Do you know how they test the load rating of a bridge? They drive bigger and bigger trucks across it until it falls, weigh the last truck, then rebuild the bridge. Obviously this isn’t true, but the same line of thought can be applied to switchboards.
How do I know how my switchboard will behave in the event of a catastrophic fault? One way is to send the switchboard to a testing laboratory, and have them trigger fault conditions within board and monitor how everything stands up. Usually you’ll then need to get the switchboard rebuilt – exactly the same as the first one if it passed the tests.
Clearly for every project you can’t have a switchboard built, tested/blown up in a lab, and then rebuilt – the costs and timeframe involved would be colossal.
Type Testing is the solution.
Type testing essentially means running a typical design of switchboard through a series of tests; and then future boards that are built to the same or very similar design can be considered to comply with the same requirements and if tested in the same way would also pass. A switchboard built to this design can then be classified as a ‘type tested assembly’ (TTA) according to Australian Standard AS3439.1. This standard specifies the tests the must be performed.
Custom built but type-tested switchboards are possible by using a type tested enclosure system. Several enclosure manufacturers have developed and tested an enclosure system, enabling switchboard builders to custom build boards for a wide range of applications and industries. For the type tests to be relevant, the boards must be built in accordance with the manufacturers system and design. Often this requires the switchboard builder to undertake training and obtain certification from the enclosure manufacturer.
Type testing will often add significantly to the cost of a switchboard – especially for smaller boards. For larger, high power switchboards, this cost is justifiable. However for smaller boards, where the impact and likelihood of catastrophic failures is low, the benefits often do not justify the extra costs. As long as the board is designed and built to industry standard practices, complies with relevant Australian standards, and is thoroughly tested by the switchboard builder, the risk and impact of catastrophic failures will be minimal.
