Busbar VS Cables for Riser Applications

We already know the using busbar in the power distribution system has many advantages. It is well arranged, safe and reliable. I already posted an article about the Why Busbar Trunking System is Preferred Over Cabling? In this post, we will discuss the Busbar VS Cables for Riser Applications.

Busbar VS Cables - For Riser Application
Busbar VS Cables – For Riser Application

We will discuss some issue and it will explain the position of using busbar and cable for riser application

  1. Main Switchboard

Busbar: Need only 1 outgoing for each riser. Lower cost and size for the main panel.

Cable: Need 1 outgoing for each circuit. Hence, 20nos MCCB outgoing. Higher cost and larger space requirement in the electrical room.

  1. Shaft Size

Busbar: Typical size of 1600A riser is 185mm x 180 mm. Leads to big savings on riser shift size, and hence more usable floor area on every floor.

Cable: Using 4 core cables, and considering 1 cable per feeder, you need 20 cables on the lowest floor. Large space required for cables/ cable tray.

  1. Number of Circuits

Busbar: Just one circuit can cover all floors.

Cable: On Circuit per floor. Hence for a 20-floor building, you need 20 circuits.

  1. Fire & Safety

Busbar: The volume of insulating materials used in trunking is reduced to a minimum so combustive energy is considerably lower than cables. The insulating materials used do not release corrosive or toxic gases in the event of a fire. Once the source of the fire is removed, these materials are extinguished in a few seconds so that the effect of the fire is minimized.

Cable: The high concentration of insulating materials used in cables and conductors involves a very high level of combustive energy.

  1. Future Expansion

Busbar: By providing extra tap off slots on each floor at the design stage, the owner only has to procure a tap off box and plus it in wherever additional load is required. As the plugin can be done live, there is no shut down required for any of the existing clients/ circuits.

Cable: If the load on any floor exceeds the initial plan, an owner has to run an additional cable from a spare feeder on the mainboard to that floor.

  1. Combustive Energy

Busbar: 1600A – approx 5 k Wh/sq,m. Combustive energy is typically 80% to 90% less than cables.

Cable: 1600A – approx 60 k Wh/sq.m.

  1. Fault Withstand Levels

Busbar: Much higher – typically a 1600A riser has a fault withstand capability of 60 to 70 KA. Safer in an electrical fault.

Cable: Limited by conductor size each circuit.

  1. Voltage Drop

Busbar: Much lower impedance. Hence substantially lower voltage drop.

Cable: High impedance if you choose cable size based on each floor current rating.

  1. Installation Time

Busbar: Each riser on a 20-floor building can be installed in approximately 2 to 3 days.

Cable: Much longer.

Related: Various Types of Electrical Cable Conductor

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