In simple terms, the single-core wire and multi-core wire of the electronic harness are actually the difference between single-strand and multi-strand. Multicore core wires are thinner than single-core hard wires, and the current has a skin effect. When the cross-sectional area of the single-strand wire is equal, the current transmission capacity is relatively larger, and the heat generation must be greater than the single-strand wire. The multi-strand wire is soft and easy to operate, and the hardness of the single core is not easy to operate. The single-core hard wire stripped insulation is a solid copper wire, the cross-sectional area is generally 1.5mm2, 2.5mm, 4mm2. Regarding why the material uses copper instead of aluminum, the reasons are: large internal resistance, low current consumption, low tensile strength, poor tensile strength, easy oxidation layer, and short service life.
Therefore, the electric devices use multi-core wires. Just like the wiring harness used for our cooling fans, they are multi-core wires. Like TVs, their power cords are also multi-core wires. Nowadays, household wires have begun to promote multi-core wires, but multi-core wires are really "safe" and "easy to use" as the promoters say? in fact is not necessarily so.
So, why can't multi-core flexible wires be directly like single-core hard wires, put the wire ends directly into the terminals of switches and sockets, and directly tighten them with screws? This is really a mystery, is it repeated in one fell swoop?
Simply put, the multi-core flexible wire is directly inserted into the terminal of the switch panel and fixed directly, and the following problems exist:
1. For wires with the same cross-sectional area, the multi-core flexible wire core wire has a smaller diameter than the single-core hard wire. Tighten it directly with screws, each core wire is not evenly stressed by the screw, which will cause some of the heavily stressed core wires to break. The tighter the fixing, the more severe the strand breaking phenomenon, and the actual total area of the wire at the joint is reduced, which is equivalent to reducing the wire diameter specification and the load carrying capacity of the wire. At the same time, this also cause failures such as short circuits and open circuits.
2. Since the number of core wires of multi-core wires that are really compacted and fixed by screws can only be a few, most of the core wires will spread out as the screws are tightened, poor contact with the switch socket, there is a large contact resistance, causing local fever, which may cause fire, and there are obvious hidden dangers.