NEC 2023 Article 409.70 Surge Protection for UL 508A Industrial Control Panels

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 2014 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 (Dormitories, Homes, Hospitals, Hotels), etc. This article will focus on Industrial Control Panels and how they are defined by NFPA 70 Article 409.

What are UL 508A Industrial Control Panels?

UL508A Main
UL508A Industrial Control Panel

As stated by Article 409, Industrial Control Panels, field- and factory-assembled control panels are used for the control and operation of many processes, from a sewage pump station to an industrial process line. Similar in function to motor control centers in some regards, control panels also contain control, overcurrent protection, and power distribution equipment for operation of industrial heating processes, robotics, spray painting and powder coating lines, and so forth.

Scope

This article covers industrial control panels intended for general use and operating at 1000 volts or less. Informational Note: See ANSI/UL 508A, Standard for Industrial Control Panels, a safety standard for industrial control panels.

Article 409.70Surge Protection
Requirement"Safety circuits for personnel protection that are subject to damage from surge events shall have surge protection installed within or immediately adjacent to the control panel.”

Selecting an SPD for Industrial Control Panels per NFPA 70 Article 409.70 (NEC 2023)

CITEL has a range of UL listed, NEC compliant, Surge Protective Devices (SPDs). 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 (AC Power, DC Power, DC PV Power), UL497B (Data Signals), and UL497E (RF). Citel Logo

The Authoriy Having Jurisdiction (AHJ), in the form of the electrical inspector, will carefully consider many factors while determining the fitness of the Surge Protective Device (SPD) for the Industrial Control Panel (ICP) that is being evaluated for NEC compliance. It is critically important to understand the process that inspector will use to evaluate the SPD according to Article 409.70.

Each component will be required to be a UL Listed SPD. For AC power, DC power or PV power, the SPD will be required to be a Type 1 or Type 2 SPD per UL 1449. A UL1449 Type 1 SPD is preferred since it has passed all fault current testing without any upstream overcurrent protection and is therefore tested in a worst case scenario and provides more installation flexibility. The SPD for communication lines and data signals will be UL Listed to UL 497A, UL 497B, UL 497E depending on the connected network.

NEC 2023
Article 409
Section		LocationUL StandardUL SPD TYPESystemPart #Link
409.70
Surge Protection		Installed within
the control panel		UL 1449Type 1120Vac
1-Phase
2W+G
Single Phase		 DS72US-120S/G DS72US-120S/G
120-240Vac
1-Phase
2W+G
Single Phase		 DS72US-240T/NN DS72US-240TNN
120/240Vac
1-Phase
3W+G
Split Phase		 DS73US-120T/G DS73US-120T-G
120/208Vac
3-Phase
4W+G
Wye		 DS74US-120Y/G DS74US-277Y/G
277/480Vac
3-Phase
4W+G
Wye		 DS74US-277Y/G DS74US-277Y/G
480Vac
3-Phase
3W+G
Delta		 DS74US-480D DS74US-480D
409.70
Surge Protection		immediately adjacent
to the control panel		UL 1449Type 1120Vac
1-Phase
2W+G
Single Phase		 M50-120S-A
230Vac
1-Phase
2W+G
Single Phase		 M50-230S-A
120/240Vac
1-Phase
3W+G
Split Phase		 M50-120T-A
120/208Vac
3-Phase
4W+G
Wye		 M50-120Y-A
277/480Vac
3-Phase
4W+G
Wye		 M50-277Y-A
480Vac
3-Phase
3W+G
Delta		 M50-480D-A
120Vac
1-Phase
2W+G
Single Phase		 M50-120S-B M50B-1PH
230Vac
1-Phase
2W+G
Single Phase		 M50-230S-B M50B-1PH
120/240Vac
1-Phase
3W+G
Split Phase		 M50-120T-B M50B-2PH
120/208Vac
3-Phase
4W+G
Wye		 M50-120Y-B
277/480Vac
3-Phase
4W+G
Wye		 M50-277Y-B
480Vac
3-Phase
3W+G
Delta		 M50-480D-B
409.70
Surge Protection		installed within or
immediately
adjacent to the
control panel		UL 497BListed
isolated Loop
Circuit Protectors		RS422 DLA-06D3 DLA-24D3 v.2
RS232
RS485		 DLA-12D3 DLA-24D3 v.2
4-20mA
Current Loop		 DLA-24D3 DLA-24D3 v.2
48Vdc DLA-48D3 DLA-24D3 v.2
Ethernet Cat 6A MJ8-C6A MJ8-C6A
POE+ MJ8-POE-C6A MJ8-C6A
Serial Interface Unit (SIU) 24V DD25-24V
409.70
Surge Protection		installed within or
immediately
adjacent to the
control panel		UL 497EListed
isolated Loop
Circuit Protectors		RF Wireless
Radio		 P8AX09-6G-N/FF P8AX09-6G-N-FF
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10108 USA Today Way
Miramar, FL 33025 USA		Contact us to develop a surge mitigation solution for your application

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