Summary of key risk factors observed on usage of Aluminium cables at various commercial buildings – Thermography Study

1. Aluminium Conductor breakage during testing/active pull test.
2. Insulation damage over a period of time – brittleness, cracking and subsequently clearance decreases and hence chance of overheating and short circuit.
3. Absence of bimetallic lugs causing overheating and oxidation
4. Due to sharp bending radius stress on the terminations and subsequent overheating or chances of insulation damage
5. Addition of future load capacity becomes limited due to lesser conductivity and ageing
6. Loading capacity on support structure and cable trays increases due to equivalent Aluminium conductor usage.
7. Due to increased lug size of Al conductors, the termination clearances get affected on MCCB/ACB/MCB/Isolator/SFU terminals (E.g. absence of lugs and difficulty of termination of multi-strand conductors on fuse box terminations)
8. Installation of multiple cable runs causes uneven heating as well as load unbalance.
9. Non-Usage of bimetallic lugs with MCCB terminals (of Copper) causes even higher rated aluminium conductors to experience hotspots
10. Due to compulsion of using multi-run cables because of Aluminium’s Lower current carrying capacity of Al conductor and further uneven current distribution in these runs most likely due to unequal contact resistances and impedances, localised hotspots are created which are hard to resolve. Further this is a major O&M Issue due to unavailability of space to rectify/replace cables/lug/tightening etc.
11. Expansion and contraction cycles in Aluminium have greater impact compared to use of copper (due to lower coefficient of thermal expansion of Copper). Overtime these cycles can loosen connections. If normal inspections of these connections are not performed and loose connections are not tightened there is an increased risk of fire from arcing