2017 NEC Broadens Requirements for Surge Protective Devices

2017 NEC Broadens Requirements for Surge Protective Devices

This piece was originally published in the November 2016 issue of electroindustry.

Kenneth Brown, Director of Engineering, Leviton’s Commercial & Industrial business unit


As evidenced by recent changes to the National Electrical Code® (NEC), implementing surge protection strategies is not simply for economic benefit but for public and personnel safety as well.

Beginning in the 2014 edition of the NEC, and again in the 2017 edition, requirements have been added that call for surge protection to be included in the most critical operational areas of both public and private premises.

In the 2014 NEC, Article 700.8 was added to address the reliability of emergency power systems. It stated, “A listed SPD (surge protection device) shall be installed in or on all emergency systems switchboards and panelboards.”

The NEC defines emergency power systems as systems legally required to automatically supply power to designated loads upon loss of normal power. Examples include emergency power systems typically found in medical care facilities, for emergency lighting, communication, and fire control systems, or for elevators used for evacuation.

The 2017 NEC includes the following three new provisions that broaden the application of surge protection beyond emergency power systems:

  • Article 620.51(E) Surge Protection for Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts and Stairway Chairlifts
  • Article 645.18 Surge Protection for Critical Operations Data Systems
  • Article 670.6 Surge Protection for Industrial Machinery

Public Safety

The close view of an elevator's hoistway

Article 620.51(E) was added to address emergency system loads, such as elevators, escalators, moving walkways, and chairlifts. These are systems that are a matter of public safety. It states, “Where any of the disconnecting means in 620.51 has been designated as supplying an emergency a standby system load, surge protection shall be provided.”

Critical Operations

room with communication and server equipment

Article 645.18 simply states that surge protection is required for critical operations data systems. The NEC defines these as “information technology equipment systems that require continuous operation for reasons of public safety, emergency management, national security, or business continuity.”

Failures to this equipment may not only cause undue financial harm to businesses but may also pose a public safety risk. As such, it is imperative to ensure the integrity of these systems, and surge protection is an important part of that.

Industrial Machinery

industrial factory worker

Article 670.6 addresses industrial equipment with safety interlock circuits. It states that “industrial machinery with safety interlock circuits shall have surge protection installed.”

The concern is that electrical surges may cause the interlocks to fail independent of the machine operation. This could pose a significant safety factor for operators, as the intended safety mechanisms may be disabled unbeknownst to the operator.

Read the November 2016 issue of electroindustry.

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