Best Practices for Racking a Circuit Breaker In and Out
Racking a circuit breaker in and out is one of the riskiest actions taken by an employee when it comes to safety and Arc Flash potential with Low Voltage and Medium Voltage gear. This is especially true when it comes to an aging electrical infrastructure. These critical components have mechanical wear and tear from run life, environment, and utilization. This can cause loose connections, debris and other outside factors to shift an otherwise fixed structure because of the forces involved when moving a large component within the gear. When these situations occur, the interaction with voltages and busbar connections can spark an arc flash incident.
Unfortunately, the process of racking circuit breakers is necessary and will fall into an employee’s job scope when maintenance is required. The best way to mitigate these risks is to have a standard operating procedure (SOP) in place that uses best practices to ensure the employee’s safety comes first. Each manufacturer and type of gear has their own steps required to rack in and rack out a circuit breaker making it necessary that each SOP is written specifically for that manufacturer.
When creating the SOP, follow best practices and safety standards in accordance with NFPA 70E. Here are a few that can be used regardless of the manufacturer or equipment type:
- If possible, remove power from the gear
- Review the proper procedure for racking in and racking out the circuit breaker for your specific gear which can be found in the manufacturers manual that came with your specific piece of equipment.
- Make sure the employee understands the risk present prior to proceeding
- Incident energy level
- PPE required while preforming this action
- Where the Limited Approach Boundary and Restricted Approach Boundary are and to block off these areas with easy to recognize barriers
- Do not stand in front of the gear if you can avoid it
- If you meet resistance while performing the action, do not force it
- If possible, utilize a remote racking mechanism
Reduce the exposure to personnel
As equipment reaches end of life or the option to modernize an existing section of electrical infrastructure arises, consider remote racking options to further reduce the exposure to personnel during this function. Most manufacturers have options to specify new equipment or retrofit existing gear with remote racking options. Remote racking devices, whether it be a tethered pendant station or even a control station in another room like an operator’s computer, permit the insertion and removal of electrical devices while the operator is outside the flash protection boundary. Electrically operated devices, such as motor control and switchgear, can be opened and closed from a remote location, removing the operator outside the arc flash protection boundary.
Having knowledge of when it is safe and what the appropriate boundaries are can help mitigate risk associate with electrical hazards. The elimination of risk will help to prevent injury or bodily harm caused by electrical shock and arc flash incidents.