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Electrical sub-boards (distribution boards)

Safety Alert
1 March 2016

A worker received an electric shock and suffered burnt fingers when he came in contact with exposed live busbars in a sub-board (distribution board or switchboard).

The sub-board did not have enough pole fillers to cover all live points on the board. The power was not isolated and the door to the live sub-board was left open. A worker in the vicinity, in answering a mobile phone call, lost concentration and inadvertently leant against the live sub-board, sustaining an electric shock injury.

Electrical sub-board installation is common during construction. Electrical work must be performed by qualified and registered people. Appropriate guarding must be in place to prevent other people from making contact with or accessing live parts in sub-boards.

Probable causes

  • the sub-board had exposed live parts due to insufficient pole fillers
  • the door of the live sub-board was left open when unattended
  • distraction (from the mobile phone call) while working near the exposed live parts increased the risk of electric shock injury through inadvertent contact.

An electrical sub-board with insufficient pole fillers

Above: An electrical ‘sub-board’ with insufficient pole fillers

Below: Exposed live busbars in an electrical ‘sub-board’.

Exposed live busbars in an electrical sub-board

Action required

  • ensure that all live parts in sub-boards are fully protected by pole fillers
  • the door of the live sub-board and main distribution board must be shut prior to turning on the power unless testing is being performed
  • a person must move a safe distance away from potential hazards when performing unrelated tasks (like answering a mobile phone call), thereby minimising the risk of inadvertent exposure.