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Safety alert over arc welding following electrode shock to worker’s chest

Date: 
Thursday, 26 March, 2020 - 14:45
Category: 
Policy & legislation
Location: 
National News

SafeWork NSW recently issued a safety alert following an incident in which a worker received an electric shock while changing a welding rod as part of electric arc welding.

The initial shock caused the person to fall, and he then received a second shock when the electrode contacted his chest.

The injured worker required resuscitation and hospitalisation for treatment.

The work was being undertaken in a confined space where conditions were hot and humid. The injured person’s clothing was damp with sweat.

The welding power source was capable of a maximum open circuit voltage of 79V AC rms, and a hazard or voltage reducing device was not used.

“You must limit the maximum open circuit voltage in consideration of where the welding will be done,” the alert said.

“Welding in areas of increased risk of electric shock e.g. confined spaces, should be limited to a maximum open circuit voltage of 48V AC rms.”

Furthermore, the open circuit voltage should be further limited to 25V AC rms where the working environment is hot, humid or damp to account for decreased skin resistance. Australian Standard 1674.2 categorises working environments and sets the maximum permitted open circuit voltage for each category.

Furthermore, a voltage reducing device (VRD) will limit the maximum open circuit voltage to a predetermined level.

While an RCD will not protect a person from electric shock from a welding electrode, the RCD is important to protect against faults on or from the primary side of the power supply.

The alert said PCBUs must identify all hazards including electrical and fire hazards and assess the associated risks, and implement effective controls specific for the task and work environment, including:

  • equipment used should be suitable for the work environment and activity. For example, in a confined space and potentially damp situation a VRD should be used to limit the maximum open circuit voltage to 25V AC rms in accordance with AS 1674.2.
  • equipment is inspected, tested and maintained routinely by a competent person. Use a qualified electrician to do any electrical repairs and perform electrical maintenance and testing. Never used damaged or faulty equipment.
  • machine terminals and lead connections are clean and tight - only use welding leads that are fully insulated throughout their entire length with insulated fasteners.

When welding:

  • protect both the electrode lead and the work lead from damage
  • avoid direct contact with the work piece or with any metal in contact with the work piece
  • do not make direct contact with the electrode including when changing electrodes
  • use insulated electrode holders and accessories
  • always wear dry welding gloves when handling equipment that is energised.
  • never attempt to connect or change welding leads before first isolating the power source
  • do not stand on damp ground or in water when welding or perform arc welding when wet or damp
  • work on a well-insulated floor wherever possible and wear rubber insulated shoes.

“Control all confined space risks when welding; including provision of ventilation, provision of a safety observer who can immediately isolate the power and give assistance in an emergency, and the preparation and practice of emergency response plans including rescue of a person from the confined space,” the alert said.