According to the New South Wales Department of Primary Industries safety alert issued on Friday, the incident occurred when an electrical worker received a shock while conducting testing on an 11kV cable network.

The qualified high-voltage level two worker reached for the voltage control knob to make a fine adjustment of the output voltage of a high-voltage battery-powered test set when an electrical discharge occurred from the test unit to the worker. The test voltage at the time was 10kV direct current.

At the time of the accident, the test set had reached a stable voltage and the cables under test were charged with stored energy that discharged through the victim to earth. The stored energy was capable of inflicting a lethal electric shock.

The injured worker was transported to hospital for medical testing and was given a 12-lead ECG test and four hours of observation, before being discharged and resuming normal duties.

The test set used in the incident had only recently been delivered to the mine and was being used for the first time. When it arrived at the mine it had been inspected and commissioned.

However, the electrical worker connected the test set in reverse to the operating instructions and did not use the earth connection on the test set.

The DPI investigation found the manual was not specific to the test set supplied and contained information that was intended for a different model; plus the marking and colour of leads was different to convention used on other types of test set.

DPI also found the test set was placed into use without the benefit of product training from the supplier.

The department said to avoid a similar accident, mines should conduct a risk assessment to identify hazards associated with the use of high-voltage test sets. The control measures should be determined in consultation with test set suppliers and competent persons.

It noted the manufacturer’s information should be supplemented by activity-based safe work practices and procedures developed onsite in consultation with the test set users and supplier.

DPI said particular attention should be given to the basics: electrical workers should be trained and authorised to use each type of high-voltage test set at the mine; connection diagrams should form part of training and user documentation; leads and earth terminals should be clearly identified; earth connections to the test set should be applied first and removed last; and security provisions should be applied for the storage and transport of each test set to prevent unauthorised access.

According to the Coal Mine Health and Safety Regulation 2006 Clause 19, an electrical engineering management plan requires that a coal operation must make specific procedures for the use of electrical test instruments.

DPI recommended all mines that reticulate high-voltage electricity should develop, implement and review specific procedures for the use of electrical test instruments on high-voltage equipment.