What information can an SLD communicate?
An SLD communicates the primary power path and the identifiers needed to connect it to schedules, schematics and layouts.
| SLD item | Shows | Related detail |
|---|---|---|
| Bus | Connection and section arrangement | Equipment schedule |
| Breaker | Tag, rating and protection reference | Protection schematic |
| Transformer | Tag and supplied ratings | Data sheet and GA |
| Feeder | Destination and circuit identity | Cable schedule |
Which symbol source is relevant?
IEC 60617 is the official IEC source for graphical symbols used in electrotechnical diagrams. Projects may prescribe other approved libraries, so use the drawing standard supplied for the job.
Sources: International Electrotechnical Commission: IEC 60617 Graphical Symbols for Diagrams
Common questions
What else should the bid team know?
Does an SLD show physical equipment positions?
Usually not. General arrangements and layouts show physical position.
Does it contain protection settings?
It may reference protection devices, but detailed settings and coordination belong in approved studies and schedules.
Can a drafter create missing ratings?
No. Missing engineering inputs should be raised to the responsible engineer.
Primary sources
- IEEE C2-2023 National Electrical Safety CodeIEEE Standards Association
- IEC 61936-1:2021International Electrotechnical Commission
- IEC 60617 Graphical Symbols for DiagramsInternational Electrotechnical Commission
- 29 CFR 1910.269Occupational Safety and Health Administration