Questions and Answers
NFPA 70E, Standard for Electrical Safety in the Workplace, consists of ___ chapters; 18 informative annexes; the Foreword to NFPA 70E; and Article 90, Introduction.
3/5
The appointment of the NFPA 70E Committee was announced on January 7, ___.
1976
The 1995 edition of NFPA 70E included the concepts of ___ and the establishment of an arc.
limits of approach
The 2004 edition of NFPA 70E introduced the requirements of ___.
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NFPA 70E Chapter 1 applies generally to electrical safety in the workplace. Chapter 2 addresses safety-related ___ requirements.
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Explanatory material is included in the form of informational notes, which are enforceable as requirements.
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An arc flash hazard is defined in Article 100 as a source of possible injury or damage to health associated with the release of energy caused by an electric arc. An arc flash incident is not likely to occur under normal operating conditions when enclosed energized equipment has been properly installed and ___.
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Arc rating is defined in Article 100, in part, as the value attributed to materials that describes their performance with exposure to an electrical arc discharge and is expressed ___.
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The Informational Note to the definition of arc flash boundary states that the onset of a second degree burn on unprotected skin is likely to occur at an exposure of ___ for ___ second(s).
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An electrical hazard is defined as a dangerous condition such that contact or ___ can result in electric shock, arc flash burn, thermal burn, or ___.
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Incident energy is defined as the amount of thermal energy impressed on a surface, a certain distance from the source, generated during an electrical arc event. It is typically expressed in ___.
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A qualified person is defined as one who has demonstrated skills and knowledge related to the construction and operation of electrical equipment.
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An unqualified person is defined as a person who is not a qualified person.
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Which of the following are among the NFPA 70E requirements related to qualified person training?
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The electrical safety program must identify the principles upon which it is based.
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Working where electrical hazards exist is prohibited while alertness is recognizably impaired.
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Personal protective equipment (PPE), such as arc flash protective equipment, is covered in 130.7(C). Other protective equipment, such as insulated tools, is covered in ___.
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Which of the following are required by the 130.7(B) provisions addressing the care of protective equipment?
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In addition to meeting other requirements, which of the following are accurate statements related to the requirements for hand protection used as arc flash protective equipment?
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Several requirements cover the care and maintenance of arc-rated clothing and arc flash suits. Identify which of the following statements are true as they relate to these requirements.
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NFPA 70E requires protective equipment as necessary. Identify which of the following statements are true as they relate to standards that protective equipment must meet.
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In accordance with the requirements in 130.7(C)(15)(a), Table 130.7(C)(15)(a) is to be used to determine which of the following for AC equipment?
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The arc flash PPE category can be determined through an incident energy analysis.
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Which of the following statements are true for tasks performed on energized equipment in panelboards or other equipment rated greater than 240 volts and up to 600 volts within the parameters of Table 130.7(C)(15)(a) when arc flash PPE is required?
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Determination of an arc flash PPE category for a task performed on DC systems is determined from Table 130.7(C)(15)(a).
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Table ? is used to determine protective clothing and PPE to be used when working within the arc flash boundary based on the determined arc flash PPE category. Arc-rated clothing with a minimum arc rating of ? is required for arc flash PPE Category 2.
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The following items would meet the protective clothing and personal protective equipment (PPE) requirements for arc flash PPE Category 2, where there is not a need for an arc-rated jacket, parka, high-visibility apparel, rainwear, or hard hat liner.
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Which of the following is/are categories of requirements of alerting techniques?
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Section 130.9 deals with the requirements for work within the limited approach boundary or arc flash boundary of overhead lines. Which of the following are categories of requirements related to this work?
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Table 130.7(C)(15)(a) is used to determine whether arc flash PPE is required.
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Cutting, removing, or rerouting of conductors is addressed in which of the following sections in NFPA 70E?
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Before cutting or drilling into equipment, floors, walls, or structural elements where a likelihood of contacting energized electrical lines or parts exists, the employer shall perform a risk assessment to _____.
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When it has been determined that a reasonable possibility of contacting electrical lines or equipment exists, ____ shall be used during excavation.
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Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling units and that are likely to require examination, adjustment, servicing, or maintenance while energized must be marked with a label containing both the available incident energy and the minimum arc rating of clothing.
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For the purposes of using the arc flash PPE category method to select PPE, different types of OCPDs, such as MCCB, ICCBs, and LVPCBs, are all considered to have the same 1.5 cycle typical fault clearing time in the Informational Note to Table 130.7(C)(15)(a).
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There are five different common overcurrent protection trip types that a circuit breaker may incorporate. Which type is intended for overcurrents that can persist for many seconds to minutes without damaging the conductors or electrical equipment and is considered overload and low-level fault protection?
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Which type is intended for very high fault current conditions causing the circuit breaker to open without an intentional delay?
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Which type is a newer feature intended to reduce the incident energy exposure if an arcing fault incident occurs while a worker is working on exposed energized conductors?
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Under fault conditions, current-limiting fuses have the ability to limit the current let-through to less than the available fault current and clear the fault current in 1/2 cycle or less.
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Which type of overcurrent protective device is shown in the image below?
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Which type of overcurrent protective device is shown in the image below?
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Which type of overcurrent protective device is shown in the image below?
