The complexity of the system normally determines the level of detail planning that is required for system clearing procedures. A simple, single-source, radial supply system may only require opening a single switch or circuit breaker for circuit isolation.
The clearing procedures for even so simple a case, however, should include checking to ensure that no other sources exist and that the correct isolating device is being operated. It is important that all persons who may be exposed to a hazard, as a result of a switching action, be notified prior to the action.
Complex power distribution systems that require several switching steps to isolate a portion of the system require more elaborate clearing procedures. It is necessary to use written switching instructions for systems that may have several sources into an area.
When written instructions are used, a third party, who is familiar with the power system, should review them for errors and omissions. The consequences of learning about switching errors while in the act of switching are usually costly, especially when the wrong portion of the system is accidentally de-energized. It is important that written procedures be shared with all persons who are involved in the switching process.
A single-line diagram should accompany the written switching instructions so that the switch operator can keep track of the progress through the system. A real-time, single-line mimic bus on a very complex system allows for the independent monitoring of the switching process through the system as component status is changed.
Some mimic-bus systems allow the operator to simulate switching of the system off-line, which allows for the detection of possible errors before the actual switching is performed.
The clearing procedures should be completely written, checked, and understood by all persons involved before they are applied to any portion of the power distribution system. The instructions and/or procedures should include a verification that the power has been removed (by live-line testing or other means) followed by the placement of grounds and the locking/ tagging of isolating devices.
ELECTRICAL SAFE PRACTICES PROCEDURE OUTLINE BASIC INFORMATION
Typical outline of an electrical safe practices procedure
-Title. The title identifies the specific equipment where the procedure applies.
-Purpose. The purpose is to identify the task to be performed.
-Qualification. The training and knowledge that qualified personnel shall possess in order to perform particular tasks are identified.
-Hazard identification. The hazards that were identified during development of the procedure are highlighted. These are the hazards that may not appear obvious to personnel performing work on or near the energized equipment.
-Hazard classification. The degree of risk, as deÞned by the hazard/risk analysis, is identified for the particular task to be performed.
-Limits of approach. The approach distances and restrictions are identified for personnel access around energized electrical equipment.
-Safe work practices. The controls that shall be in place prior to, and during the performance of, work on or near energized equipment are emphasized.
-Personnel protective clothing and equipment. The minimum types and amounts of protective clothing and equipment that are required by personnel to perform the tasks described in the procedures are listed. Personnel performing the work shall wear the protective clothing at all times while performing the tasks identified in the procedure.
-Test equipment and tools. All the test equipment and tools that are required to perform the work described in this procedure are listed. The test equipment and tools shall be maintained and operated in accordance with the manufacturer's instructions.
-Reference data. The reference material used in the development of the procedure is listed. It includes the appropriate electrical single-line diagrams, equipment rating (voltage level), and manufacturer's operating instructions.
-Procedure steps. The steps required by qualified personnel wearing personal protective clothing and using the approved test equipment to perform specific tasks in a specified manner are identified.
-Sketches. Sketches are used, where necessary, to properly illustrate and elaborate specific tasks.
-Title. The title identifies the specific equipment where the procedure applies.
-Purpose. The purpose is to identify the task to be performed.
-Qualification. The training and knowledge that qualified personnel shall possess in order to perform particular tasks are identified.
-Hazard identification. The hazards that were identified during development of the procedure are highlighted. These are the hazards that may not appear obvious to personnel performing work on or near the energized equipment.
-Hazard classification. The degree of risk, as deÞned by the hazard/risk analysis, is identified for the particular task to be performed.
-Limits of approach. The approach distances and restrictions are identified for personnel access around energized electrical equipment.
-Safe work practices. The controls that shall be in place prior to, and during the performance of, work on or near energized equipment are emphasized.
-Personnel protective clothing and equipment. The minimum types and amounts of protective clothing and equipment that are required by personnel to perform the tasks described in the procedures are listed. Personnel performing the work shall wear the protective clothing at all times while performing the tasks identified in the procedure.
-Test equipment and tools. All the test equipment and tools that are required to perform the work described in this procedure are listed. The test equipment and tools shall be maintained and operated in accordance with the manufacturer's instructions.
-Reference data. The reference material used in the development of the procedure is listed. It includes the appropriate electrical single-line diagrams, equipment rating (voltage level), and manufacturer's operating instructions.
-Procedure steps. The steps required by qualified personnel wearing personal protective clothing and using the approved test equipment to perform specific tasks in a specified manner are identified.
-Sketches. Sketches are used, where necessary, to properly illustrate and elaborate specific tasks.
WORK AUTHORIZATION - WORK PERMITS FOR ELECTRICAL WORKS
Before beginning any work, particularly in an existing operating facility, a person should receive a request to do the work from the custodian, thoroughly plan the job, review the job plan with the custodian, and obtain permission from the facility manager to proceed with the work.
Some kind of work authorization document is advisable to ensure that everyone who may be affected is aware of what is going on. In addition to approvals, this document could contain a checklist of safety items that should be considered before proceeding with the work.
The work authorization document forces people to think about the safety aspects of the job. This concept applies to all kinds of work, not just electrical.
Again, when performing electrical work in a country other than the U.S., make sure that any laws of the country that may be applicable to the job being performed are known.
Some kind of work authorization document is advisable to ensure that everyone who may be affected is aware of what is going on. In addition to approvals, this document could contain a checklist of safety items that should be considered before proceeding with the work.
The work authorization document forces people to think about the safety aspects of the job. This concept applies to all kinds of work, not just electrical.
Again, when performing electrical work in a country other than the U.S., make sure that any laws of the country that may be applicable to the job being performed are known.
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