In June 2016, an electrician was performing wiring modifications to a low voltage (415 VAC) motor control centre (MCC). The power to the front compartment switchboard had been isolated and the busbars in the rear compartment remained energised.
On removing the doors of the rear compartment to identify control cable core numbers, the electrician noticed that the busbar cover panel inside the compartment was not positioned correctly.
As the electrician touched the cover panel to check if it was secure, it moved and there was an arc flash and blast. He received minor flash burns to his right forearm and left hand. The worker was not wearing personal protective equipment (PPE) that was adequate for the energy released in the arc flash.
The subsequent investigation found that the cover panel had come in contact with fuse-holder bolts protruding from the energised busbars behind the cover panel.
Direct causes
- The loose busbar cover panel was moved, making contact with the fuse-holder bolts protruding from the energised busbars.
Contributory causes
- The busbar cover panel was not secured.
- Moving the cover panel was not in the original scope of work.
- The busbars in the rear compartment were not isolated prior to moving the cover panel.
- The electrician was not wearing PPE that was adequate for the energy released in the arc flash.