Play it safe with medium voltage equipment installations

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Safe medium voltage switchgear and equipment installations are more than just a goal—they’re a necessity. Both employees’ safety and the reliable performance of Medium Voltage equipment depend on safety-related issues being addressed during the early stages of the equipment deployment cycle. A failure to plan for safety during the design and installation processes can cause otherwise reliable designs to be compromised or experience electrical fault issues.

Knowing so much is riding on safety can be overwhelming. Here are some areas that deserve attention to ensure a safe installation. These guidelines focus on building installations but are applicable to many other situations.

Safety event

  • Perform a safety or risk analysis to identify risk factors and determine what protective measures can be implemented to prevent the occurrences. Arcing faults and contact with live conductors or energized parts are the two major situations where failure occurrences are most likely to occur.


  • Focus on the environment both within and surrounding the building. The internal environment can greatly affect the global safety level of the installation and the surrounding physical environment impacts areas such as continuous service conditions and equipment access.


  • Study the specified service conditions of equipment to optimize safety.
  • Define and validate the rated characteristics of the equipment as maximum values because excess leads to the probability of increased risk, if not to immediate failure.
  • Establish a plan to monitor, or to inspect on a regular basis, the installation for assessing the actual service conditions. This mitigates issues caused by external influences that negatively affect equipment performance and contribute to it its failure under some conditions, potentially creating hazardous situations.
  • Consider where and how equipment will be used to ensure it is operated in optimal conditions.


  • Select carefully the type of connection to earth of the neutral point of the power supply. This choice may not be open at the design stage, but it will have a significant influence on installation performance.
  • Prepare a single line diagram. This acts as a blueprint for the electrical system and reveals information about the electrical installation. The diagram also impacts the safety of personnel throughout the installation’s lifetime.
  • Plan for civil work, which will accommodate the medium voltage portion of the installation. Two serious issues that need to be focused upon are risk of fault occurrence and risk of personal exposure.
  • Ensure all electrical characteristics of equipment incorporate a built-in margin vis-a-vis the real (forecasted) operating condition.

Operational Decisions

  • Determine expected performance criteria and expectations for a site’s operation prior to design. This information becomes an important input for defining design constraints and should guide decisions that affect personal safety.
  • Define service continuity at several levels based on the criticality of the application and of the connected loads.
  • Create a maintenance policy and maintenance procedures. Take into account factors such as manufacturers’ recommendations for equipment and individuals’ designated responsibilities.
  • Establish work procedures.
  • Ensure workers’ safety by providing a clear explanation of risks that clarifies why safety equipment is recommended or required in some situations to prevent incidents.
  • Supply the appropriate tools for tasks.
  • Provide relevant, consistent training for employees.

Safe medium voltage installation is achievable if you take a structured approach beginning with initial design. See my white paper called How Medium Voltage Equipment Performance and Reliability Depend on Early Safety Considerations to learn more about the topic and for more detailed guidelines.

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