6 Minutes Make You Know Why Aluminum Wire Cause Fire Easily Than Copper Wire

Why does the aluminum electrical wire cause fire easily than copper electrical wire in electrical circuit? This article dedicated to help you figure out this problem you may meet with whoever you are a buyer or a wholesalers.

There are 2 aspects influencing the performance of electrical aluminum wire and copper electrical stranded wire in the electrical circuit, firstly we need focus on the elemental properties they have respectively, then we need taking into what will happen when they are connected in the circuit.

The properties differences

1. Load power: when the cross-sectional area of copper electrical stranded electrical wire and stranded electrical aluminum wire are same, copper electrical stranded wire load power is greater than stranded electrical aluminum wire.  

2. Flexibility: copper electrical stranded wire has better flexibility, convenient bending and strong fatigue resistance.  Stranded electrical aluminum wire is relatively easy to break when bent.  

3. Stability: stranded electrical aluminum wire is very easy to oxidize, so that the resistance becomes larger, reduce wire load, prone to safety problems.  However the copper electrical stranded conductor core is extremely stable.  

4. Resistivity: copper electrical stranded wire resistivity is small, compared with stranded electrical aluminum wire resistivity is lower than 1.68 times, resulting in stranded electrical aluminum wire power loss ratio. Larger, more serious fever, affecting the utilization rate of electricity.  

5. Price: aluminum wire price is much cheaper than copper wire, copper wire price is generally many times aluminum wire, copper wire than  aluminium wire.  

4 different points when in the circuit

As we know, the danger of stranded aluminum electrical wire fire is much greater than copper electrical stranded wire, the fire of aluminum wire is not in the aluminum wire itself but in the connection of aluminum wire. Compared to the copper electrical stranded wire, aluminum wire connection is more dangerous for the following reasons:  

• The surface of stranded aluminum electrical wire is easy to oxidize in air  

There is more or less membrane resistance on the surface of all conductors.  If the film resistance causes the connection to overheat, and the overheat increases the film resistance, The more conductive the situation deteriorates, and this kind of overheating is particularly serious in stranded aluminum electrical wire connections.  This is because the surface of the aluminum wire is scraped smooth clean, it only needs to be exposed to air for a few seconds to be oxidized and immediately form a layer of alumina film.  Its thickness is only a few micro, but it has a high resistivity, resulting in a large film resistance.  Therefore, in the construction of aluminum wire connection, should be in the scraping dry. After cleaning the surface of the aluminum wire, apply conductive paste immediately to cut off the contact between the surface of the aluminum wire and the air, otherwise the contact resistance will increase.  

• High expansion coefficient  

Aluminum has an expansion coefficient of 23×10-6/℃, 39% larger than copper and 97% larger than iron.  When the stranded aluminum electrical wire is connected to these two metal conductors  

When the current is connected and passed, the connection point is heated by the presence of contact resistance.  All three conductors expand, but aluminum expands more than copper or iron .So that the aluminum wire is squeezed.  After the line is cooled by power failure, the stranded aluminum electrical wire is slightly compressed and cannot be completely restored to its original state, so it is connected there is a gap and loose, and the formation of alumina film because of entering the air, so that the contact resistance increases. The next time electricity is turned on, the heat will be more intense, making the situation worse. In serious cases, it may be caused by abnormal heat or spark generation ignite a fire. For this reason, the aluminum conductor with large cross-sectional area should be equipped with transition joints when connecting copper and iron conductors.  Small cross-sectional area (not greater than 6mm2) The connection of stranded aluminum electrical wire should be made of spring crimping cap, so that no matter whether the connection is energized, there is no heat, connection contact the surfaces are under the pressure of the spring to allow air and moisture to enter without a gap, thus keeping the connection conductive.  

• Easy to appear electrolytic corrosion  

If there are acidic or alkaline liquids between the two metals at different potentials, the two metals will form local batteries. The potential of aluminum is -0.78V, and copper is -0.17V, when there is salty water between aluminum conductor and copper conductor, this kind of local battery is formed. The low potential aluminum conductor will be corroded by ionization and the contact resistance will increase.  

• Easy to be corroded by hydrogen chloride  

Another problem may occur with PVC insulated aluminum - cored wires and cables. To prevent the PVC insulation from decomposing into chlorine hydrogen gas, PVC insulation added to prevent decomposition of hydrogen chloride stabilizer.  But when the line temperature exceeds 75℃, for example, when the connection temperature is too high due to circuit overload or other reasons, the stabilizer can no longer prevent the formation of hydrogen chloride, and hydrogen chloride corrodes aluminum, which also increases contact resistance and fire risk.  

Now have you got the differences between stranded aluminum electrical wire and copper stranded electrical wire? Any more question about them, you can consult us and we will try our best to answer you or you have any need on them, you can contact us anytime.

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