Diagram Symbols Used on LMXFORGE
LAST UPDATED: OCTOBER 2026 (REV. 1)
The figures in our articles use one set of electrical symbols, drawn to the forms in IEC 60617, the international graphical symbol standard. The same symbols are used whether the text is discussing NEC or IEC practice, so a figure reads the same way for every reader.
The NEC (NFPA 70) does not define drawing symbols. In the United States, power drawings usually follow IEEE 315 / ANSI Y32.2, which has been inactive since 2019 with no replacement. For the devices below, that convention uses the same transformer circles, fuse rectangle, earth symbol and machine circles.
Symbols
| SYMBOL | DEVICE AND IEC 60617 DESCRIPTION | HOW WE USE IT |
|---|---|---|
| Conductor, three-phase groupConnection; conductor; cable; line. Group of connections, number indicated (form 1: one slash per conductor). | Power conductors on one-line figures are plain lines. Three slashes mark a three-phase group. | |
| Transformer, two windingsTransformer with two windings, general symbol (form 1, IEC 60617 S00841). Form 2, the coil-loop version (S00842), is not used on this site. | Primary lead on the top circle, secondary lead on the bottom circle. No winding connection marks are drawn. | |
| Circuit breakerCircuit breaker: switch blade with the circuit breaker function mark (a cross) on the contact. | Shown open for clarity. Breaker and switch symbols vary the most between drafting practices, so check your own standard. | |
| Disconnector (isolator)Disconnector, isolator: switch blade with the disconnector function mark (a bar) on the contact. | No load-break or fault-break rating is implied by the symbol. | |
| FuseFuse, general symbol. | The line runs through the rectangle. | |
| BusbarDrawn as a heavy line. This convention is used on LMXFORGE figures; busbar is not listed in the reference sheet we checked. | Leads attach to the bus from above and below. | |
| Earth, groundEarth, general symbol. Ground (US), general symbol. | The same symbol is used on NEC and IEC figures. | |
| GeneratorMachine, general symbol, with the letter G replacing the asterisk: generator, synchronous generator. | ||
| MotorMachine, general symbol, with the letter M replacing the asterisk: motor, synchronous motor. |
Drawing rules
- One symbol per device. Where IEC 60617 gives two forms, we use form 1 everywhere and do not mix forms in one figure.
- Power flows top to bottom, from source to load. Leads leave the top and bottom of each symbol.
- Colour. Equipment symbols are amber, conductors are grey and busbars are heavy white lines on the dark theme. Print view switches to black and dark amber.
- No winding connection marks (delta, wye, grounding) on equipment symbols. Connections are given in the text and captions.
- Labels carry ratings (for example, 1,500 kVA). Symbols carry no values.
Authority
These drawings are our own renderings of the IEC 60617 forms and are for explanation only. The standard itself is the authority: see the IEC graphical symbols database for the official symbol. Your project or client drafting standard governs the drawings you issue.