Safety training
Control of Hazardous Energies Standard / V5 DRAFT REVIEW - Oct 2025
High Voltage
In this GWO training standard, the term High Voltage is used for voltages normally exceeding low voltage. The exact voltage designation varies globally depending on where you work.
Use of the term High Voltage:
Terms for low, medium and high voltage may be applied in different ways in different geographies and in other working contexts, such as at the electrical distribution and transmission network levels. For example, IEC defines high voltage as a voltage which exceeds 1000 V AC or 1500 V DC., while NFPA 70E and OSHA defines on or above 600V as high voltage working. At the electrical network level, IEC defines high voltage lines as those above 36 kV (36,000 volts), while medium voltage lines are networks with a voltage between 1 and 35 kV (1,000 and 35,000 volts).
Isolation point
An isolation device shall ensure a reliable disconnection or separation from an energy source
In this GWO training standard, the term low voltage is used to refer to voltages less than those defined as high voltage. The exact voltage designation varies globally depending on where you work.
Low voltage
Use of voltage classifications:
IEC defines LV as voltages normally exceeding 50 V AC or 120 V DC but not exceeding 1000 V AC or 1500 V DC between conductors, or 600 V AC or 900 V DC between conductors and earth. According to the ANSI C84.1-2020: low voltage is between 240 to 600 V and medium voltage is 2.4 to 69kV.
Energy source where you know the level of energy (e.g., as part of a circuit, socket, or a hydraulic check/test point)
Live known source
Minimum arc flash PPE
Minimum:
safety glasses
•
• non-melting clothing (including underwear) with long sleeves and long trousers (small parts of melting materials are acceptable but should be reduced to the minimum possible, ideally eliminated, for example elasticated waistbands) • Safety shoes with non-melting materials (acceptable exceptions are the sole and shoelaces)
Pressure fluids
Compressible (e.g., nitrogen) and non-compressible (e.g., hydraulics) fluids under pressure
Pre-task or job briefing (toolbox talk)
Before starting each job, the employee in charge of the job must conduct a job briefing with the employees involved. The briefing must cover such subjects as:
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