A Job Hazard Analysis (JHA) for electrical contractor startup of a new electrical switchboard should include an arc flash hazard assessment to comply with OSHA and NFPA 70E safety regulations.

An arc flash risk assessment should be done to identify arc flash hazards, determine the likelihood of an arc flash and potential injuries, determine the severity of injuries, and determine necessary protective measures, including PPE. [1]

The possibility of an arc flash increases when there are exposed energized electrical conductors or circuit parts, or when safe work procedures are not followed. [1]

Factors that may cause an arc flash include:

• Unintentional tool contact with live parts
• A tool dropped on the ground, creating a spark
• Equipment failure due to poor maintenance or improper design
• Use of tools that spark
• Corrosion of contact surfaces
• Loose contacts
• Worn or damaged insulation
• Dust and condensation
• Incorrect installation of conductors
• Incorrect installation of arc-resistant equipment
• Incorrect work procedures [1]

The basic steps in conducting a job safety analysis are:

• Select the job to be analyzed
• Break the job down into a sequence of steps
• Identify potential hazards
• Determine preventive measures to control these hazards
• Communicate the results [7]

Preventive measures include:

• Ensuring conductors and circuit parts are in safe working condition
• Using lower energy equipment or current energy limiting devices
• Guarding energized electrical conductors and circuit parts
• Using arc flash approach boundaries, including barricades
• Increasing the working distance
• Using non-contact instruments or procedures, where possible
• Using non-sparking tools
• Implementing work permits, safe work procedures, and job planning
• Posting signs alerting of the hazards
• Wearing shock and arc flash PPE [2]

Preventive maintenance should include:

• Regular inspection for wear and tear of insulation, corrosion, poor connections, overheated electrical conductors, excessive pitting of contacts, or excessive moisture, water, or ice on the equipment.
• Regular measurements of critical components.
• Routine inspections of circuit breakers and relays.
• Following established maintenance requirements, including a parts replacement schedule.
• Keeping electrical drawings current. [2]

Boundaries are used to limit how close workers should be to the equipment, especially when work is being done. [2]

An arc flash boundary is the distance at which a person without PPE may get a second-degree burn if an arc flash occurs. [5]

Two types of boundaries are:

• Limited approach boundary: the distance from an exposed energized electrical conductor or circuit part a person may approach when a shock hazard exits (if the person is wearing appropriate PPE and are supervised by a qualified person).
• Restricted approach boundary: the distance from an exposed energized electrical conductor or circuit part a qualified person (only) may approach when there is an increased likelihood of electric shock due to electrical arc over combined with inadvertent movement. [5]

The distance of the boundaries will vary and depend on:

• The system present (alternating-current or direct-current systems)
• The voltage range (phase to phase) or the nominal potential difference
• The presence of equipment including fuses, relays, circuit breakers, exposed movable conductors or fixed circuit parts
• The use of devices to restrict inadvertent movement [5]

A qualified person is someone who has been trained in and has knowledge about the construction and operation of the equipment or work methods and is familiar with appropriate techniques, policies, procedures, work permits, PPE, insulating and shielding materials, insulated tools, test equipment, etc. [4]

Workers must know how to select, use, and care for the necessary PPE, and understand the limitations of the PPE. [4]

CSA standard Z462:21 provides two methods to determine the type of PPE required for a specific job:

1. The incident energy analysis 2. The arc flash PPE category [4]

When estimating the likelihood and severity of an arc flash event, consider factors such as the design of the electrical equipment, the presence of an overcurrent protective device, and operating time, the condition of the electrical equipment, and the effectiveness of any maintenance activities. [1]

Table 1 provides task-based examples of exposure assessments. [3]

Sufficient space should be provided and maintained about electric equipment to permit ready and safe operation and maintenance of such equipment. [6]

At least one entrance not less than 24 inches wide and 6.5 feet high should be provided to give access to the working space about electric equipment. [6]

On switchboard and control panels exceeding 6.0 feet in width, there should be one entrance at each end of such boards unless the location of the switchboards and control panels permits a continuous and unobstructed way of exit travel, or unless the work space is doubled. [6]