Surge protection now mandatory in 2018 revision of NFPA 79

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It should be obvious that machine builders who export their products to North America are subject to the laws and regulations applicable there; one of the most important technical standards relating to machines is the 2018 revision of the NFPA 79 standard.

Surge protection now mandatory in 2018 revision of NFPA 79NFPA 79, the Electrical Standard for Industrial Machinery, is a safety standard developed and published by the USA's National Fire Protection Association (NFPA). It contains requirements concerning electrical safety of industrial machinery. Every industrial machine that is produced in or imported into the USA has to fulfil the requirements of the NFPA 79. If not, it is prohibited from being connected to the power supply network.

The NFPA 79 standard is updated on a regular basis, approximately every three years, with the latest one being the 2018 version that requires surge protection devices in industrial machines containing safety interlock circuits. At this time the 2018 version is only valid in those states that have adopted the 2017 version of the National Electrical Code (NEC), which is greater than half of the USA states.

How can Phoenix Contact help?

With regards to surge protection devices (SPDs), NFPA 79 has some specific requirements:

  • The SPD has to be a UL listed device according to UL 1449
  • Short-circuit current rating of the SPD has to match the short-circuit current at the point of installation
  • The SPD has to be connected according to the installation instructions

In order to satisfy NFPA 79 standards Phoenix Contact has developed the VAL-US range of SPDs that fulfils all of the above and, as a result, facilitates the approval process of inspectors, which is a requirement of the standard to allow a machine to be connected to the grid.

North American grid types, voltages and frequencies are, in part, significantly different to those known in Europe and SPDs need to meet different standards, so using an SPD designed for IEC systems is not good enough. The majority of industrial machines in the USA operate power networks that are not commonly found in Europe, such as three-phase star or delta systems, and the VAL-US range includes SPDs for all commonly used North American systems, with or without neutral connections, and for a variety of nominal voltage ratings.

Although the NFPA 79 standard does not require that surge protective devices for signal and data technology are used, nevertheless, they can be installed in the machines. For example, an SPD to protect the machine communication interface, such as on the control system, would also be recommended.

Follow the link for more detailed information about the NFPA 79 standard and information on selecting the correct VAL-US SPD. To discuss an application in detail, email .

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