What should the trace start with?
Start with the approved protection and control philosophy, device schedule and equipment interface. Then trace trip, close, indication, alarm, interlock and test points through the schematic.
| Path | Check | Evidence |
|---|---|---|
| Trip | Source, relay and breaker | Approved logic |
| Close | Permissive and interlock | Control philosophy |
| Indication | Status and alarm point | I/O schedule |
| Terminal | External interface | Terminal plan |
| Test | Access and record | Test procedure |
Sources: International Electrotechnical Commission: IEC 60617 Graphical Symbols for Diagrams
Which errors need an engineering question?
Raise any missing setting, conflicting device tag, unexplained interlock or unassigned interface. Do not infer whether a contact is normally open, normally closed or fail-safe without an approved basis.
Sources: IEEE Standards Association: IEEE C2-2023 National Electrical Safety Code, Occupational Safety and Health Administration: 29 CFR 1910.269
What does the drafter deliver?
The deliverable is a controlled schematic set with revision notes, source references and open-item status. It is not a protection study or engineering certification.
Common questions
What else should the bid team know?
Does drafting decide the substation design?
No. Drafting turns approved engineering inputs into controlled drawings. The responsible registered engineer makes design decisions and performs sign-off.
Can a drawing set use any symbol library?
Use the project drawing standard and approved symbol convention. Where a standard is specified, the project team confirms the applicable edition and licensed access.
What happens when a dimension is missing?
Show it as an open input or request the approved source. Do not invent a clearance, rating or equipment outline.
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