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NFPA 70E informational Note to Table 130.7(C)(15)(a) has the typical fault clearing time for molded case circuit breakers as 3-cycle with an instantaneous integral trip.
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NFPA 70E informational Note to Table 130.7(C)(15)(a) has the typical fault clearing time for current-limiting fuses as _____?
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Study Notes
NFPA 70E Overview
- NFPA 70E, Standard for Electrical Safety in the Workplace, contains 5 chapters and 18 informative annexes.
- Chapter 1 is divided into 3 articles.
- The NFPA 70E Committee was established in 1976 to assist OSHA in creating electrical safety standards.
Key Editions and Changes
- The 1995 edition introduced arc flash concepts and limits of approach.
- The 2000 edition detailed flash protection boundaries and personal protective equipment (PPE) utilization.
- The 2004 edition added the energized electrical work permit requirement.
- The 2021 edition supersedes all previous editions.
Chapters Breakdown
- Chapter 1 focuses on general electrical safety in the workplace.
- Chapter 2 addresses safety-related maintenance requirements.
- Chapter 3 provides supplementary safety requirements for special equipment.
Arc Flash and Hazard Definitions
- Arc flash hazard refers to possible injury or health damage from energy released by an electric arc.
- An electric arc incident is likely with exposed energized conductors or parts in an unguarded or unmaintained condition.
- Arc ratings determine a material's performance during electrical arc exposure and are expressed in cal/cm².
Incident Energy and Risk Assessment
- ATPV defines incident energy levels that may cause second-degree skin burns, based on a prediction curve.
- The incident energy assessment methodology is crucial for determining risk and protective measures required for electrical work conditions.
- Shock risk assessments are mandatory when employees work near energized conductors.
Electrical Safety Training and Responsibilities
- Employers are obligated to document employee training on safety topics listed in NFPA 70E.
- Responsibilities include developing an electrical safety program that reflects the nature of electrical hazards.
Personal Protective Equipment (PPE)
- PPE, including arc flash protective gear, must cover all ignitable clothing.
- Arc-rated clothing should be used along with insulated tools and rubber insulating gear for protection against accidental contact.
- Employers are responsible for providing and ensuring the proper use of protective barriers and materials for confined spaces where electrical hazards exist.
Working Conditions and Permits
- Energized work conditions are generally prohibited unless specific conditions are met, allowing work within the limited approach and arc flash boundaries.
- An energized electrical work permit is necessary for tasks involving exposed energized conductors not in a safe work condition.
Protective Clothing Selection
- Selection of protective clothing must consider coverage, and outer layers must be made from arc-rated materials.
- Different arc flash PPE categories dictate specific clothing and equipment requirements for various tasks based on risk exposure and incident energy levels.
Additional Considerations
- All employees must be alert and not impaired when working around electrical hazards.
- Regular testing of GFCI devices per manufacturer instructions is required to ensure safety.
Testing and Maintenance
- Electrical equipment must be rated for their respective use and maintained in adherence to NFPA standards.
- Documentation of risk assessments and safety measures are essential for compliance and worker protection.
Summary
- NFPA 70E emphasizes the importance of safety in electrical work, necessitating proper training, protective measures, and compliance with established safety regulations to mitigate hazards and protect workers.### Arc Flash PPE and Electrical Safety Standards
- Arc flash PPE Category 2 does not require specific items such as an arc-rated jacket, parka, high-visibility clothing, rainwear, or hard hat liner.
- Alerting techniques are forms of protective equipment outlined in 130.7, with categories I, II, and IV identified as requirements.
Electrical Work Requirements
- Section 130.9 specifies requirements for work within the limited approach boundary or arc flash boundary of overhead lines, covering categories I through VI.
- Table 130.7(C)(15)(a) does not determine the necessity of arc flash PPE.
Risk Assessment and Safe Work Practices
- Cutting or rerouting conductors is covered in section 130.12 of NFPA 70E.
- Employers must conduct a risk assessment before drilling or cutting in areas where energized lines may be present.
- When contacting electrical lines is likely, appropriate safe work practices and PPE are essential during excavation.
Electrical Equipment Labelling
- Electrical equipment must be labelled with the available incident energy and the minimum arc rating of clothing, though this statement is marked as false.
Overcurrent Protection Devices (OCPDs)
- Different OCPDs like MCCB, ICCB, and LVPCB are not considered to have the same fault clearing time; this statement is false.
- Circuit breakers incorporate five trip types; long-time trip (L) protects against prolonged overcurrents, while instantaneous trip (I) responds to very high fault currents without delay.
- Energy-reducing maintenance switching trip (A) is designed to minimize incident energy during arcing faults, with options for remote activation.
Current-Limiting Fuses
- Current-limiting fuses effectively limit the current let-through to less than the fault current, clearing it in half a cycle or less. This reduces incident energy during arcing events.
- The typical fault clearing time for current-limiting fuses is documented as 0.5 cycles when the fault current is in the limiting range.
Types of OCPDs
- Various types of OCPDs include insulated case circuit breakers or low voltage power circuit breakers, current-limiting fuses, and molded case circuit breakers, each serving unique functions in fault conditions.
NFPA 70E Information Notes
- NFPA 70E informational Note to Table 130.7(C)(15)(a) clarifies that molded case circuit breakers have a typical fault clearing time of 3 cycles with an instantaneous trip mechanism; this statement is also marked as false.
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