Indal engineers recommend that for a peak short-circuit current of 80kA, support insulators must be spaced:
The most referenced section of the Indal Handbook deals with . Aluminium forms a hard, high-resistance oxide (Al2O3) within picoseconds of exposure to air. The handbook provides a strict protocol to defeat this: Indal Handbook For Aluminium Busbar
Where "k" for E91E grade is listed as (for insulated conductors) and 152 (for bare, uninsulated bars in air). Indal engineers recommend that for a peak short-circuit
For rectangular bars at 50/60 Hz: | Bar thickness (mm) | Skin effect ratio (Rac/Rdc) | |--------------------|-----------------------------| | 3 mm | 1.01 | | 6 mm | 1.07 | | 10 mm | 1.20 | | 12 mm | 1.30 | | 15 mm | 1.45 | For rectangular bars at 50/60 Hz: | Bar
| Property | Rectangular | Tubular | |----------|-------------|---------| | Ampacity (same XS area) | Baseline | +10–15% (better cooling) | | Skin effect | High over 10 mm | Very low (current on OD) | | Bending/installation | Simple | Requires end connectors | | Cost | Low | Moderate |