LT Bus Duct Erection vs. Heavy Armoured Cables: Choosing the Right Power Distribution Medium

1. Current Carrying Capacity and Voltage Drop Comparison

For very high current requirements above 1000A, bus duct outperforms multi-core armoured cables in both current density and voltage drop performance. A 1600A rated aluminium bus duct occupies a single 200mm by 400mm duct cross-section, whereas achieving equivalent current rating using armoured cables requires multiple parallel sets of 300mm squared cables on cable trays, consuming far more real estate. Bus duct's lower impedance per unit length also results in significantly lower voltage drop over long distribution runs, which is critical for facilities where transformer secondary voltage must be maintained close to nominal at remote distribution boards.

2. Installation Complexity and Project Timeline

Armoured cables offer simpler installation where cable drum reels are pulled and terminated at both ends. Bus duct installation requires precision structural support brackets, careful weatherproof coupling of duct sections, and accurate alignment of joint assemblies. However, for long-run high-current feeders, the labour time difference largely disappears, and bus duct eliminates the need for multiple parallel cable routes and complex tray segregation planning. In high-rise buildings with vertical bus risers, bus duct is almost always faster than managing dozens of parallel armoured cable runs up stairwells and shaft openings with scaffold support at every floor.

3. Flexibility for Future Load Modifications

Armoured cable feeders are essentially fixed infrastructure. Modifying the routing, adding tapping points, or increasing current rating requires physically replacing or supplementing cables from end to end. Bus duct systems with plug-in tap-off boxes allow new loads to be connected at any point along the duct run without interrupting power to other loads. This inherent modularity makes bus duct the preferred choice for IT buildings and manufacturing plants where tenant reconfiguration, process expansion, or machine relocation is anticipated within the facility's operational lifespan, making every future modification dramatically simpler and less disruptive.

4. Protection Against Mechanical and Environmental Damage

XLPE steel wire armoured cables provide excellent mechanical protection for outdoor routes, underground burial, and environments with high physical hazard risks. Bus duct, though available in IP54 and IP65 rated enclosures, is generally preferred for indoor application in clean industrial environments, building service floors, and riser shafts. In areas with high ambient moisture, corrosive chemical vapours, or outdoor exposure, properly jointed SWA armoured cables with suitable weatherproof glands consistently outperform bus duct in maintenance-free operational life, requiring less ongoing inspection of joints and seals.

5. Life Cycle Cost Analysis Over 25 Years

Initial capital cost for bus duct is typically 30 to 45 percent higher than an equivalent armoured cable solution for the same current rating. However, over a 25-year facility lifespan, bus duct savings accrue through lower transmission losses, zero cable insulation ageing, elimination of joint maintenance costs, and far lower modification costs when loads are reconfigured. For projects with current requirements above 1600A and expected operational lives of 20 or more years, the life cycle cost advantage of bus duct is typically decisive when the full economic analysis including future modification costs is performed honestly.