Electrical Systems / Industrial Safety / Electrical Safety

The electrical barrier

Are you ready to cross the line?

By Gerald Woodson

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When working on electrical circuits and equipment, your employees who are qualified to perform maintenance on electrical systems have two choices: work on circuits that are electrically safe (locked out and tagged), or work on circuits that remain energized.

OSHA standards and the National Fire Protection Association’s (NFPA) 70E, Standard for Electrical Safety in the Workplace, have specific requirements for working on energized electrical systems. In §1910.333(a)(1), OSHA requires that “Live parts to which an employee may be exposed must 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.”

According to the Bureau of Labor Statistics, in 2007 there were 305 electrocutions by contact with electrical wiring/equipment. There were another 2,420 injuries that required at least one day away from work.

Are your qualified employees fully qualified and prepared to cross over to the energized side of the barrier?

– Gerald Woodson

Locking out and tagging of electrical equipment provides advantages beyond simply shock and arc flash protection. It’s much easier to work on electrical components without bulky personal protective equipment (PPE) such as rubber gloves, leather glove protectors and flame-resistant (FR) clothing. Also, handling tools and test equipment can be difficult when wearing gloves and protectors and can increase the chance of an electrical accident.

If you want your employees to work in the safest electrical work environment possible, you must insist your lockout/tagout program is used for all electrical work. But, if you must consider working on energized circuits, read on.

Establish the barrier

Working on electrically energized systems isn’t the ideal, but on occasion, it might need to be done. With the right approach and appropriate equipment, the work can be done safely.

OSHA requires employers to post safety signs and tags and erect barricades to prevent or limit nonqualified employee access to exposed energized electrical systems. The NFPA 70E has similar wording for signs, tags, and barricades. The NFPA goes further than OSHA by providing specific shock and arc flash approach boundaries for qualified workers.

When your qualified employees cross over to the energized side of the barrier, are they fully qualified and prepared to be there? You should consider four points to ensure they’re ready to go: knowledge, personal protective equipment, hand tools, and test equipment.

Know what you’re doing

Perhaps the best employee protection is knowledge. Before anyone crosses the electrical barrier, they must be trained to do the electrical work. That’s the extent of OSHA’s requirements. However, if they understand your safety program and participated in preparing the electrical work permit, they’ll be best prepared to work on energized electrical equipment.

Training: OSHA’s training requirements for qualified employees are in the Safety-Related Work Practice requirements at §1910.332. These requirements are generalized. Your employees need to know the generalities, but they also need to know specifics of the task.

Electrical safety program: Employees must understand and be able to implement your electrical safety program. The program should contain general program procedures that are required for both deenergized and energized electrical work. The best sources to use for your electrical safety program are OSHA’s Safety-Related Work Practices at §1910.331 through §1910.335, and the NFPA 70E.

Energized electrical work permit: Your employees also must know the specifics of the current job. OSHA is persistent in pointing out that knowledge of specific safety-related work practices is required. Section 1910.333(a), “Selection and use of work practices,” says:

“Safety-related work practices must 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.”

More specifically, §1910.333(a)(2) says:

“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.”

Furthermore, §1910.333(c)(2) says that when work is to be performed on energized equipment:

“Only qualified persons may work on electric circuit parts or equipment that have not been deenergized under OSHA’s lockout and tagging procedures. Such persons shall be capable of working safely on energized circuits and shall be capable of working safely on energized circuits and shall be familiar with the proper use of special precautionary techniques, personal protective equipment, insulating and shielding materials, and insulated tools.”

OSHA requires that specific work practices be implemented to provide a safe work environment for the task being done. The practices must be consistent with the nature and extent of the hazards. However, OSHA doesn’t provide a method to consolidate and implement the specific requirements. One way to supportsafe work conditions is to use an energized electrical work permit. The permit to work on energized electrical systems puts workers, supervisors, and managers on the same page. With the work permit, everyone has knowledge of the task, the appropriate PPE, the specific procedure, and other important requirements. The NFPA 70E provides an example of a comprehensive work permit.

Put on the PPE

Once your employees are mentally prepared to cross the electrical barrier, they need to focus on physical protection. Employees must wear personal protective equipment (PPE) selected specifically for the electrical hazards they will encounter. In §1910.335(a), “Use of protective equipment,” OSHA requires that:

“Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed.”

Requirements for electrical protective equipment are published in Subpart I, “Personal Protective Equipment.”

