81 or ACSR.
They have a cross-linked polyethylene XLPE insulation that offers great protection from the risks of outdoors. in particular, it has excellent resistance to moisture, weather conditions, and the impact of various chemicals. The operational temperature of aluminum overhead cables with XLPE insulation is 90 degrees Celsius. Rarely, polyethylene insulation may be applied instead of the XLPE insulation. In this case, the operational temperature is reduced to 75degrees, which is something to have in mind when thinking about your electrical project. The voltage rating of all overhead electrical service wires is600 volts.
All aluminum service drop cables have a neutral conductor or a messenger wire. The goal of the messenger conductor is to create a neutral path for electricity to escape and avoid accidents, which is crucial in the environment of outdoor cabling. Messenger wires can be made of different materials, such as AAC, ACSR, or another type of aluminum alloy.
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Post time: Sep-20-2024