Indal Handbook For Aluminium Busbar Hot Online

Unlike copper, aluminium has a higher coefficient of thermal expansion (23.8 x 10⁻⁶ /°C vs. copper’s 16.8 x 10⁻⁶ /°C) and different creep characteristics. When a busbar gets "hot" (operating at 85°C to 105°C), three things happen:

The INDAL handbook historically addressed these issues not as failures, but as design parameters. A "hot" busbar is acceptable provided the system is designed for it. indal handbook for aluminium busbar hot

For a 100mm x 10mm busbar, AC current crowds to the surface. Unlike copper, aluminium has a higher coefficient of

This is the most critical section of the INDAL Handbook. Most "hot busbar" failures occur at joints. The INDAL handbook historically addressed these issues not

| Issue | INDAL Solution | | :--- | :--- | | Creep (Al flows under pressure at 90°C) | Use Belleville washers (spring washers) that maintain constant pressure. Standard flat washers lose 50% clamping force after 3 thermal cycles. | | Oxidation | Apply zinc-filled or copper-filled inhibitor paste (e.g., Penetrox, Alnox). Do not use plain grease—it evaporates at 80°C. | | Dissimilar metals (Cu-Al) | Use bimetal plated washers or tinned Al lugs. Direct contact causes galvanic heating (additional 15-20°C rise). | | Torque | INDAL specifies 20-25 Nm for M10 bolts on 10mm thick bar. Over-torque strips threads; under-torque creates hot joints. |

The Indal handbook provides tables for Current Rating. If your busbar is operating in a "hot" environment (ambient temperature > 40°C), you must derate the current: