Commonly used electrical maintenance terminology questions and answers.
What does anticipating failure mean?
After electrical equipment is installed, it begins to deteriorate. Adequate maintenance extends the life of equipment. However, equipment could fail in service. Frequently, electrical equipment provides warnings that failure is imminent. A worker might note a unusual noise or sound. An unusual smell frequently is a warning signal. Elevated temperature is a warning that a failure is near. Anticipating failure, then, is being cognizant of indication such as these and reacting to them.
When impending failure is recognized, remove the equipment load. Remove the source of energy with upstream disconnecting means. Do not operate disconnecting means that have an unusual smell, noise, or other indication of impending failure.
What is the difference between a barrier and a barricade?
A barrier is intended to provide a physical obstruction and prevent contact with an energized or potentially energized conductor. Barriers normally are used to isolate energized conductors. On the other hand, a barricade is physical obstruction that is intended to serve as a warning.
What is blind reaching?
Workers sometimes attempt to locate or modify a circuit by reaching a hand into a location that is not directly visible, for instance, behind a barrier. Any location that is not in a direct line of sight is a blind location. The best practice is to avoid reaching in to positions when visibility is not complete. Absences of adequate light effectively turn visible locations into blind locations. You should make certain that the intended contact point is adequately lighted and directly visible.
What is meant by the term degree of the hazard?
An incident that results from a hazard could be catastrophic. In slightly different conditions, another incident resulting from the same hazard might cause a small incident. The amount of energy available to the hazard determines the severity of an incident involving the hazard. For instance, each time a disconnecting means is closed into an energized circuit, an electrical arc results. When the arc is associated with a 15 –ampere receptacle circuit, the arc is small. When the disconnecting means is in a 400-ampere circuit, the arc is larger. The degree of the hazard, then, refers to the potential severity of an incident resulting from the condition.
What does duty cycle mean?
Some electrical instruments are assigned a duty cycle that describes the maximum on time and minimum off time. For instance, most solenoid-type voltage testers are assigned a duty cycle of 15 seconds. The period of time in an energized condition must not exceed the duty cycle. After using it energizes the instrument, the device must remain de-energized for at least the same amount of time. The duty cycle defines the maximum time period that the device may be energized and the minimum time period that the device must rest before being used again.
What are electrical safety program controls?
Program controls are those policies that control the actions of each employee. For instance, a program might be based on an expectation that a circuit is considered energized until proven de-energized. A control might include an expectation that every employee is assigned his or her own personal lockout devices. A control might also include an expectation that every circuit is energized until an electrically safe work condition exists.
What is an electrically safe work condition?
An electrically safe work condition refers to equipment and circuits in which all sources of electrical energy have been disconnected, verified as being open, and controlled by locks and tags. An electrically safe work condition exists only after the following six steps have been executed.
- Determine all possible sources of electrical energy by checking-up-to-date drawings, tags, and labels.
- After properly removing the load current, open the disconnecting means.
- Where possible, visually verify that an opening exists in all supply conductors.
- Install locks and tags in accordance with an approved written procedure.
- Verify the absence of voltage on all exposed conductors by checking the voltmeter for proper operation both before and after verifying that no voltage exists.
- Install safety grounds when it can be determined that conductors in the work area could become energized as the result of a static discharge, an overhead line falling, and similar circumstances.
What is an energized work permit?
Consensus and OSHA standards require employers to have an electrical safety program. The program must consist of procedures and policies a workplace that is free from recognized hazards.
One of these procedures must describe an energized work permit, including how to obtain and how to manage the process of generating and executing the permit. The employer’s procedure must define responsibilities associated with the permit. The energized work permit ensures that work tasks that must be performed in the vicinity of an exposed energized electrical conductor receive sufficient attention. Workers making the choice to perform the task while the circuit is energized will have considered the increased potential of injury.
The written permit ensures that supervisory personnel know about the increased risk of injury. It also ensures that workers have the opportunity to say that the risk is unacceptable. When the energized work permit is complete and authorized, supervisors, managers, and workers ll understand that the risk of injury to workers is elevated.
Why is an energized work permit important?
Managers and supervisors may not recognize that employers are executing a task with elevated risk of injury. An energized work permit provides an opportunity to educate managers ( or customers0 about the risks and hazards of a particular job. Requiring a supervisor’s signature ensures that the supervisor understands that an increased risk of injury exists. The written permit provides the supervisor with the opportunity to delay the work until an electrically safe work condition exists. You can find an example of an energized work permit in Annex J of NFPA 70E.
What is a hold card?
In transmission circuits where that disconnecting means is located several miles from the point of work, a hold card is a device that is installed in the disconnecting means for a circuit on which work is progressing. A hold card is a method of communicating a warning that the disconnecting means must not be operated. The details of the hold cars process vary among employers.
What is incident energy?
Incident energy is the thermal energy that contacts (is incident upon) a person’s skin or clothing. Incident energy is defined in terms of heat energy per unit of area. The consensus designation is calories per square centimeter.
What is a job briefing?
A job briefing is a discussion of a work task before it is started. The briefing may be a short discussion of potential hazards or it could be a complex discussion involving several workers or crafts. A job briefing may be known by different names in different organizations. An effective supervisor ensures that a job briefing is conducted at the beginning of each work task and at the beginning of each day.
What is a live part?
The term live part has been used for many years. However, electricians develop different understandings of the term’s meaning. The term I defined in the National Electrical Code and NFPA 70E, and the committees who produce the standards are meticulous to ensure that the term is used in accordance with the definition. Other national consensus codes may not use the same definitions, and workers do not necessarily apply the consensus definition.
Some workers consider that a part must be exposed for it to be a live part. Other workers consider any energized part to be a live part. In previous years, the presence of a hazard was necessary for a part to be considered a live part. The important issue is that a worker recognize if and when he or she is exposed to shock or electrocution. It may be helpful to clarify the understanding or meaning of this term before engaging in work tasks where the term will be used.
What is a moveable conductor?
When a worker approaches an exposed energized electrical conductor, the distance between the work and the exposed energized conductor determines the risk of injury. In cases where the conductor is held in position mechanically and the worker is standing on a solid platform, the worker is in control of the approach distance; the conductor is fixed in position. However, in cases where the conductor moves with the wind or other external force, the worker is not in control of the approach distance; the conductor is moveable. When the worker is standing on a platform that moves, such as a a platform on an articulating boom, the worker may not be in control of the approach distance. The conductor is considered to be a moveable conductor, because the distance between the worker and the conductor might vary beyond the worker’s ability to control it.
What is a procedure?
A procedure is a document that describes how to perform a work task. For instance, a document containing a written step-by-step description of a process to install locks and tags ion switches or valves is a procedure. A procedure might also describe how to perform a safety-oriented task, such as creating an electrically safe work condition, or it could describe how to check out new equipment.
What is a workplace?
A work place is a location where employees are performing work. A workplace is associated neither with the discipline of the employee or the business nor with a product or service. If work is performed at a facility or location, the facility or location is a workplace.
What is a safe workplace?
The general duty clause of the OSH Act requires employers to provide a workplace that is free from recognized hazards. Although the clause suggests that employees must not be exposed to a known hazard, it does not mean that an injury cannot happen. The general duty clause means that employers must exercise normal care and take reasonable precautions to eliminate the risk of an injury. National consensus standards generally define normal and reasonable actions.
What is a work practice?
When workers execute a work task, each discrete step in the process is accomplished either by generating a new action or by repeating actions previously learned. The work might require a series of discrete steps or a few sets of steps. For instance, a worker might protect his or her voltmeter by storing it in a case. Another worker might keep his or her voltmeter loose in a tool box. In one instance, the work practice is a good one and the other not so good. Using a ground-fault circuit interrupter on each cord is an example of a work practice.