Shock protection: Unfortunately, Subpart I only provides for rubber protective equipment for electric shock.

Arc flash/blast protection: OSHA does discuss arc flash/blast protection in §1910.335(a)(1)(v). The requirement is:

“Employees shall wear protective equipment for the eyes or face wherever there is danger of injury to the eyes or face from electric arcs or flashes or from flying objects resulting from electrical explosion.”

OSHA leaves it up to the employer to determine how to properly protect employees from arc flash/blast hazards. An excerpt from an OSHA Letter of Interpretation (LOI) dated 11/14/2006 says:

“OSHA's present requirements in Subpart S, Safety-related work practices, are based on NFPA 70E-1983, which did not at that time include specific provisions for flame-resistant (FR) clothing [protective equipment]. Although more recent versions of NFPA 70E have included such body protection provisions, OSHA has not conducted rulemaking proceedings to update Subpart S by adopting comparable provisions specifically related to the use of FR clothing to protect against arc-flash hazards. OSHA's existing Subpart S, therefore, does not include a specific requirement for the use of FR clothing.”

Determining how to provide arc flash/blast protection can be a daunting task. If you follow the NFPA 70E, you have to determine the incident energy of the circuit. Incident energy is the amount of thermal energy, in calories per centimeter squared (cal/cm2), that will impinge on an employee if they experience an arc flash/blast. The number of variables, such as the distance the employee is from the arc event, short-circuits current, arc current, and clearing times for protective devices make the calculation a task reserved for electrical engineers. However, the 70E also provides tables that can eliminate the need to do an incident energy analysis.

Selecting the appropriate FR-rated clothing isn’t easy, but is necessary to protect employees fully. Face protection, gloves, footwear and head protection appropriate to the electric power involved also are required.

Use insulated tools

Using uninsulated hand tools is one potential cause of an arc flash. They also can provide a direct short to ground. The OSHA requirement at §1910.335(a)(2) for insulated hand tools states:

“When working near exposed energized conductors or circuit parts, each employee shall use insulated tools or handling equipment if the tools or handling equipment might make contact with such conductors or parts. If the insulating capability of insulated tools or handling equipment is subject to damage, the insulating material shall be protected.”

OSHA provides additional information for insulated hand tools in a Letter of Interpretation, dated 5/20/1996, which says, in part:

“Wearing rubber insulating gloves when using an insulated hand tool may be appropriate for a particular work application. For example, if an employee's hand is exposed to contact with energized parts other than the one being manipulated with the tool, rubber insulating gloves would be required. Other PPE which provides for the electrical safety of the qualified person may also be used.”

The NFPA 70E provides a table to help determine when rubber insulating gloves and insulated and insulating hand tools should be used, depending on the task being performed and the voltages involved.

Know your test equipment

To be fully prepared to “cross the barrier,” your employees must be skilled at using appropriate test equipment. In §1910.334(c), “Test instruments and equipment,” OSHA points out that:

  • Only qualified persons can test electrical circuits;
  • Test instruments and associated leads, cables, and probes must be visually inspected before being used; and
  • Test instruments must be rated for the circuits to be tested.

Using equipment that’s not rated for the circuits to be tested, or not having multimeters set at the appropriate settings, can pose an arc flash/blast hazard. In a 6/22/1998 Letter of Interpretation, OSHA says:

“Whether an employee needs to wear rubber insulating gloves while working with test equipment on energized circuits will depend on several factors including:

  1. Whether the probes are designed so that the employee's hand can slip off the end of the insulated handle, and
  2. Whether there are other exposed energized parts that the employee's hand might contact during testing.

If either of these conditions is present, the use of rubber insulating gloves or other electrical protective equipment would be warranted.”

Get it done

You know your employees are trained to do the job. They’re also familiar with your company’s electrical safety program. However, that’s not enough. Your employees also need to use the knowledge and apply it to the specific task at hand. Implementing an energized electrical work permit system and conducting a job briefing will address the specifics of the job. Going over each step of the work permit with your employees ensures that they’re wearing appropriate personal protective equipment and have the correct insulated hand tools and test instruments. Taking these steps ensures that your employees are ready to work across the electrical barrier.

Gerald Woodson is an editor at J. J. Keller & Associates Inc., Neenah, Wis. Contact him at (920) 727-7267 or gwoodson@jjkeller.com.