Electricity is different from other forms of hazardous energy, because it is both undetectable by human senses and potentially immediately fatal upon contact. Since we use electricity every day and everywhere in our lives, this requires a broad application of specialized equipment construction methods and safe work practices to prevent serious injuries or death.
All electrical equipment must be installed and used in accordance with manufacturer’s instructions. Equipment shall be approved for use (accepted by the Electrical AHJ) and shall not be modified or used outside of its approval intent. See the Electrical Equipment Safety Program for more information.
Sufficient training is required to safely interact with electrical equipment. Operators must be trained to operate equipment within its design intent and to not defeat engineering controls.
Personnel who service, modify, repair or build electrical equipment must be able to recognize the hazards and establish controls to prevent injury. This personnel is called Qualified Electrical Workers (QEW’s).
The most fundamental aspect of QEW training is the ability to Test Before Touch. Without an innate human sense to detect a hazardous condition, QEW’s must understand how to properly use test equipment to prove an Electrically Safe Work Condition.
Live repair work is considered extremely hazardous and is generally prohibited. Exceptions can be made but require detailed justification and approval by senior management (EEWP – Section 6.6).
Whenever possible, all work performed on equipment will be performed de-energized. In order to prove and maintain de-energization, QEW’s must follow a strict process to establish an Electrically Safe Work Condition. This process involves both Lockout/Tagout and Test Before Touch. Because this is so fundamental to safe electrical work, it is captured in the electrical safety medallion in Fig. 4.1.7.
Some forms of diagnostics require the equipment to be energized while circuit parts are exposed. Only QEW’s with the proper PPE may perform diagnostics.
Some combinations of switching, testing and LOTO can involve significant procedural complexity. In these cases, written work plans are developed, reviewed and approved by knowledgeable parties in advance and executed with formal procedural compliance. Refer to 6.8 for how and when to build an Electrical Safe Work Procedure.
Proper body positioning must be an integral part of both everyday work habits and detailed work planning. This principle is embedded in the shock protection and arc flash protection boundaries, but must also be emphasized in everything from routine switching activities to set up barriers and barricades.
Hierarchy of controls
To prevent and mitigate hazards, controls must be tailored to the work being performed, the risk of harm posed by the work, and the extent or degree of harm that could occur while performing the work. This tailoring of controls to hazards based upon risk is generally referred to as the “graded approach.”
The preferred hierarchy of controls is:
- Elimination or substitution of the hazards: in the design of equipment or apparatus, careful consideration should be made when applying hazardous electrical power to a device. For example, control and interlock circuitry could be designed to operate at 24 VDC instead of 120 VAC.
- Engineering controls: in the design of equipment or apparatus, permanent guarding, enclosing, or insulation of hazardous voltage sources to prevent unnecessary exposure to the operator.
- Administrative controls: implementation of an Electrically Safe Work Condition (Lockout/Tagout), restricted access to qualified electrical workers, and documented safe work plans are examples of administrative controls.
- Personal protective equipment: working on energized equipment while protected with PPE is a last resort.
The tailoring process should include:
- Identifying controls for specific hazards
- Establishing boundaries for safe operation
- Implementing and maintaining controls