FAQ
1. What is the history to Busbar Trunking?
Busbar Trunking has been in Europe for more than 50 years.
It has progressed from derivations of busbar chambers with heavy metal gauge, metal enclosures with bolt-on covers and clamp connections for tap-offs to totally enclosed sheet steel or aluminium casings with either copper or aluminium conductors and plug-in, tap-off outlets, which are fully shuttered and finger protected for increased safety.
2. What does a busbar trunking system consist of?
Busbar trunking is manufactured into totally enclosed, pre-fabricated sections consisting of copper or aluminium busbars with current ratings ranging from 25 up to 8000 Amps. Power is simply tapped-off by plugs or tap-offs positioned at regular intervals. Typically, a busbar system will consist of 3.0 or 1.5 metre lengths, end feed/live end boxes, end covers, and various tap-off units at different ratings and hanging brackets
3. What are the main advantages of using busbar trunking?
Busbar trunking has several key advantages over conventional forms of power distribution including: -
(a) Reduced, on site installation times when compared to hard-wired systems thus leading to cost savings.
(b) Increased flexibility in design and versatility with regard to future modifications.
(c) Increased safety features brought about by the use of high quality, manufactured components, which provide greater safety and peace of mind for specifiers, contractors and end-users.
4. In which applications are busbars being used?
Busbar trunking systems are now being used in a variety of high and low voltage applications including production plants, workshops, assembly lines, warehouses, distribution centres, supermarkets, retail outlets etc.,etc
5. Is it difficult to estimate a busbar installation project?
No! The beauty of busbar is its simplicity from the design/estimating stage through to installation on site. This is because the technical characteristics and price of each component are always known.
Busbar installations require no special tools. The joints, lengths and accessories are simply bolted or screwed together.
The medium and high power systems have double headed torque bolts, which on tightening will sheer when the correct torque has been achieved.
In addition, the fact that busbar is a factory manufactured and tested product, ensures a high quality, safer installation.
6. How do busbar installations compare in terms of cost?
Most favourably. Historically, the material cost of busbar has been a point of concern for electrical contractors.
However, it is short sighted to compare the cost of busbar against that of cable - and not the real cost of a cable installation to include multiple runs of cable, cable tray and fixing, let alone the protracted time and effort of the cable pulling operation. (more: A comparative study between a traditional system (cables) and one realized with busbar trunking systems. (PDF - 2000K) )
The cost of busbar systems has fallen in real terms over recent years. Add to this, the cost saving in installation time - up to 50% less than cable! The reality is that electrical contractors can offer a more competitive bid, at the same time as offering his client a "state of the art" power distribution installation which is infinitely more flexible in use. The installation time for busbar is virtually the same as for installing cable tray - before the installation of the cables! This is obviously a very important consideration in these days of ever tightening completion deadlines.
7. How do busbars operate?
Busbar trunking falls into two categories - distribution and feeder busbar. Distribution busbar distributes power through tap-offs points along the length of the busbar at typically a 0.5 or 1.0 metre centres. Tap-off units are simply plugged in along the length of the busbar to supply a load, (this could be a sub distribution board or in the case of a factory, to individual machines). Each individual tap-off can normally be added to or removed with the busbar live, thus eliminating production down time.
Used vertically the same systems can be used for rising-mains applications, with tap-offs feeding individual floors. (Certified fire barriers are available at points where the busbar passes through a floor slab). The fact that the protection devices (fuses, switch-fuses or circuit breakers) are located along the busbar run, reduces the need for large quantities of distribution cables running to and from installed equipment.
High power feeder busbar takes power directly from A to B. Usually from a power transformer or switchboard to switchboard. This basic configuration is often referred to as "a goal post configuration". However, if a power source is required to be tapped off then it is possible to do this at a joint along the run - another example of the flexibility of busbar.
Both feeder and distribution busbar systems in the medium and high power ranges are available in two forms: (a) the flat spaced configuration where the conductors are either air insulated or have PVC insulated conductors all within an earthed metal enclosure, (b) the sandwich configuration which is becoming the norm at these ratings. Sandwich construction means that the conductors are individually insulated and mounted to form a sandwich of conductors and insulation within the busbar casing. The sandwich construction busbar has very good mechanical strength, gives higher fault level withstand characteristics and has lower volt drop characteristics. This type of busbar is very compact making it ideal for installing into the ever reducing available space which is allowed in the modern building services!
When used for rising main applications, the sandwich configuration negates the need for fire-barriers because there is no air gap within the casing to give a chimney effect, which would allow the passage of smoke and fire.
8. Do busbars have IP ratings?
Most busbars systems have IP ratings up to IP55 which allows their use in difficult environments. However, for extreme conditions such as petro-chemical applications or outdoor applications resin encapsulated busbar is available which gives a rating up to IP68. Resin encapsulated busbar, as the name suggests, is a system where the copper or aluminium conductors are totally encapsulated in an insulating casing of flame retardant, self extinguishing epoxy resin mix, which at IP68 classes it as submersible in water (to defined limits).
9. What are the aesthetic advantages?
Where aesthetics have be considered, busbar trunking can be installed with a natural galvanised, aluminium, or painted finish. Special colours to match switchboards or a specific colour scheme are also available on request.
Another point to remember is that when comparing with cable, busbars are more compact when installed because allowances for large bending radii are not necessary - an important consideration in view of the smaller switchboard rooms now being made available.
10. What are the advantages of using aluminium instead of copper conductors?
There are several advantages to using aluminium conductors over copper for medium to high power applications. Firstly, aluminium is up to 70% lighter than copper making installation of the trunking easier and less expensive. Aluminium is also a good conductor of both heat and electricity making it ideal in certain applications. Aluminium is also far more competitive in terms of price thereby leading to further cost savings in specification and installation.
11. Do aluminium conductors cause any electrolytic reaction with copper contacts and cable?
There are no problems concerning the reaction between copper and aluminium, as all aluminium busbars manufactured by Zucchini are electro-tin plated throughout their entire length. This is achieved by first coating the raw aluminium in zinc, then copper and finally tin-plate. This is a proven system which has been used extensively throughout all the world.
