An electrical tradesman and his fourth-year electrical apprentice were assigned a job at a food production supplier to install additional GPOs and data outlets. The work included upgrading the existing circuit breaker to a combination residual current device and circuit breaker commonly known as an RCBO to comply with the wiring rules 9AS/NZS 3000). A risk assessment took place prior to the job including the completion of SWMS. The tradesman assigned the de-energised work to the apprentice and left the site to attend a Doctor’s appointment. Unfortunately, this delayed his return to site to complete the switchboard work.
In the meantime, the apprentice completed the de-energised portion of the work detailed on the scope. At approximately 3:00pm the apprentice took it upon himself to complete the work and install the RCBO unsupervised. The apprentice did not attempt to isolate the switchboard from supply prior to commencing the installation of the RCBO. He used a cordless screwdriver to unscrew the terminal of the existing circuit breaker. The metal Screwdriver bit and the metallic screwdriver retention portion of the cordless screwdriver caused a phase to earth fault, causing an arc flash which caused the upstream circuit protection device a 160HRC fuse to operate.
Cordless screwdriver used to unscrew the live terminal with clear evidence of damage and carbonisation, caused by the short circuit.
Luckily no injury occurred that day. However, the incident resulted in a production loss for the client and withholding of payment for the work completed by the electrician.
Switchboard showing carbonisation from where the cordless screwdriver came into contact with earth, and non RCD protected circuit breakers requiring replacement.
NECA Life Saving Tips:
- Always Lock and Tag out all energy sources
- Never initiate a skilled task or operate equipment and machinery unless qualified.
- Inly use correct tools and equipment for the job.
The apprentice made a conscious decision to perform the task unqualified. He also bypassed known protocols and his risk assessment hazard controls, SWMS and No Live Work Policy to complete the work so he could go home early.
Although no injury or electrical shock occurred, and the protection devices in place worked to limit the likelihood of a dangerous occurrence, the apprentice decided to take an unnecessary risk by bypassing isolation; administration and PPE controls prescribed for the task, this behaviour can be described as a reckless violation. Subsequently the apprentice’s employment was terminated.
For further information on safe work practices please contact NECA