70E, a Changing Standard

If accepted this month by the TCC, the standard should be a much more concise document with a greatly increased amount of usable information.

NFPA 70E, Standard for Electrical Safety in the Workplace, has become a critical part of the safety equation for companies and individuals who work on or near electrical power systems and their components. OSHA has stated in Letters of Interpretation that 70E can be used as a guide for companies seeking to comply with the regulations. In the Federal Register for the new Subpart S, OSHA states, “The Agency intends to extend this commitment by using NFPA 70E as a basis for future revisions to its electrical safety- related work practice requirements and new requirements for electrical maintenance and special equipment.”

That being said, be aware that the 70E Technical Committee has made its recommendations, but it is up to the Technical Correlating Committee (TCC) to approve these changes, which will not happen until June 2008. The TCC could vote to undo the work of the 70E Committee if it desires, so don’t take these changes as gospel until after the June meeting.

One of the issues in using any standard or regulation is that many people will dissect every word and try to find the “true” meaning. If you look at the list of 70E Committee members, you will notice there are no lawyers or law firms listed. We are technical people, engineers and technicians, managers, and supervisors who strive to write as clearly as possible. Sometimes this does not happen. As a member of the Word and Phrase Task Group, I can attest to how we arm-wrestled with “True Meaning.” The current (2004) edition of 70E uses the phrase “on or near” when discussing distances where 70E needs to be applied. Other words that cause issues are “Exposed” and “Live.” This terminology is somewhat subjective because it can be interpreted in different ways by different people.

In 29 CFR 1910.333(b)(1),Working on or near exposed de-energized parts states, “Application. This paragraph applies to work on exposed de-energized parts or near enough to them to expose the employee to any electrical hazard they present.” To my understanding, on or near has no fixed meaning or distance, but is determined by the hazard. This distance can range from a few inches to several feet, depending on the system or circuit being worked. When conducting training at Shermco’s Training Center, we use this definition and work to ensure the attendees, including our own technicians, understand how to make this determination. It’s not easy, because people tend to prefer a concrete definition or distance, as opposed to what one of my students described as a “moving target. ”In actuality, it is and will remain a moving target because the hazards are not static.

The Word and Phrase Task Group came to common ground fairly quickly on several key points:

• Energized electrical equipment can present serious electrical hazards when properly designed, installed, and maintained, even when there are no exposed conductors or parts. This can result from human interaction with the equipment, such as by making or breaking an electrical contact when there are no arc extinguishing structures (arc chutes).

• Equipment that is guarded can become unguarded if covers are removed, distance is decreased, or other activities remove guarding as specified by the NEC conditions of Article 110.27. This is important, especially when using distance as a guard as is done in some installations. If I approach an exposed, energized bus that uses elevation as guarding to within the Limited Approach Boundary, that exposed bus no longer is guarded.

• Energized electrical equipment is not normally a hazard when it is properly designed, installed, and maintained if there is no human interaction with it that could result in failure. There is always a chance that electrical power equipment could fault unexpectedly, but that is not common. There is usually a failure in one of the above requirements.

• PPE may be required even when there are no exposed, energized parts. If a hazard exists, the worker must be protected from it. In the past, NFPA 70E has focused on exposed, energized parts as constituting a hazard: No exposed, energized parts, no hazard. However, the Hazard/Risk category tables in Article 130.7(C) clearly recognize other hazards when parts are not exposed. We wanted to clarify this aspect of working on or near the equipment.

• The hazards of shock and arc flash need to be addressed separately. A shock hazard applies when a person (or object) is within the Limited Approach Boundary and there are exposed, energized conductors or parts. An arc flash hazard exists when a person is within the Flash Protection Boundary when there are exposed, energized parts and can also exist when conducting an activity that could cause a failure of the equipment.

Clarifying Approach Limits
In order to clarify and add to the usability, the task group decided to replace the “on or near” phrasing with specific limits of approach. If the concern were the shock hazard, we used the Limited Approach Boundary. If the concern were arc flash, then we used the Flash protection Boundary. Examples of how the wording could change are in Article 100, Definitions:

“Exposed (as applied to energized parts). Capable of being inadvertently touched or approached nearer than the Limited Approach Boundary by a person. It is applied to parts that are not suitably guarded, isolated, or insulated.” The word “Live” was replaced with “Energized,” and the phrase “Safe Distance” was replaced with the phrase “Limited Approach Boundary.”

In Article 130.1, “Justification for Work,” the wording was changed to:

“Exposed energized parts and conductors operating at 50 volts to ground or greater shall be put into an electrically safe work condition if the employee is working within the Limited Approach Boundary, unless the employer can demonstrate that de-energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Energized parts that operate at less than 50 volts to ground shall not be not required to be de-energized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.” Once again, the word “Live” was replaced with “Energized,” and instead of saying “before an employee works on or near them,” we stated, “if the employee is working within the Limited Approach Boundary. ”We hope this new wording will enhance the usability of 70E and make it easier to interpret.

Changes in Allowed Equipment, New Technologies
Other major changes to look for (if passed by the TCC) have to do with the tables in Article 130.7. I was also on this task group, and we worked hard to simplify the tables. One such change will be the elimination of HRC -1. I don’t know whether anyone actually used this Hazard/Risk Category, but the task group felt that adding a column for Hazard/Risk Category 2* would be more useful than HRC -1.

New tasks and equipment were added to the tables, including infrared thermography and arc-resistant switchgear. The changes made by TIA 70E-04-1, which reduced the short circuit available current in notes 4 and 5 for Table 130.7(C)(9)(a) and the maximum total clearing time in note 5,were voted to be permanent. There will be some additions to allowable equipment, and in Table 130.7(C)(11), the typical clothing systems were revised to concentrate on the arc rating, rather than the number of layers, so newer technologies can be applied to arc flash protective clothing systems.

A lot of time and effort went into upgrading the Hazard/Risk Assessment process in Annex F, which should provide much more guidance in assessing the hazards. One of the biggest changes—if it passes the TCC vote, of course—will be the elimination of Chapter 4 from 70E. The vote on this was nearly unanimous, as the committee felt that the NEC should be used by people wanting this information, rather than using the sometimes reworded version in the 70E.

June will tell the tale as to which of these changes will actually pass the TCC. If accepted by the TCC, 70E should be a much more concise document and contain a greatly increased amount of usable information.

This article originally appeared in the June 2008 issue of Occupational Health & Safety.

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