Home / Products / Busbar Trunking (BBT)
One system in place of cables and floor boards
Busbar trunking carries current from one point to another and taps off power to switchgear at each floor, for commercial and industrial buildings.
BBT goes beyond what cables do
Cables were traditionally used to move current. BBT does that and also distributes it.
Cables
- Transport current from one point to another.
- Need separate distribution boards at each floor.
One system, more done
- Transports current from one point to another.
- Taps off power to switchgear for further distribution using tap-off boxes.
- Serves as a distribution panel at different stages, such as the floors of a building.
- Continues as a single system that replaces cables as well as distribution boards at floor level.
| Point | Cables | Busbar trunking |
|---|---|---|
| Distribution at each floor | Separate distribution boards | Tap-off boxes on the trunking |
| Installation | Cable laying, trays and terminations | Factory-made modular lengths joined on site |
| Adding a load later | New cable run and termination | Add a tap-off box at the next point |
| Layout | Many cables per feeder | One compact run per feeder |
Five types, from 25 A to 6300 A
Each bar shows the current rating on a log scale. Select a type to read its rating, or enter your current to see which types cover it.
Power BBT
Rated current range.
Size your trunking run
Enter your load to get the design current, the matching BBT type and a ready-to-send enquiry.
Indicative sizing only. Final rating is confirmed by our engineers after reviewing the project.
Every part of a trunking run
Select a part, or click it in the diagram, to see where it sits in a typical run from the transformer to the floors.
Select a part to highlight it.
A busbar trunking system consists of
Unit types
- Transformer feeding unit
- Fire barrier
- Feeding unit to DB
- Straight trunking unit
- Junction unit
- Tap-off unit
- Accessories for mounting
The diagram is a simplified illustration, not to scale.
Pick the type by the job
Choose an application to load it into the sizing tool.
High-rise & commercial
Risers and floor-by-floor tap-offs in towers, offices and malls.
Power BBT · 100–6300 ALighting lines
Light-duty runs for lighting in large halls, warehouses and plants.
Lighting BBT · 25–40 AFactory machines
Power points along production lines and machine bays.
Machine BBT · 40–63 AMoving tools
Trolley-fed supply for cranes and mobile equipment.
Trolley BBT · 35 AHarsh conditions
Cast resin trunking with an IP 67 protection rating.
Cast Resin BBT · IP 67Common questions
What does a tap-off box do?
It takes power from the trunking at a chosen point and feeds switchgear for further distribution, for example at each floor of a building.
Can BBT replace distribution boards at floor level?
Yes. The trunking serves as a distribution panel at different stages, so one system replaces both the cables and the floor-level boards.
Which type do I need for a main feeder?
Power BBT covers 100 A to 6300 A. Use the sizing tool above to see your design current and the type that covers it.
Which brands do you supply?
Legrand, Siemens and EAE Elektrik.
What should I send for a quote?
Your load, voltage, number of floors and run length. The sizing tool builds this summary for you.
Brands we supply
Busbar trunking systems from Legrand, Siemens and EAE Elektrik.
Planning a building's power distribution?
Tell us the load and the floors. We will recommend the trunking type and rating.