Insulated Aerial Bunched Cables

Aerial bundled cables (also aerial bundled conductors or simply ABC) are overhead power lines using several insulated phase conductors bundled tightly together, usually with a bare neutral conductor. This contrasts with the traditional practice of using uninsulated conductors separated by air gaps. This variation of overhead power lines utilizes the same principles as bundled conductors, except that they are closer together to the point of touching but each conductor is surrounded by an insulating layer (except for the neutral line).

The main objections to the traditional design are that the multiple conductors are considered unappealing, and external forces (such as high winds) can cause them to touch and short circuit. The resultant sparks have been a cause of bushfires in drier climates. In the UK where some supplies to rural property are converted to PME/MEN from TT Earthing system concerns have been expressed that the lower conductor alone may be broken, (by high vehicle or falling tree for example) but with the upper phase conductors intact. This is a potentially dangerous fault condition. With ABC, a simultaneous disconnection of all conductors is more likely.

In moister climates, tree growth is a significant problem for overhead power lines. Aerial bundled cables will not arc over if touched by tree branches. Although persistent rubbing is still a problem, tree-trimming costs can be reduced.

Areas with large trees and branches falling on lines are a problem for aerial bundled cables as the line degrades over time. Due to the very large strain forces cracking and breaking insulation can lead to short circuit failures which can then lead to ground fires due to dripping of molten insulation.

Low voltage ABC has already been developed in several countries across the globe and promises to be cheaper, safer, more reliable, require less tree clearing and pruning, be more aesthetic, be less labor intensive, require less maintenance and eliminate bushfires being initiated by conductor clashing.