Other than the transporting of energy from A to B as in transformer to switchboard “goal posts” which is the direct cable replacement, busbar then gives the distribution board some competition. “Decentralized distribution” is the result of a busbar scheme. Why centralize all the production devices in one place when the function of the device is to protect a machine or load, which should be up to 50-100 m away? By loading the busbar in the environment where the power is to be used, each tap-off unit, which contains the protective device, is positioned close to the load, ideally situated to be operated if the load requires disconnection for maintenance or due to breakdown. As only one load is supplied from each tap-off unit, the busbar remains live and functioning correctly while the maintenance or breakdown is dealt with. This relates to reduced downtime and loss of production for the end client. Each busbar can give electrical distribution capability to cover a 6-8 m wide band along the run. Therefore, 1 m of busbar equals 6-8 sqm of distribution coverage, an ideal budgetary tool and design concept for the end client to hear.

In commercial buildings, the thought of cables being used to feed each floor independently from a main switchboard in the basement would be unthinkable and this area is now the domain of rising mains. So now, by laying the rising main horizontally across the building, we now see the applications being switched to industry, retail, hospital, hotels and virtually any other building type. As the busbar is taking the power of various loads along the length of the run standard voltage drop calculations no longer apply. Siemens gives voltage drop figures, normally in the expression of millivolts per amp per metre allowing a simple calculation be made on a given length. The voltage drop figures will vary depending on the power factor of the system and is based on the full rated load flowing and take into account the resistance across the joints. More accurate results are achieved by considering the actual current flowing if it is less than the rating of the bar. In this instance the resistance of the conductors will be lower due to the reduced temperature and thus the resultant voltage drop will be reduced from the catalogue information


In addition to the above, busbar trunking systems offer very low combustive energy as compared to equivalent cable runs. This leads to increased safety in the event of fire.

Satisfying the client

Busbar trunking is the product that gives the flexibility to change the production flow by moving machines, the assurance that shutdowns are kept to minimum by the single isolation of a load and that the protection devices is only meters away from the machine it is protecting. With these attributes the system will still be satisfying the client 20 years later. In conclusion, is busbar a replacement for cable? No, busbar is the solution that ends clients want that replaces cables and distribution boards. A bold statement but in today’s competitive market engineers need to move forward and access the options and not just rest on traditional methods for solutions.