Differences between copper and aluminum connections.
Aluminum wiring has the following advantages:
- This feature is important when installing power lines, the length of which can reach tens or even hundreds of kilometers.
- Accessibility. When choosing a material for wiring, many are guided by the cost of the metal. Aluminum is inferior, respectively, which explains the lower price of products from this metal.
- Resistance to oxidative processes (relevant in the absence of contact with open air).
- Presence of a protective film. During operation, a thin coating forms on the aluminum wiring, which protects the metal from oxidative processes.
Aluminum also has a number of disadvantages that you should be aware of:
- High resistivity of the metal and tendency to heat. For this reason, the use of a thread smaller than 16 sq m is not permitted (taking into account the requirements of the PUE, 7th edition).
- Loosening of contact joints due to frequent heating during heavy loads and subsequent cooling.
- The film, which appears on the aluminum wire in contact with air, has poor current conductivity, which creates additional problems for the joints of cable products
- Fragility. Aluminum threads break easily, which is especially important with frequent overheating of the metal. In practice, the service life of aluminum wiring is no more than 30 years, after which it needs to be changed.
Now let’s find out in more detail which wire is better between copper and aluminum. In this regard, there are many stereotypes and misconceptions:
- Durability. The service life of copper wire is believed to be longer than that of aluminum. This is a misunderstanding. Inquiring with special reference books, it is possible to make sure that the resource of wires of both types of metal is identical. For products with single insulation it is 15 years and with double insulation 30 years.
- Tendency to oxidize. When using aluminum cable, it is worth remembering its tendency to oxidative processes. At school, we were told that Al (aluminum) is a metal that actively interacts with oxygen, which is why a thin film appears on its surface. The latter protects the metal from further decay, but impairs its conductivity. By isolating the wire from the environment, the risk of oxidative processes is minimized. The best option is to use special terminal blocks with conductive paste. The peculiarity of the latter is to improve the quality of the contact connection between the two wires and to remove the oxide film from the metal. Furthermore, a special lubricant prevents the aluminum from coming into contact with the ambient air.
- Power. Copper wiring is considered more durable and able to withstand more bends. GOST states that a copper wire must withstand 80 bends and made of aluminum 12. If the wiring runs in a wall, floor or is hidden under the ceiling, this function is not so important.
- Cost. The price of an aluminum wire is 3-4 times lower. But when choosing, it is important to remember that a copper wire with a cross section of 2.5 sq m is designed for a current of 27 amperes. If aluminum wiring is chosen, the wire must be 4 square meters thick (rated current 28 Amps).
- Resistence. When deciding what to choose, aluminum or copper wires, it is worth considering the different resistivity. For copper, this parameter is approximately 018Ohm*sq.mm/m, and for aluminum 0.028. But it is worth considering that the total resistance (R) of the conductor depends not only on the mentioned parameter, but also on the length and area of \u200b\u200bthe conductor. Taking into account the fact that aluminum wires of a larger cross section are used for the same load, the total R of copper and aluminum products will be approximately identical. The maximum resistance occurs at the joints: following the suggestions discussed above, there are no problems in this sense.
- Ease of installation. Connecting aluminum wires is believed to be a more difficult task. This is only relevant for the normal combination of cables, by twisting. In the case of using end fittings, terminal blocks or bolts, this problem disappears.