Preventing Unauthorized Access
Guarding Lines and Equipment
29 CFR 1910.269 Electric Power Generation, Transmission, and Distribution
29 CFR 1910.269 Subpart R: Special Industries - Section (u)
29 CFR 1910.333 through .335 Occupational Safety and Health Standards
29 CFR 1910.333 Subpart S, Electrical - Selection and use of work practices
29 CFR 1910.334 Subpart S, Electrical - Use of equipment
29 CFR 1910.335 Subpart S, Electrical - Safeguards for personnel protection
Safely and compliantly enter a substation – reporting in to the employee-in-charge, and checking for any unusual conditions.
Work safely within substations, including: maintaining adequate access; clearly marking (flagging) energized versus de-energized areas; reviewing and field-checking written switching orders; and managing breakers and breaker circuits for safe removal and insertion.
Comply with mandated fencing/signage to block unauthorized entry to substations’ rooms and spaces.
Comply with mandated physical guards/barriers to isolate substations’ energized lines and equipment.
According to the International Labour Organization (ILO), “OSHA has estimated that in the United States an average of 12,976 lost workday injuries occur annually to electric power generation, transmission and distribution employees. They also report that 86 fatalities occur to these workers annually. OSHA estimates that 1,633 lost workday injuries and 61 deaths can be prevented annually through compliance with the provisions of the Electric Maintenance Standard (29 CFR 1910.26).”
To stay safe when working on substations, the first consideration for workers is to follow the Occupational Safety & Health Administration’s (OSHA) rules for entering a substation. Fires and explosions are common dangers in these extremely high-voltage areas, so working with total awareness is the key to getting home safely.
When workers arrive at any substation where they don’t regularly work, they are to report their presence to a site supervisor who, as is often the case, may be working remotely. It is important to get information about any special conditions that could affect safety, like switching activity, crews working nearby, or substation visitors.
Unless they’re working alone, work teams should hold a job briefing about other pertinent information. For example, and at a minimum, supervisors or senior employees familiar with the site should point out energized equipment in or near the proposed work area. They should also point out the boundaries of any de-energized work area.
Before a worker touches a fence or gate, they should look for any abnormal conditions. Examples include damage to the fence or its grounding, or broken insulators, or oil spills.
What’s the big rule to remember when entering a substation? Beware of a silent substation. The worst sound a worker can hear is no hum. This indicates trouble, such as a fault, switching error, open switch or breaker, or damaged switch.
Once workers have entered a substation and set up a workspace that is safe, they should make sure they have enough access and workspace to safely perform work on electrical equipment. Work teams should mark safe work areas that are switched out. When in the house, they are to mark energized areas above breaker systems, and mark any systems under maintenance or construction.
Utility workers must flag grounds and hot busses before doing any work in close proximity to them, and barricade energized areas around the de-energized areas they’re working on.
Once workers have set up the workspace, they should be directed to follow these work guidelines to keep everyone safe:
Review switching orders. Field-check them as they are executed. Also, check equipment status to make sure the switching order is accurate.
When removing or inserting draw-out-type circuit breakers, keep them in the open position.
Also disable the control circuit, so that the breaker can’t be closed while removing or reinserting it
By keeping breakers open and by keeping control circuits disabled, workers prevent lines from becoming energized. This prevents problems downstream, like arcing, sparking, and damage in the breaker itself.
Because substations conduct such high voltages, they require fencing and signage to prevent unauthorized people from entering. Substations must be surrounded by a conductive fence, to keep out inquisitive people (or animals). Substation fences must be grounded, including their gates. This way, if a fence somehow becomes energized, the grounding will protect anyone who touches it.
When expanding a substation, workers must bond the new fencing to the existing fence grid. Similarly, if removing fence sections, workers must maintain the fence’s grounding continuity. Fences must be inspected at least once every three years.
Substations must also have barriers and signage to prevent unqualified people from entering the substations’ rooms and spaces. A substation’s rooms and spaces must be enclosed within fences, screens, partitions, or walls. Entrances to substation rooms and spaces must display “Danger” signs warning unqualified people to keep out. Any newly installed signs should meet current American National Standards Institute (ANSI) standards. Substation rooms must be locked if they are not under an attendant’s observation.
How Must Equipment Be Guarded?
Substations must have appropriately rated guards around all live parts that operate at more than 150 nominal volts to ground, if they lack an insulating covering. OSHA provides an exception for live parts whose location gives adequate protection against accidental contact.
Within a substation compartment, workers must guard energized parts during operation and maintenance. OSHA provides an exception for fuse replacement and “other necessary access” by qualified workers using approved personal protective equipment (PPE). OSHA requires guards around exposed live parts operating at these voltages to ground that are located within 8 feet of the floor or other working surface. OSHA normally requires guards around live parts operating at these voltages, to phase or to ground.
Purchase the Specialty Courses individually.
You can purchase this course in the following ways:
Library Group Level
Click here to add your own content, or connect to data from your collections.
Monthly or Annual
98% would recommend