Bimetallic Terminal Blocks: Behind Electrical Connection Safety, Have You Really Chosen The Right One?

Many engineers overlook a crucial detail when wiring: copper and aluminum cannot be directly joined. Copper has a high electrode potential, while aluminum has a low one. In humid environments or those containing electrolytes, a galvanic cell reaction occurs, causing the aluminum end to gradually oxidize and corrode. Over time, the contact resistance steadily increases, leading to abnormal heating at the connection point. This can result in a short circuit, or even equipment burnout or fire. This is why bimetal cable lug is so important—it fundamentally severs this chain of corruption.

Friction welding technology truly unites copper and aluminum.

The core of bimetal terminal lug is not simple mechanical splicing, but rather the formation of a metallurgical-grade bonding layer at the copper-aluminum interface through friction welding. This transition layer blocks the electrolyte penetration path, eliminating any gaps between the copper and aluminum that can be corroded.

Specifically, the changes brought about by this process are reflected in the following aspects:

• Electrochemical corrosion: The copper-aluminum alloy transition zone blocks the formation conditions of the galvanic cell reaction.

• Contact resistance: The molecular-level bonding at the welding interface maintains the resistance value at an extremely low level, reducing the risk of heat generation.

• Mechanical creep: Compared with ordinary mechanical connections, friction welding points can maintain stable contact pressure even after multiple thermal cycles.

• Sealing protection: For humid or corrosive environments, the terminal welding area needs to be sealed with heat shrink tubing or sealant.

Electrical connection safety starts with selection.

Many people mistakenly believe that as long as they use type bimetallic lugs price, the connection is all set. In fact, improper selection can also lead to hidden dangers.

The matching degree between the conductor cross-sectional area and the terminal inner diameter directly affects the contact area after crimping; the rated current of the terminal should have a 20% to 30% margin, not just enough; the temperature range of the working environment, whether vibration or corrosive gases are involved, should all be taken into account when selecting a model. Products conforming to GB/T 9327-2008 national standard or IEC 61238-1 standard certification have undergone 1000 AC thermal cycle tests. This is the true hard indicator for judging the safety of electrical connections, not just the manufacturer's product description.

Installation details determine long-term stability.

Even if the product itself is up to standard, errors in the installation process can ruin everything. During crimping, the wire must be fully inserted into the metal sleeve of the terminal, not just the insulation layer. After crimping, check for any exposed or protruding aluminum wires; these details will form new oxide points after operation. For aluminum alloy cables, the oxide film on the conductor surface must be removed before hydraulic crimping to form a true metal-to-metal bond.

Bimetallic terminal blocks solve the most difficult compatibility problem in copper-aluminum coexisting systems, but safe electrical connections ultimately rely on the combined effects of correct selection, standardized installation, and regular inspection.