Home » FAQs » NFPA 79 Requirements: Are Your VFD Cables Compliant?


Table of Contents

  1. Introduction
  2. What is NFPA 79?
  3. Importance of Compliance
  4. VFD Cable Requirements
  5. Shielding and Grounding
  6. Voltage Rating
  7. Conductor Sizing
  8. Cable Marking
  9. Testing and Certification
  10. Installation Guidelines
  11. Conclusion


Variable Frequency Drives (VFDs) are widely used in industrial automation and control systems to regulate the speed and torque of electric motors. VFDs require specialized cables capable of handling the unique electrical and environmental challenges associated with their operation. Compliance with the National Fire Protection Association (NFPA) 79 standard is crucial to ensure the safety and reliability of VFD installations. This article explores the requirements outlined in NFPA 79 for VFD cables, highlighting the importance of compliance and the key factors to consider to ensure your VFD cables meet the necessary standards.

NFPA 79 Requirements: Are Your VFD Cables Compliant

What is NFPA 79?

The National Fire Protection Association (NFPA) 79 standard, titled “Electrical Standard for Industrial Machinery,” provides guidelines and requirements for electrical systems used in industrial machinery. NFPA 79 covers a wide range of topics, including electrical supply and distribution, grounding, control circuits, wiring methods, and safety considerations. Compliance with NFPA 79 is crucial to ensure the safe and reliable operation of industrial machinery, including systems incorporating VFDs.

Importance of Compliance

Compliance with NFPA 79 is vital for several reasons:

  • Safety: NFPA 79 requirements are designed to ensure the safety of personnel and equipment. Non-compliant electrical systems can pose significant risks, including electrical shocks, fires, and equipment failures.
  • Regulatory Compliance: Many jurisdictions require compliance with NFPA 79 as a regulatory requirement for industrial machinery installations. Non-compliance can result in legal and financial consequences.
  • Reliability: Following NFPA 79 guidelines enhances the reliability and performance of electrical systems. Properly designed and installed electrical systems minimize downtime and ensure the efficient operation of machinery.
  • Industry Best Practices: Compliance with NFPA 79 reflects adherence to industry best practices and demonstrates a commitment to safety and quality in industrial machinery installations.

VFD Cable Requirements

VFD cables used in industrial machinery must meet specific requirements outlined in NFPA 79. Here are some key considerations:

Shielding and Grounding

VFD cables must have adequate shielding to protect against electromagnetic interference (EMI) generated by the variable frequency drive. Shielding minimizes the risk of signal distortion and interference with other equipment. Proper grounding of the cable’s shield is essential to provide a safe discharge path for induced currents and to prevent electrical hazards.

Voltage Rating

VFD cables must have an appropriate voltage rating to handle the voltage levels associated with the specific VFD system. Voltage rating is determined by factors such as the maximum operating voltage and the peak voltage generated by the VFD.

Conductor Sizing

Conductor sizing in VFD cables is critical to ensure adequate current-carrying capacity and minimize voltage drops. The sizing should consider factors such as the motor’s current rating, cable length, and permissible voltage drop.

Cable Marking

VFD cables must be clearly marked with the necessary information, including the voltage rating, current rating, and appropriate symbols indicating compliance with relevant standards. Cable markings aid in proper identification, installation, and maintenance.

Testing and Certification

Manufacturers should perform rigorous testing to ensure the performance and compliance of VFD cables. Testing may include electrical performance tests, thermal tests, and mechanical tests. Choosing cables with recognized certifications, such as UL or CSA, provides assurance of compliance with industry standards.

Installation Guidelines

Proper installation practices are crucial for maintaining compliance with NFPA 79. Some installation guidelines include:

  • Proper cable routing and support to prevent damage or stress on the cables
  • Adequate separation and distance between power and control cables to minimize interference
  • Appropriate termination techniques to ensure secure and reliable connections
  • Proper grounding of the VFD system and associated cables
  • Regular inspection and maintenance of the cables to identify any signs of wear, damage, or degradation


Compliance with NFPA 79 requirements is essential to ensure the safe and reliable operation of VFD systems in industrial machinery. VFD cables play a critical role in the performance and integrity of these systems. By adhering to the shielding and grounding requirements, voltage rating considerations, appropriate conductor sizing, cable marking guidelines, and choosing tested and certified cables, you can ensure compliance with NFPA 79. Additionally, following proper installation practices and conducting regular maintenance inspections further contribute to a safe and efficient VFD installation.

When selecting VFD cables, it is crucial to work with reputable manufacturers and suppliers who offer compliant products and provide documentation of compliance. By prioritizing compliance with NFPA 79, you can achieve optimal performance, minimize risks, and ensure the longevity of your VFD systems in industrial applications.

Published On: 2023年7月7日Categories: ,