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NFPA 79 Electrical Standard for Industrial Machinery (2024)
Metal-Workshop NFPA79-2024
NFPA 79 Industrial Machinery Metal Workshop2024
NFPA 70 Article 670 Industrial MachineryNEC 2023

NEC2023 The latest release of NEC/NFPA 70 edition 2023 (NEC 2023) has placed a greater emphasis on increasing personnel safety by mandating the use of Surge Protective Devices (SPDs).

From 2008 to 2023, the number articles now requiring SPDs has increased significantly for applications ranging from Modular Data Centers, Fire Pumps, Elevators, Critical Power Systems, Dwellings (Dormatories, Homes, Hospitals, Hotels), etc.

Threat to industrial machines

Various codes and standards possess safety interlock criteria including the American National Standards Institute (ANSI) standards and NFPA 79 for Industrial Machinery. However, until now, these standards have only just begun to address the expanding role that surge protection plays preserving the integrity of equipment and, more importantly, protecting the lives of personnel.

A study commissioned by the Fire Protection Research Foundation, “Data Assessment for Electrical Surge Protective Devices”, provides results of a survey of facility managers concerning surge damage. (NFPA 2014) The study shows that 26 percent of facility managers had damage to safety interlocking systems on industrial machines due to surges . The main purpose of these safety interlocking systems is to protect workers and maintenance personnel from contact with exposed live parts and electric shock. Failure of these devices can put personnel at an increased risk of injury.

Computerized-Lathe
CNC lathe

The solution for NFPA 70 and NFPA 79

To make the installation of a Surge Protective Device (SPD) at the industrial machines interlocking safety circuit mandatory which in turn increases the equipments reliability.

[NFPA 70: 2023] Article 670.6 Surge Protection.
"Industrial machinery with safety inter-lock circuits shall have surge protection installed.”
[NFPA 79: 2024] 7.8.1 Surge Protective Devices (SPDs).
*"Industrial machinery with safety circuits shall have SPD(s) to protect against the effects of overvoltages due to transients or switching surges. The type of SPD(s) shall be selected to protect, at a minimum, the safety circuit devices and shall be permitted to be integral to secondary derived voltage sources.

as well as

4.5.2 Electromagnetic Compatibility (EMC).
"Transient suppression, isolation, or other appropriate means shall be provided where necessary to ensure that the expected level of electromagnetic interference or electrical transients in the machine supply circuit(s) or generated by the electrical equipment of the machine does not lead to the loss of the safety-related control function(s) of the industrial machine."

Selecting an SPD for Industrial Machinery

NEC/NFPA 70 require that Surge Protective Devices (SPDs) shall be UL1449 Listed . This means selecting a surge protector is easier than it has ever been. There are only a few choices available for SPDs that are UL Listed for any of the most commonly used surge standards including UL1449 5th Edition, UL497B, and UL497E.

Recommended SPD for Industrial Machines

LocationEquipmentSystemSurge Protector Model#Link
Service EntranceMain Service Panelboard277/480Vac MDS750E-277Y MDS750E-480D
Branch PanelEquipment Panelboard480Vac M50-480D-A M50-A
Local EquipmentControl Panel480Vac Power Input DS74US-480D DS74US-480D

Power Supply120-240Vac Power Input DS72US-230S/G DS72US-120S/G

24Vdc Power Output DS220S-24DC DS220S-24DC

Control UnitEthernet Cat 6A MJ8-C6A MJ8-C6A

4-20mA DLAS-24D3 DLA-24D3 v.2

Wireless P8AX09-6G-N/FF P8AX09-6G-N-FF

Types of machines covered by NFPA 79

Annex C — Examples of Industrial Machines Covered by NFPA 79

SectionTypeDescription
C.1Machine ToolsMetal Cutting
Metal Forming
C.2Plastics MachineryInjection molding machines
Extrusion machinery
Blow molding machines
Specialized processing machines
Thermostat molding machines
Size reduction equipment
C.3Wood MachineryWoodworking machinery
Laminating machinery
Sawmill machinery
C.4Assembly Machines
C.5Material-Handling MachinesIndustrial robots
Transfer machines
Sortation machines
Conveyors and conveying machines
C.6Inspection/Testing MachinesCoordinate measuring machines
In-process gauging machines
C.7Packaging MachinesCarton-strapping machines
Drum-filling machines
Palletizing machines
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Where to purchase Citel SPD's

Standard and Electric Code References for Surge Protective Devices

Title
NFPA 70 edition 2023, Article 670 Industrial Machinery, 670.6 Surge Protection
NFPA 70 edition 2020, Article 670 Industrial Machinery, 670.6 Surge Protection
NFPA 70 edition 2017, Article 670 Industrial Machinery, 670.6 Surge Protection
NFPA 70 edition 2014, “Data Assessment for Electrical Surge Protective Devices”
NFPA 79 edition 2024, Electrical Standard for Industrial Machinery, Chapter 7,
7.8 Protection Against Overvoltages Due to Lightning and Switching Surges
7.8.1 Surge Protective Devices (SPDs)
NFPA 79 edition 2021, Electrical Standard for Industrial Machinery, Chapter 7,
7.8 Protection Against Overvoltages Due to Lightning and Switching Surges
7.8.1 Surge Protective Devices (SPDs)
NFPA 79 edition 2018, Annex C, Examples of Industrial Machines Covered by NFPA79
ANSI C62.41, Low-Voltage AC Power Circuits
UL1449 5th Edition, Surge Protective Devices
UL1449 4th Edition, Surge Protective Devices
UL497B, Surge Protectors for Data Lines and Fire-Alarm Circuits
UL497E, Antenna Lead-in Conductors
IEC 61643-11, Low-Voltage Surge Protective Devices - Part 11: Surge Protective Devices Connected To Low-Voltage Power Systems - Requirements And Test Methods
IEC 61643-21, Low Voltage Surge Protective Devices - Part 21: Surge Protective Devices Connected To Telecommunications And Signalling Networks - Performance Requirements And Testing Methods
IEC 61000-45, Electromagnetic Compatibility (EMC) - Part 4-5: Testing And Measurement Techniques - Surge Immunity Test
CSA 22.2
NOM-001-SCFI, Standard for Electronic Equipment
NOM-003-SCFI, Electrical Products - Safety Requirements
SEMI S22, Safety Guideline for the Electrical Design of Semiconductor Manufacturing Equipment