One-Line Diagram
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The One-Line Diagram has many uses and is an invaluable tool when it comes to NFPA 70E compliance. It is the most basic type of electrical print. A one-line diagram shows the relationship of electrical components along just one line, using graphic symbols to indicate the path and components of the distribution system. It provides a fast, easy understanding of the distribution system for multiple uses. It will show ratings and sizes of each part or piece of equipment and circuit conductors will details about each over-current protective device. |
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Comprehensive Arc Flash Study
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A one-line diagram is the typical starting place for performing a Comprehensive Arc Flash Study. It will start with the incoming power supply from the utility and continue to each downstream load. It shows conductor sizes, equipment ratings, fuse & circuit breaker information in detail. This information is used to establish the Flash Protective Boundary and Incident Energy levels at each location along the one-line diagram. |
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Maintenance
| NFPA 70E mandates maintaining accurate one-line diagrams, NFPA 70E Art. 205.2. Keeping one-line diagrams current and accurate is critical for worker safety and effective maintenance of the electrical system. One-line diagrams must be updated any time there are changes inside or outside. By outside we include power company changes. Power Company changes can dramatically affect the available bolted fault current in your distributions system. | |
Lock-Out/Tag-Out aka LOTO
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NFPA 70E Article 120 Establishing an Electrically Safe Work Condition requires identifying all sources of energy. A one line diagram will assist workers and supervisors with identifying electrical energy sources and possible multiple sources of electrical energy. |
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Site Survey
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A Site Survey is necessary to develop accurate one-line drawings for or to update existing drawings. The survey would include: Inventorying and confirming all distribution equipment, confirm loads connected, checking wire sizes, include emergency power systems, verify equipment condition and serviceability. This information is used to produce an AutoCAD drawing. Because it is computerized, making changes will be greatly simplified in the future. A site survey is a requirement of doing a Comprehensive Arc Flash Study. We can include the site survey in our Arc Flash Study or you may do it with others. We provide flexibility and choices for our customers. |
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