12 September 2007

Electrical Shock Incident

Safety Incident Topic: Electrical Shock Incident
Location of Incident: Kuantan, Malaysia
Date of Incident: 5 December, 2005

Brief Account of Incident
On the 5th of December 2005 about 2 pm, an electrical technician felt a minor electrical shock by a 240 volts AC supply. During the incident, he was installing a small instrument roof and re-routing the pressure switch cable entrance and piping from top position to downward position. He stopped the job and noticed some water trapped inside the cable gland & terminal box. There is no injury to the technician. The incident was reported four days later.

The technician could have been fatally electrocuted or seriously injury

Critical Factors
- Rain water trapped inside the switch terminal block
- Technician rotated the switch with bare hand while the switch was hooked up with 240 volts AC supply

Immediate Root Causes
- Ineffective protection from previous seal (old silicone sealant peeled off) to prevent water seepage into the switch
- Lack of knowledge of hazards present – not aware of trapped water hazard
- Routine activity without thought – normal practices that isolation was not required if work involves only the body of the switch
- Inadequate PPE – technician should protect both hand with glove before touching the switch casing
- Inadequate isolation of process or equipment – 240 volts was not isolated

System Root Cause
- 240 volts supply to the instrument is not favorable design for instrument supply
- Inadequate implementation of PSP, due to deficiencies – as per LOTO procedure, any electrical energy (24 – 240 volts) should be isolated but not in this case as work was carried out on the casing.

Lesson Learned
- No matter how small or insignificant an incident maybe, it should be reported timely so that appropriate measures can be taken.
- The proper power supply should be clearly identified/labeled at site.
- 240 volts AC supply should not be used for instrumentation (budgeted to be changed in 2006)
- All E/I technicians are reminded to be more vigilant about the hazard of any 240 volts AC supplied instrumentation.
- To review the existing LOTO procedure to address the hazards of working with 240 volts AC power supply and its isolation requirements.

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