NFPA 79 Industrial Machinery - CNC Milling Workshop

The latest release of NEC/NFPA 70 edition 2020 (NEC 2020) has placed a greater emphasis on increasing personnel safety by mandating the use of Surge Protective Devices (SPDs).

From 2014 to 2020, 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.

CNC Milling Machine

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.

In addition, the future NFPA 79 is considering the following changes:

as well as

CNC Mill

Selecting an SPD for CNC Milling Machine

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 CNC Vertical Boring Mills

Location	Equipment	System	Surge Protector Model#	Link
Service Entrance	Main Service Panelboard	480Vac	MDS750E-480D
Branch Panel	Equipment Panelboard	480Vac	${ITEM_LINK#2178948}<-No Item, #2178948 M50-480D-A	${ITEM_LINK#2178948}<-No Item, #2178948
Local Equipment	Control Panel	480Vac Power Input	DS74US-480D
	Power Supply	120-240Vac Power Input	DS72US-230S/G
		24Vdc Power Output	DS220S-24DC
	Control Unit	Ethernet Cat 6A	MJ8-C6A
		RS232	DLA-12D3
		Wireless	P8AX09-6G-N/FF

Types of machines covered by NFPA 79

References