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Coex Training

OPERATING HIGH VOLTAGE EQUIPMENT

HV-Switchroom

By Craig Hagan

A question I get asked regularly on the high voltage courses is ‘do I need to use a switching program every time I operate high voltage equipment?’ The short answer is no.

The idea of the switching program is to ensure an isolation is carried out correctly with minimal chances of accidents. If you’re not accessing high voltage equipment, i.e. no one is going in under your isolation, there is no legal requirement for a switching program.

However, if people are going to access high voltage equipment, for example a high voltage motor, then if they’re going to change that motor out, they must have access to the motor terminals, then this is high voltage access. Therefore, the isolation must be carried out according to a switching program, then a high voltage access permit will be issued and must be married up to that switching program.

If you were switching to shut an electric motor down for example, a mechanical fitter can disconnect the gate box, there is no access to the high voltage terminations, then we don’t need to have a high voltage switching program written and used. The isolation can take place by opening a circuit breaker or contactor, making it your isolation point. If high voltage access is required, then you must have the program, it must be racked out and have an earth applied and is to be locked and then an access permit is issued. That’s the difference between the two isolations.

To write a switching program, you must be authorised by your organisation. In a mine site this must come from the mine manager in writing, otherwise if you’re not on a mine site, it must come from a person who oversees the high voltage installation. They will give you the authority to switch and give you access to write switching programs and issue access permits.