The safety implications for electrical system design, installation, inspection, testing, maintenance, trouble-shooting and repair are
significant.
In most cases, applicable enforceable codes and standards provide requirements that are the minimum for safety. In order to provide electrical systems and equipment well suited for the owner’s environment and needs, designers and installers must go beyond these minimum requirements to provide systems and equipment that are efficient and adequate for the present and to easily accommodate future changes. There may also be additional safety features that can be incorporated beyond the minimum required by Codes and standards.
In some cases, this publication on Selecting Protective Devices (SPD) for overcurrent protection applications presents solutions that merely meet the minimum Code requirements. For other cases, there are recommended solutions that provide superior safety, reliability and practicality.
Safety in regards to electrical equipment and systems has evolved to mean more than just protecting people and property against shock and fire hazards due to equipment failures. It includes considerations for electrical systems that deliver electrical power to loads vital for life safety and public safety, such as emergency systems and critical power operations systems. In these cases, the code and standard requirements focus on electrical system reliability and power continuity to the loads which are vital for life and public safety.
Another safety prospective is electrical safety related work practices.
Federal regulations mandated by OSHA require owners to provide a safe workplace. This includes workers who must work on or near electrical equipment and systems. The hazards of electrical shock, arc flash and arc blast can be eliminated or mitigated by good design practices, proper installation and maintenance procedures.
Selecting and using overcurrent protective devices (OCPDs) can have a
profound impact on the level of safety an electrical system provides. To
that end, this handbook covers many subjects associated with selecting overcurrent protective devices:
• Fuseology and breaker basics cover how overcurrent devices work, their varieties, ratings and operating characteristics that make them suitable for various applications.
• Power system analysis, covered in Section 4 examines fault currents, selective coordination and arc flash that directly related to electrical system safety and reliability. Specifically covered is this section are the National Electrical Code (NEC®) requirements related to these subjects.
• The impact maintenance, or the lack there of, has on ensuring
overcurrent protective device operation and performance over time is
covered in Section 5.
• Electrical safe work practices focuses on NFPA 70E and OSHA
requirements, and how to ensure worker safety.
• Equipment application and protection deals with applying OCPDs
for various applications, and why some are better suited for use with regards to operation, reliability, electrical safety and reducing or eliminating equipment damage.
Our section on special applications focuses on those considerations unique to protecting data centers, HVAC and photovoltaic systems, and fuses used in hazardous locations.
All the sections described above can stand on their own, but they also interrelate. Taken all together, they will provide a comprehensive understanding about selecting protective devices for reliability, code, standards and regulatory compliance, and, most importantly, safety for people, plant and equipment.
The Electrical Protection Handbook Based on the 2017 NEC® (National Electrical Code) is a specialized guide designed to help electrical professionals, engineers, and contractors understand and apply the safety standards and best practices outlined in the 2017 edition of the NEC. This handbook focuses on electrical protection systems, which are critical for safeguarding people, equipment, and facilities from electrical hazards.
Key Features and Topics
1. Overview of the 2017 NEC®
- The role and scope of the NEC as a safety standard for electrical installations in the United States.
- Major changes and updates introduced in the 2017 edition, including advancements in energy efficiency, renewable energy systems, and arc flash mitigation.
2. Electrical Protection Principles
- Fundamentals of electrical protection, including fault currents, overvoltage, and overcurrent scenarios.
- Importance of protective devices in preventing electrical fires, equipment damage, and personal injury.
3. Protective Devices
- Circuit Breakers and Fuses: Types, ratings, and applications for preventing overloads and short circuits.
- Ground-Fault Circuit Interrupters (GFCIs): Requirements for protecting personnel in wet or hazardous locations.
- Arc-Fault Circuit Interrupters (AFCIs): Applications in residential settings to prevent fires caused by arcing faults.
- Surge Protective Devices (SPDs): Protection against transient voltage surges from lightning or power grid disturbances.
4. Grounding and Bonding
- NEC grounding and bonding requirements for electrical systems.
- Design considerations for achieving effective grounding to minimize the risk of electric shock and equipment damage.
- Ground-fault protection for personnel and equipment.
5. Hazardous Locations
- Guidelines for electrical installations in hazardous (classified) locations, such as areas with flammable gases, vapors, or dust.
- Selection and installation of explosion-proof equipment.
6. Electrical Safety
- Arc flash hazards and the NEC requirements for personal protective equipment (PPE) and safe work practices.
- Labeling and marking requirements for electrical equipment to ensure compliance with safety standards.
7. Renewable Energy Systems
- NEC requirements for photovoltaic (solar) systems, wind turbines, and energy storage systems.
- Protective devices and systems specific to renewable energy installations.
8. Testing and Maintenance
- Best practices for testing and maintaining protective devices to ensure their reliability.
- Periodic inspection schedules as recommended by the NEC and other industry standards.
Importance of the Handbook
The Electrical Protection Handbook serves as a practical resource for ensuring compliance with the 2017 NEC, reducing electrical hazards, and promoting safer installations. It is particularly valuable for:
- Designing and installing protective systems in residential, commercial, and industrial settings.
- Educating professionals on the latest NEC changes and how they affect electrical protection practices.
- Assisting in troubleshooting and maintaining electrical systems to ensure long-term safety and performance.
By adhering to the standards outlined in the handbook, professionals can achieve enhanced safety, operational efficiency, and code compliance in all types of electrical installations.
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