Written by Mark Lloyd, Product Manager- Poser Supplies & Surge Protection

Surge protection is now mandatory in accordance with NFPA 79 (2018 edition).
It should be obvious that Machine builders who export their products to North America are subject to the laws and regulations applicable there, and one of the most important technical standards relating to machines is the 2018 revision of the NFPA 79 standard.

What is NFPA 79?
The Electrical Standard for Industrial Machinery (NFPA 79) is a safety standard developed and published by the US-American organization National Fire Protection Association (NFPA). It contains requirements concerning electrical safety of industrial machinery. Every industrial machine which is produced in or imported into the USA, has to fulfil the requirements of the NFPA 79. If not, it is not allowed to be connected to the power supply network.

The NFPA 79 standard is updated on a regular basis, roughly every 3 years, with the latest one being the 2018 version which importantly requires SPDs in industrial machines containing safety interlock circuits. At this time the 2018 version is only valid in those states which have adopted the 2017 version of the National Electrical Code (NEC) which is greater than half of the US states.

How can Phoenix Contact help?
With regards to Surge Protection Devices (SPD), 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 US operate power networks which are not commonly found in Europe such as 3-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.

For more detailed information on the NFPA 79 standard as well as information on selecting the correct VAL-US SPD then please click here.

Contact Mark by email mlloyd@phoenixcontact.com or tel: 07717 335477