Updates to NFPA 70E in 2024

A look at some of the main changes made in the new edition of NFPA 70E.

Introduction

In May 2023 the NFPA published the new edition of NFPA 70E, the Standard for Electrical Safety in the Workplace used throughout industry in the United States and often referenced elsewhere, particularly for arc flash safety.

The early publication date is indicative of the fact that there were few major changes made to the document this time, and that no comments (known as Notice of Intent To Make A Motion (NITMAM) in the NFPA world) were received as part of the 2024 edition's review cycle.

This article presents a selection of the most significant changes to the document made for the 2024 edition.

Whilst NFPA 70E is not enforceable in the UK, it does contain "good practice" content related to electrical safety in the workplace, and has particular relevance to arc flash risk management. Many sites will refer to it within their own approach to electrical safety, particularly those with American parent companies.

Global Changes

There are some changes that have been made throughout the document. These reflect updates to the style guide and efforts to be more precise with language. Examples of these changes include:

  • The term Shock has been changed to Electric Shock throughout.
  • All Articles within NFPA 70E 2024 now have a Scope at the beginning - the .1 of each Article. This has resulted in re-numbering and re-structuring of some articles which previously didn't have a separate scope.

Changes to Definitions

All definitions have been consolidated into Article 100 at the beginning of NFPA 70E.

If a definition applies to only one article then the definition will be followed by the applicable article in parentheses. Such definitions typically apply to the more specialist equipment covered in Chapter 3, such as batteries, capacitors and lasers. For example: "Discharge time: The time required to discharge a capacitor to below electrical hazard thresholds. (360)"". This definition only applies to Article 360, the Article on Safety-related requirements for capacitors.

Some definitions now include a "human term" to help with electronic searching when you are using the PDF copy of the document. For example: the definition Boundary, Arc Flash is followed by the more natural term Arc Flash Boundary.

Change to Article 110.2 - Electrically Safe Work Condition

As an Exception to the requirement to establish an Electrically Safe Work Condition, normal operation of electrical equipment is permitted when a "normal operating condition" exists. NFPA 70E previously defined six requirements to determine whether such a condition exists. In the 2024 edition an additional item has been added. The full list now reads:

  1. The equipment is properly installed
  2. The equipment is properly maintained
  3. The equipment is rated for the available fault current
  4. The equipment is used in accordance with instructions included in the listing and labelling and in accordance with manufacturer's instructions.
  5. The equipment doors are closed and secured
  6. All equipment covers are in place and secured
  7. There is no evidence of impending failure

The third item is new for 2024. Ensuring equipment is rated for the available fault current is something typically done at the design and specification stage. It is important to recognise however that changes to the electrical system, both internally and externally, can lead to fault current changes. If the fault current increases, then the Duty Holder has an obligation to verify that existing equipment remains suitably rated for the duty. This is particularly applicable to industrial settings where additional motors, generation (CHP co-generation or solar PV, for example) or expanded distribution (a new transformer) might all result in fault current changes.

The change from Equipment Condition to Operating Condition is reflected in other places within NFPA 70E 2024. For example, the second column in Table 130.5(C) has been re-titled to "Operating Condition".

This is very similar to the United Kingdom's Electricity at Work Regulations 1989 where Regulation 5 states that "No electrical equipment shall be put into use where its strength and capability may be exceeded in such a way as may give rise to danger."

If you need assistance with updating a short circuit fault study, or determining whether system changes put your equipment at risk, then please get in contact. We can undertake system modelling and run short circuit studies to understand the impact and recommend changes.

Change to Article 110.3(I)(1) - Job Safety Planning

This article details how a job safety plan shall be completed, documented and what information shall be included. In the 2024 edition the requirement for the job safety plan to include an Emergency Response Plan has been added.

This means documenting what should be done, how it should be done and who should be responsible for doing it if an incident occurs. It's important that an Emergency Response Plan is fully developed and clearly communicated to those involved with the task. With electrical injuries time is a critical factor and it is crucial that the right actions are taken in the event that an incident occurs. All of the hazards, including shock, burns and falls, should be considered

Emergency procedures are referred to in the United Kingdom Health and Safety Executive's ("The HSE") HSG85 "Electricity at work: Safe working practices" as something that supervisors and those in control of work should be communicating to workers.

The HSE provide a poster on dealing with electric shock, but they note that displaying this in relevant places (e.g. a switchroom) is not a substitute for effective first-aid training. See the poster here.

Change to Article 120.6 - Process for Establishing an Electrically Safe Work Condition

This article describes the steps needed to establish an Electrically Safe Work Condition. Step (7) has been updated in the 2024 edition and now reads:

Use an adequately rated portable test instrument to test each phase conductor or circuit part at each point of work to test for the absence of voltage.

The reference to testing at each point of work means that it is not sufficient to test at the point where the isolation is made, but that the point of work must be verified dead. This can help identify situations where the equipment remains energised even after isolation (perhaps due to stored energy or an auxiliary supply that wasn't identified on drawings or labels).

In HSG85, it states: "check that the parts to be worked on or near really are dead, even if the isolation has been achieved automatically through an interlocking system. If it is a three-phase system or equipment with more than one supply, prove that all supply conductors are dead".

Change to Article 130.4(E)(a) - Electric Shock Protection Approach Boundaries for ac Systems

This table defines the Electric Shock Protection Limited and Restricted Approach Boundaries. It has been updated in the 2024 edition to align with the distances defined by OSHA (e.g. in OSHA 29 CFR 1910.269 Table R-3 etc).

