Aluminium
- Cheaper alternative to copper
- Used from 1950s to 1970s, and old stock sometimes
used into the 1980s.
- The insulation & sheathing is mostly the same as T&E – PVC for decades, may be rubber on older cable.
- A known fire risk
- Aluminium cable creeps, oxidises & fractures, all of which can cause fires.
- Requires special connections, do not connect to old aluminium cable using connectors intended for copper.
- Al requires a larger conductor size than Cu for the same current rating
- Presence of aluminium cable may be considered a material fact for insurance.
- The main problem with aluminium cable is its thermal expansion coefficient. Repeated temperature cycling causes it to come loose at connection points, and it then oxidises, and aluminium oxide is an insulator. Bad connections generate excessive heat and fire can break out.
- Having said all that aliminium cable still has its uses and so is still being manufactured today. Aluminum provides a much better conductivity to weight ratio than copper, and therefore is used in power wiring of some aircraft. With the prices of copper going through the roof people are looking at aluminium again and trying to work out better ways of using it such as for car speaker systems.
