A busbar is considered "hot" when it operates at high temperatures due to high current density ( I2Rcap I squared cap R
Joints are the "hot spots" of any busbar system. The Indal Handbook emphasizes:
Core Metallurgy and Electrical Properties of Aluminium Busbars indal handbook for aluminium busbar hot
Pre-job planning (mandatory)
The naturally occurring oxide layer must be removed, and a jointing compound applied to prevent re-oxidation. 4. Troubleshooting and Maintenance A busbar is considered "hot" when it operates
How the busbar reacts to electrical loads.
is a constant depending on surface treatment, orientation, and ambient temperature.) Troubleshooting and Maintenance How the busbar reacts to
Unlike copper, aluminium forms a tenacious oxide layer (Al²O³) in microseconds. When you torque a new busbar joint to the handbook's recommended 35 Nm (for an M12 bolt), the initial contact is only through microscopic peaks—the "asperities." When current flows, these tiny contact points become incandescently hot locally while the bulk bar remains cool.
Proper sizing is essential to prevent excessive thermal expansion and failure. Current Carrying Capacity ( Iccccap I sub c c c end-sub
Aluminium busbars are the backbone of modern low-voltage power distribution systems, offering a lightweight, cost-effective alternative to copper. When designing electrical panels and power distribution units, managing the thermal performance—or "hot" conditions—of these conductors is critical.
Instead of a single massive thick bar (e.g., 120x10mm), use multiple thinner bars (e.g., 120x5mm x 2) separated by a gap equal to their thickness. This reduces AC resistance and lowers the operating temperature by 15-20°C.