There is some specific requirements on single line diagram or SLD in NFPA 70E standard. An up to date SLD must me maintained and readily accessible to employee or worker.
In simple word Single Line Diagram is the complete flow of electrical circuit with information like components(protection, switching, interlocks etc) with clear data (cable size, connected load etc). Now the question is whether to maintain a single diagram is mandatory in an Industrial sites. And if so is there any criteria on which SLD would be maintained.
Some facts of maintaining a Single Line Diagram
In case of an existing single line diagram three question can be asked as such below-
- Is the Single line diagram up to date?
- Is the single line diagram is authorized by a proper body or person?
- Is the Single Line Diagram available to the related employee for maintenance, operation or servicing?
You see these three questions are important because a misleading single line diagram is critically
International Standards about Single Line Diagram
There is some direct requirements of maintaining updated or as built Single line diagram authorized by a competent body and available on site to employee.
The NFPA 70E(Standard for Electrical Safety in the Workplace, 2004 Edition) has cover this all requirements relating to single line diagram.
01In NFPA 70E [Definition of Single Line Diagram]
02In NFPA 70E 120.1 (2) [For Up To Date SLD]
03 NFPA 70E 120.2 B (3)Plan– [Planning for maintenance, re innovation or servicing]
04 In NFPA 70E 120.2(E) (5) for Interlock
05 In NFPA 70E 205.2
06 In NFPA 70E 340.7 (A.6) Up to date SLD to employee