[Aluminum Wire Fire Crisis in Old Houses] Aluminum Wire is used in a 40-year-old house in Shuangbei? Oxidation, overheating, oxidation and fire of aluminum-copper joints and the method of replacing copper wires in the whole room

Electrical bomb hidden in the wall of a 40-year-old house in Taipei

When purchasing 40 to 50-year-old apartments or medieval buildings in the greater Taipei area for renovation and decoration, many homeowners will be horrified to discover when they dismantle the old distribution boxes or switches and sockets: The wires pulled out from the depths of the wall, the internal metal conductors are not the familiar red copper color, but silver-white "Aluminum Wire"! Even at many screw joints where aluminum wires and copper wires meet, black carbonized burn marks and melted plastic insulation have appeared. In the field of hydropower engineering in Taiwan, old aluminum wires are recognized as one of the most dangerous invisible killers causing residential wire fires. For homeowners and real estate commercial investors, the inventory and disposal of old aluminum wires is an extremely high priority mechanical and electrical safety task.

Fact check: Why was aluminum wire used back then? Three fatal flaws of aluminum wire

In the 1960s and 1970s of the Republic of China (1970s to early 1980s), due to the soaring global international copper prices, some Taiwanese builders used cheaper "aluminum core wires" to replace traditional copper wires when building homes in order to reduce construction costs. However, after decades of use, aluminum wire has revealed three fatal physical and chemical defects:

• High Thermal Expansion Creep: The metal thermal expansion coefficient of aluminum is more than 30% higher than that of copper. When high-power electrical appliances (such as microwave ovens and hair dryers) are turned on at home, the aluminum wire will rapidly heat and expand; it will cool and shrink after the electrical appliance is turned off. After thousands of "heating expansion-cooling contraction" cycles, the aluminum wire locked on the switch socket screw will gradually loosen and deform, forming a tiny gap and triggering a violent "micro-arc discharge (Arcing)", generating a high temperature of thousands of degrees and causing a fire!
• Extremely rapid surface oxidation produces high resistance (Aluminum Oxide): When aluminum is exposed to air, it will quickly oxidize to form "aluminum oxide (Al₂O₃)". The copper oxide produced by the oxidation of copper still has some conductivity, butaluminum oxide is an extremely high insulator! High resistance will cause extremely high abnormal heat to be generated when current passes through the connector, directly melting the surrounding plastic pipelines.
• Galvanic Corrosion of Dissimilar Metals: If aluminum wires and copper wires are directly twisted together, in the humid air of Shuangbei, the two metals with different potentials will undergo galvanic corrosion, causing the metal to quickly rust, powder and break.

Real Estate Acquisition Due Diligence Home Inspection: How to identify aluminum wire?

When commercial real estate investors acquire old properties in Shuangbei, they should conduct the following house inspections:

1. Open the main distribution box and observe the wire core: Check the NFB circuit breaker terminals. If the wire is silvery white and has a thick wire diameter (usually 3.5mm² or 5.5mm² aluminum wire), it proves that the whole house wiring contains aluminum wire.
2. Inspect the inside of the outlet wall box:Disassemble the shell of the socket in the living room or bedroom, observe whether there are traces of mixed aluminum and copper wires, and check whether the plastic wall box is deformed and yellowed by overheating.

Comprehensive construction method: whole room replacement of primary copper wires vs. copper-aluminum transition joints

To dispose of old aluminum wires, water and electricity experts provide the following two levels of repair project disposal:

Conclusion: Eliminate dangerous aluminum wires and build a solid security line for real estate

Residential wire fires often occur in milliseconds, and old aluminum wires in the walls of a 40-year-old house are the most unstable electrical hazards. When renovating old houses or acquiring assets of historic houses in Shuangbei, you must not take any chances with old aluminum wires. Only by insisting on replacing the entire room with first-class pure copper wires that comply with national standards and equipping with qualified NFB circuit breakers can the threats of power outages and fires be completely eliminated, and the most solid guarantee for the safety of life and property of the whole family can be provided.

The Ministry of Economic Affairs' latest "Regulations on Consumer Electrical Equipment Installation" and the key points of electricity safety in old houses

Due to the popularity of high-power household appliances (such as air fryers, microwave ovens, dishwashers, instantaneous electric water heaters, and IH furnaces) in recent years, the Energy Administration of the Ministry of Economic Affairs has revised the "Regulations on Consumer Electrical Equipment Installation" many times to strictly require the diversion and protection mechanisms of residential electricity circuits. Statistics show that more than 30% of building fires in Taiwan are caused by electrical factors, among which "old wire insulation deteriorates and short circuits", "socket contacts are oxidized and loose, poor contact" and "non-fuse switch (NFB) overloaded and failed to trip" are the three main fatal causes.

Old apartments in Shuangbei that are more than 30 years old have a total original designed power capacity of only 30A to 40A, and several rooms often share the same 1.6mm or 2.0mm circuit. In the modern standard safety configuration, kitchen electrical cabinets, bathroom equipment, and air-conditioning and heating machines must all be equipped with 5.5mm² dedicated circuits (single circuit and single socket). It is recommended that the main switch box be upgraded to a busbar (Busbar) integrated distribution board, and the total amperage is increased to 75A or 100A (a qualified electrical appliance contractor needs to be entrusted to Taipower to review the additional power capacity).

Residential electricity self-test and regular inspection checklist

• Appearance and temperature of the socket: Touch the outer cover of the commonly used socket lightly with the back of your hand. If it feels lukewarm or if you find that the plastic socket is yellowed and charred, or the plug is loose and shaking after being plugged in, it means that the internal copper plate clamping force is exhausted or the contact resistance is too high, and you should immediately cut off the power and replace it.
• Regular testing of leakage circuit breakers (ELCB): For leakage circuit breakers in humid places such as balconies, bathrooms, and kitchen sinks, regulations require that the "TEST button" on the switch be pressed once every 1 to 3 months to confirm that it can automatically trip and cut off the power supply instantly.
• Serial connection and overloading of extension cords are strictly prohibited: Extension cords should be purchased with 2.0mm thick wire diameter products that have CNS certification and automatic overload power-off protection. Do not share the same extension cord with high energy-consuming appliances to ensure zero hidden danger to life and property at home.