IEC, IEEE, ANSI and JIC: what the drawing references mean
Understand the different reference systems without assuming every similarly named library uses the same graphic or code.
Identify the system being referenced
IEC 60617 is a reference for graphical symbols used in diagrams. IEEE/ANSI 315 is a graphical-symbol and designation-letter reference with a historical lineage. IEEE currently lists the 1975 edition as Inactive-Reserved. ANSI/IEEE device-function numbers are a separate subject addressed by C37.2.
A drawing can contain a symbol, an equipment tag, a numbered protection function and a CAD block name together. These are different identifiers. Their presence does not establish a universal one-to-one conversion between standards or software libraries.
CAD library names are vendor identifiers
A public CAD reference might list horizontal and vertical block names for one device category. Those names are useful when identifying the software asset or searching documentation, but they are not necessarily official IEC graphical-symbol identifiers.
For example, Autodesk publishes named contact, transformer and circuit-breaker categories. Follow the relevant library documentation for its own conventions and software behaviour. Do not infer a connection contract or compatibility solely from a name.
Compare meaning as well as appearance
When comparing two depictions, consider the represented function, normal state, qualifiers and connection points. A different orientation may retain the same concept, while a small qualifier or contact-state change may change the meaning.
Useful comparisons distinguish equivalent concepts from approximate or application-dependent relationships. If an exact standards correspondence is not established, keep that limitation visible instead of labelling a similar-looking illustration as an official equivalent.
Use the specified convention for the deliverable
For an engineering drawing, use the applicable project requirements, standard and approved legend. Historical and vendor conventions remain relevant when reading existing drawings, but should be labelled with their source and edition.
The original illustrations in this library explain concepts. They are not reproduced standard graphics or a certified conversion library. The linked publisher references are the next step when an exact graphic or formal designation is required.
Graphical conventions and standards status
IEEE/ANSI 315 and its 315A supplement concern graphical symbols. IEEE lists these publications as Inactive-Reserved; identify the edition and convention required by the project rather than assume a legacy reference is a current project requirement. Device-function identifiers such as 50, 51 and 87 belong to IEEE C37.2 and do not replace the graphical symbol.
The convention collections identify specific forms from cited public vendor references. A comparable IEC or ANSI/IEEE representation can be linked where the evidence supports the same function. Differences in graphic form, qualifiers, terminal conventions and application still need to be checked. Vendor CAD identifiers are searchable aliases, not automatically standard symbol identity numbers.
Related references
Public sources
IEC 60617 and related symbol-design publications. Full database access requires a subscription.
Graphic symbols and designation letters. IEEE lists this edition as Inactive-Reserved; it is a historical reference, not a claim of current compliance.
Device function numbers, acronyms and contact designations. The full publication may require access through IEEE.
Public reference directory of named symbol categories. Vendor graphics and CAD library files are not redistributed here.
Distinguishes engineering use from reproduction of IEC publications and substantial database replication.
Independently authored educational guidance. Original diagrams; no customer drawings or arrangements. Last editorial update: 14 October 2026.