Test before touch, warns ESO

Another arc flash injury has prompted the Electrical Safety Office to issue an urgent callout to electrical workers: reset your safety focus and test before you touch. The arc flash burns were caused after an electrical worker failed to test a circuit before working on a switchboard.

The Electrical Safety Office (ESO) is investigating three other serious incidents where electrical workers received significant arc flash burns working on or near energised equipment in a switchboard. The injured workers were either performing electrical testing, working near energised parts or had failed to correctly isolate the circuit before commencing work.

Working in switchboards carries a greater risk of injury due to fault currents and work often being carried out within a confined space.

ESO recommendations

The ESO urges workers to turn off power to the entire switchboard, if possible, even if this means rescheduling work. If live work is required, for example when testing or fault finding, a risk assessment must be conducted. The ESO also stressed that the risks associated with performing work near exposed live parts can be equivalent to those associated with live work. Typical risks include:

• electric shock if exposed energised parts are touched;
• explosion, for example if a metal tool is dropped onto bus bars causing a short circuit;
• exposed high-temperature parts causing burns to bare skin;
• electrical fires induced by allowing moisture or dust to enter electrical equipment.
   

If working near energised electrical parts poses a safety risk, a written risk assessment should be conducted to determine the risk level and decide on appropriate risk control measures. For the risk of arc flash, the risk assessment must consider the level of possible fault current present at the board. The following should be taken into account:

• The physical size of the switchboard.
• The size of the incoming consumer mains.
• High fault current ratings of circuit protection devices.
• The presence of fault current limiters on the switchboard.
• Transformers located near the switchboard.
   

The ESO advises working through the hierarchy of controls to choose the control that most effectively eliminates or minimises the risk of working near energised electrical parts. This may involve a single control measure or a combination of two or more different controls. Under the hierarchy of controls, substitution, isolation and engineering controls are ranked at the same level of protection, ahead of administrative controls and then personal protective equipment.

A safe system of work or safe work method statement for managing the risk of arc flash should include:

• electrically isolating nearby electrical equipment or installation before starting work and ensuring it can’t be reconnected while the work is being carried out;
• using insulated or non-conductive physical barriers to prevent inadvertent contact with energised parts;
• ensuring workers have appropriate knowledge and skills to perform the work safely;
• testing procedures to prove parts are de-energised before work commences;
• ensuring people not required for the work are excluded from the area by use of screens, barriers and signage;
• ensuring workers have tools, test equipment and PPE suitable for the rated level of fault current.
   

Additional consideration should be given to using a safety observer and any legislative breaches may be referred to the Electrical Licensing Committee for disciplinary action.

For more information on working on or near exposed energised parts, refer to:

• The Electrical Safety Code of Practice 2013 — Managing electrical risks in the workplace.
• AS/NZS 4836:2011 Safe working on or near low-voltage electrical installations and equipment.

www.electricalsafety.qld.gov.au

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