The change mainly addresses a previous error introduced by rounding down when converting from imperial to metric. This introduced a possibility of allowing people closer than the minimum distance if metric was used. Now the metric distances have been rounded up so:

e.g. for 151V to 750V the Restricted Approach Boundary changes from 0.3m to 0.31m in metric (both based on a conversion from imperial 1 foot 0 inches, but rounding up rather than down).

Where equipment labels are fitted in the UK they will typically use the metric measurements so Duty Holders should check their existing labels.

Change to Article 130.5(B) - Estimate of Likelihood and Severity

A new informational note has been added to this section stating:

In most cases, closed doors do not provide enough protection to eliminate the need for PPE in situations in which the state of the equipment is known to readily change (e.g., doors open or closed, rack in or rack-out)

This aligns more closely with the IEEE 1584-2018 methodology for calculating arc flash incident energy, which takes no credit for having a door, closed or otherwise. Lab testing of arc flash often shows doors and covers getting completely blown off, and incidents in the field show doors opened or severely buckled by the release of energy.

Change to Article 130.5(G) - Incident Energy Analysis Method

A new Informational Note has been added in the 2024 edition to provide examples of electrical system changes that could affect previously calculated Arc Flash Incident Energy results. The note reads:

Changes that could affect the results of the incident energy analysis include changes made by utilities or other entities, such as transformer sizing, as well as modifications to protective devices or changes to protective settings.

Such changes mean that an Arc Flash Study might need to be re-run before the standard 5 years has elapsed.

If you need assistance with updating an arc flash study, or reviewing whether system changes require updates to the study, then please get in contact. We can undertake system modelling and run arc flash studies to IEEE 1584-2018 to understand the impact of changes made to your system.

Change to Article 130.5(H) - Equipment Labelling

For equipment labelling it has been added that the label shall be of sufficient durability to withstand the local environment.

This is sensible and though less of a concern in dedicated switchrooms or substations, is more problematic if equipment is outdoors, exposed to wind, rain and sunlight, for example.

Change to Article 130.7(C)(1) - Personal Protective Equipment

This Informational Note describes possible risk reduction methods that can be used if the estimated Incident Energy is greater than the arc rating of commercially available arc-rated PPE when there is a need to test for the absence of voltage.

The first part of the Informational Note has been updated and now states:

Use of noncontact capacitive test instrument(s) or a permanently installed metering device(s) in the equipment for indication, before using a contact-type test instrument to test for absence of voltage.

HSG85 states that the use of non-contact devices such as 'volt sticks' is not recommended for proving dead. However, this is an area where the UK guidance lacks specific advise for mitigating the arc flash hazard.

Change to Article 130.7(C)(5) - Hearing Protection

This article now states that:

Employees inside the arc flash boundary shall wear hearing protection.

It recognises that anyone involved in the task and who needs to be inside the arc flash boundary could suffer from hearing damage should an arc flash occur.

Changes to Table 130.7(C)(15)(b) - Arc Flash PPE Categories for dc Systems

Table 130.7(C)(15)(b) has been simplified compared to that in the 2021 edition. Previosuly there was criteria for assessing DC arc flash between 100 and 250Vdc, and then between 250 and 600Vdc. In the 2024 edition the table is now one set of criteria covering a range from 150 to 600Vdc.

The raising of the lower bound for a DC arc flash (100 to 150Vdc) is supported by recent research into the DC arc flash phenomenon and NFPA 70E-2024, in new Informational Note 3 for Table 130.7(C)(15)(b), provides three example papers which demonstrate that arcs are unsustainable at DC voltages below 150Vdc:

  • J.G. Hildreth and K. Feeney, “Arc Flash Hazards of 125Vdc Station Battery Systems”, 2018 IEEE Power & Energy Society General Meeting (PESGM), 2018, pp. 1-5, doi: 10.1109/PESGM.2018.8586181
  • US Department of Energy Bonneville Power Administration Engineering and Technical Services Report BPA F 5450.05, “DC Arc Flash: 125V, 1300 amp-hour battery”, May 11, 2017
  • K. Gray, S. Robert, and T.L. Gauthier, “Low Voltage 100-500 Vdc Arc Flash Testing”, 2020 IEEE IAS Electrical Safety Workshop (ESW), 2020, pp. 1-7, doi: 10.1109/ESW42757.2020.9188336

Change to Article 130.8(M) - Reclosing circuits after protective device operation

The 2024 edition has clarified the wording around when it is permissible to re-energise a circuit after a protective device has activated.

After a circuit is de-energized by the automatic operation of a circuit protective device, the circuit shall not be manually re-energised until a qualified person or persons determines the equipment and circuit can be safely energised.

This recognises the need for a competent person to investigate and understand why a device activated before returning faulty or damaged equipment to service. Doing so without understanding the reason may lead to further issues including equipment damage and injury.

The wording around manually reclosing circuit breakers, or re-energising circuits through replaced fuses, has also been clarified and emphasises that this cannot be done until the fault has been cleared.

Changes in Chapter 3 - Safety Requirements for Special Equipment

There have been various changes made in Chapter 3. This section refers to safety precautions when working with specialist electrical equipment such as batteries, lasers, and capacitors. If your site has this equipment then it is recommended that you familiarise yourself with the relevant sections of NFPA 70E.

New Informative Annex S - Assessing the Condition of Maintenance

This new Informative Annex has been added to provide some guidance on assessing the condition of electrical equipment. This is important when determining whether a "normal operating condition" exists.

The Annex references the updated NFPA 70B which, as of the 2023 edition, has changed from being "recommended practice" to a standard in the United States. NFPA 70B provides a structured approach to establishing and maintaining equipment in an acceptable condition such that safety and reliability are addressed. It makes periodic inspection of electrical equipment a mandatory requirement.

See this article for more information on updates to NFPA 70B.

References

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