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Arc Flash

When is the last time you reviewed your Electrical Safety-Related Work Practices at your facility?  Do you have written procedures, training, inspections and enforcement related to your Electrical Safety-Related Work Practices?  Maybe your facility has a verbal policy of “We do not work on anything live”.

Let’s discuss the importance of your facility implementing Electrical Safety-Related Work Practices, including proper PPE selection, in lieu of relying on the “We do not work on anything live” policy.

First, if your company policy is “We do not work on anything live” then management is turning a blind eye to potentially deadly situations.  If employees at your facility ever open an electrical panel or disconnect and expose bare electrical conductors to inspect or use a multi-meter to test for voltage, to name a few examples, then your “We do not work on anything live” policy is incorrect.

Don’t misunderstand me, de-energizing prior to working on electrical equipment is the best way to perform work.  I am a huge advocate and supporter of following OSHA and NFPA 70E which clearly states that all electrical equipment shall be de-energized and placed in an Electrically Safe Work Condition prior to performing working.  OSHA and NFPA 70E only support working on live electrical equipment, with the proper arc flash and electrical shock PPE, if de-energizing the equipment is infeasible due to equipment design or operational limitations (infeasible, NOT inconvenient) OR de-energizing will create an increased, additional or greater hazard.  Interruption of life support equipment is an example of greater hazard.  Let me be clear, the most effective way to protect your employees from electrical hazards is to de-energize the equipment and create an Electrically Safe Work Condition.

An Electrically Safe Work Condition is created by disconnecting the electrical conductor or circuit parts from energized parts, locking and tagging the equipment per company policy and confirming the absence of voltage by testing.  In creating this Electrically Safe Work Condition employees are forced to work “Live”.  When a qualified employee uses a voltage testing meter to confirm the absence of electrical energy this task is considered “Live” work until the confirmation is made.   Since voltage testing is considered “Live” work proper precautions must be made to protect the employee.

As you can see, all facilities should have appropriate Electrical Safety-Related Work Practices which include proper arc flash and electrical shock PPE.  When an arc flash occurs it can produce temperatures up to 35,000ºF (the sun is 9,000ºF) and produces and explosion of molten metal, shrapnel, intense light, sound waves and pressure waves.  This PPE must withstand the appropriate levels of incident energy and may include fire resistant clothing, hard hats, face shields, hearing protection, safety glasses, leather boots, rubber gloves, full body suit, etc.

One way to determine the appropriate PPE is by using Table 130.7(C)(15)(a) for alternating current or Table 130.7(C)(15)(b) for direct current from NFPA 70E 2012 Edition.  These tables will provide a task-based hazard / risk category for particular equipment and voltage.  This hazard / risk category can then be used with Table 130.7(C)(16) from NFPA 70E 2012 Edition, which will identify the PPE to be worn.

Another highly recommended method of determining PPE is to have an arc flash hazard analysis performed at your facility because of its accuracy.  The equipment and task-based tables from NFPA 70E 2012 Edition are based off a predetermined available short circuit current and clearing time.  This is an issue in that your equipment may have a higher current or a lower current and both can result in greater hazards.  For this reason it is strongly recommended to have an arc flash hazard analysis on your equipment to properly identify the incident energy level.  Once the flash hazard analysis is conducted on each piece of equipment it will be properly labeled with all arc flash information including proper PPE.

To conclude I should clear up two questions that you are possibly asking yourself.

Question: Is NFPA 70E an OSHA standard?

Answer: No, but OSHA has deferred to NFPA 70E in a Standard Interpretation Letter dated November 14, 2006.

Question: Is NFPA 70E the law?

Answer: No

Answer to both:  The fact that NFPA 70E isn’t an OSHA standard and isn’t the law does not matter.

Reason:  If you don’t have the proper policies and procedures in place to protect your employees, OSHA will issue your company a citation in the event of an injury or inspection.

The OSHA standard states:

  • Specific safety-related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts1.
  • Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them2.
  • If the exposed live parts are not deenergized, other safety-related work practices shall be used to protect employees who may be exposed to the electrical hazards involved3.

The follow up question to the above OSHA standards is “What are other safety-related work practices?”  Well there are two options. The first would be to implement NFPA 70E 2012 Edition: Standard for Electrical Safety in the Workplace.  The first edition of NFPA 70E has been around since 1979 and is on its 9th edition.  NFPA also publishes the National Electrical Code.  The second option would be to develop your own professional safety related-work practices backed by a creditable source.  The choice here is an easy one.

11910.333(a) Safety-related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts, when work is performed near or on equipment or circuits which are or may be energized. The specific safety-related work practices shall be consistent with the nature and extent of the associated electrical hazards.

21910.333(a)(1) “Deenergized parts.” Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.

31910.333(a)(2) “Energized parts.” If the exposed live parts are not deenergized (i.e., for reasons of increased or additional hazards or infeasibility), other safety-related work practices shall be used to protect employees who may be exposed to the electrical hazards involved. Such work practices shall protect employees against contact with energized circuit parts directly with any part of their body or indirectly through some other conductive object. The work practices that are used shall be suitable for the conditions under which the work is to be performed and for the voltage level of the exposed electric conductors or circuit parts.