Group, The requirement for surge protection in NFPA 70 (2023): 670.6 goes back to NFPA 79, “Electrical Standard for Industrial Machinery.”
The scope NEC 70 (2023): 670 refers to NFPA 79, as follows: Article 670 Industrial Machinery 670.1 Scope. This article covers the nameplate data for, overvoltage protection for, and the size and overcurrent protection of supply conductors to industrial machinery. Informational Note No. 1: See NFPA 79, Electrical Standard for Industrial Machinery, for further information. Informational Note No. 2: See 110.26<https://link.nfpa.org/publications/70/2023/chapters/1/articles/110#ID000700000283> for information on the workspace requirements for equipment containing supply conductor terminals. Informational Note No. 3: See NFPA 79, Electrical Standard for Industrial Machinery, for information on the workspace requirements for machine power and control equipment. 670.6 reads as follows (2023 NEC): 670.6 Overvoltage Protection. Industrial machinery with safety circuits shall have overvoltage protection. Under NFPA 79: 7.8.1, the requirement for surge protection is as follows: 7.8.1*<https://link.nfpa.org/publications/79/2021/annexes/A/groups/7#ID000790001728> Surge-Protective Devices (SPDs). Industrial machinery with safety circuits not effectively protected from the effects of overvoltages due to lightning or switching surges shall have surge protection installed. Exception: SPDs shall not be required where the risks associated with the effects of overvoltages are mitigated such that the safety performance determined by a risk assessment is met. Enhanced Content The term surge-protective devices (SPDs) has replaced the previously used terms overvoltage protection device, lightning overvoltage suppression, and surge switching overvoltage suppression in 7.8.1, 7.8.2<https://link.nfpa.org/publications/79/2021/chapters/7#ID000790000458>, and 7.8.3<https://link.nfpa.org/publications/79/2021/chapters/7#ID000790001613>. See the definition of surge-protective device (SPD) in 3.3.104<https://link.nfpa.org/publications/79/2021/chapters/3#ID000790001610>. The 2018 edition revised the existing requirement in 7.8.1 to require an appropriate SPD for protection of industrial machinery with safety interlock circuits to correlate with Section 670.6 of NFPA 70<https://link.nfpa.org/publications/70/2020>. Best regards, Don Gies Internal From: Richard Nute <ri...@ieee.org> Sent: Tuesday, November 1, 2022 4:03 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Surge Protection Device required by NEC [External email: Use caution with links and attachments] ________________________________ The NEC 670.6 quote triggers some questions: I wonder why industrial machinery with a safety interlock is required to have surge protection as opposed to machinery that does not have an interlock? Is an “on-off” or “run-stop” control considered a “safety interlock”? Is the “surge” a higher-than-normal power-line voltage or is it an impulse from switching or lightning? Does “effectively protected” mean passing the dielectric (hi-pot) test? Richard Nute Bend, Oregon, USA (Several inches accumulation of snow this morning, but above freezing.) From: Doug Powell <doug...@gmail.com<mailto:doug...@gmail.com>> Sent: Tuesday, November 1, 2022 11:28 AM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Surge Protection Device required by NEC From the 2020 Edition, emphasis is mine. "670.6 Surge Protection. Industrial machinery with safety interlock control devices not effectively protected from voltage surges on the incoming supply circuit shall have surge protection installed." It does not say where this protection needs to be applied, so I assume it can be within the machine or somewhere in machine supply. Also, does the product you are inquiring about fall under the definition of Industrial Machinery, NFPA 79? -Doug Douglas E Powell Laporte, Colorado USA doug...@gmail.com<mailto:doug...@gmail.com> LinkedIn<https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.linkedin.com%2Fin%2Fcoloradocomplianceguy%2F&data=05%7C01%7Cdonald.gies%40se.com%7C2941b6fae766483a408508dabc4414aa%7C6e51e1adc54b4b39b5980ffe9ae68fef%7C0%7C0%7C638029297833795988%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=aTsjPeQTYkClbU2fXAmeM4UidLwnyb9v3wEYHCSB7WI%3D&reserved=0> (UTC -06:00) Mountain Time (US-MDT) On Tue, Nov 1, 2022 at 11:55 AM Brian Kunde <bkundew...@gmail.com<mailto:bkundew...@gmail.com>> wrote: It just came to my attention that section 670.6 of the US National Electric Code 2017 requires a listed Surge Protection Device (SPD) to be on any Industrial Machine that has an Interlock, or I assume any kind of safety function. Is this true? The only information I can find on the internet is from the companies that make and sell the SPDs which can often be very one sided. Is there more to this story that I am missing? Does the Surge Protection have to be listed? Are there specifications for the SPD? Is there a Surge Immunity Test that be used to validate and verify whether an additional SPD is required or not? Thanks, The Other Brian - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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