Advances in shock protection and evolving electrical codes
The potash mining industry is crucial for global agriculture, providing essential nutrients for crop production. However, the industry faces significant safety challenges, particularly concerning electrical hazards. This article explores recent advances in shock protection, focusing on the use of Special Purpose GFCIs (SPGFCIs) in mining operations. Additionally, we will discuss the latest updates to the CSA M421 Electrical Mining Code and other changes in Canada’s electrical standards aimed at enhancing worker safety.
Complex industrial loads require a more advanced form of shock protection
Electrical safety in potash mining is paramount, given the harsh and often unpredictable underground environment. As loads and system voltages increase, the shock hazards are just as prevalent, and costly, as they are for smaller 120V circuits. While shock protection used to be limited to 150V single-phase loads, three-phase loads up to 600V can now be protected with the introduction of the Littelfuse Shock-Block®. These SPGFCI devices are designed to provide sensitive ground-fault protection, as well as ground-check protection, required in Canadian mining operations to meet the CSA M421 Electrical Safety Standard.
Case Study: Potash mine shaft sinking
During the sinking of the potash shaft for a major mining company, they used a Galloway to provide a multi-level platform for workers to operate equipment and work on the shaft wall. These workers were in close contact with electrical equipment in a rough and potentially wet environment. Welding is one activity involving the use of equipment connected with a portable power cable to couplers on the various levels of the Galloway. After being made aware of the Shock-Block GFCI technology for these industrial voltages, Shock-Block devices were employed to enhance the safety of the welding operations. These devices measure ground-fault currents and interrupt the electrical circuit before a worker can receive a harmful shock. In addition, Class C, D, and E GFCIs include a ground monitoring circuit, which ensures a proper grounding circuit is in place before the circuit can be energized in the first place. The use of Shock-Block technology significantly reduced the risk of electrical accidents, ensuring a safer working environment for miners.
The adoption of the Shock-Block underscores the safety culture that exists in this company and the industry. To learn more, visit Littelfuse.com/ShockProtection.
CSA M421 Electrical Mining Code
The CSA M421 Electrical Mining Code is a critical standard that governs electrical safety in mining operations in Canada. In 2023, the code updates reflect practical issues experienced in the field and aim to address the evolving needs of the mining industry.
One example is new text related to calculating the touch potential, which is the voltage that someone could be subjected to when touching the metal frame of equipment with a fault inside. This update aligns with the practical challenges faced in larger mining operations, where the scale and complexity of electrical systems have increased.
An important system design parameter contained within CSA M421 code is the use of high-resistance grounding (HRG) systems. HRG systems limit the resulting fault current when there is a phase to ground fault, significantly reducing the risk of arc flash incidents, while still allowing protection devices to measure the current and quickly deactivate the faulted equipment.
NGR monitoring
The grounding resistor used in these systems becomes a critical component, as an open resistor will change the system to be ungrounded, and the normal ground-fault protection will not operate. For this reason, CSA M421 has long required continuous monitoring of the neutral-grounding resistor (NGR), and system de-energization when an open resistor is detected. This is another example of the commitment of the mining industry to employ advanced technologies to ensure system reliability and safety.
Following in the footsteps of the mining industry, the Canadian Electrical Code added requirements for monitoring of NGRs starting with the 2018 edition. This marks another step forward in electrical safety, as it is now applicable to all applications and industries across Canada that follow the Canadian Electrical Code.
Conclusion
Advances in shock protection, such as the use of SPGFCIs, and updates to electrical codes, including the CSA M421 and other Canadian standards, are crucial steps in enhancing worker safety. As mining operations become larger and more complex, the commitment to safety must remain a top priority. Through ongoing improvements in technology and standards, the potash mining industry can continue to safeguard its workers and ensure sustainable operations.
