Finding one terminal in a large panel means first finding the right page, then the right circuit, then the right line. IEC 81346's multilevel designation is the path you walk in that search: the address is a standard answer to the question "where am I?".
In this article we explain what IEC 81346 labels mean and how EupCAD applies them while drawing — when you change a tag, the address, the terminals and the reports update together.
What is IEC 81346?
IEC 81346 (formerly IEC 61346) defines the rules for multilevel designation and addressing of technical systems. The goal is to produce an address for every component that is unique and meaningful to the reader. The address tells you the position in the hierarchy:
- Plant/area: which facility does the system belong to? (e.g. a production area, a pump zone)
- Document/section: which panel, which control section?
- Device: the specific device inside the section.
A short example: a contactor in "Control Panel A" of the "Pump Zone 1" of a plant. Read within the hierarchy, the address itself tells you where the device sits.
How is it different from "one letter + number"?
In older panels you may still see local labels like "K1, K2, K3". That works for a small panel, but as the number of panels grows, the same label is used for different devices in different panels. An IEC 81346 address is unique across the whole system: when you see the label, you know which plant, which zone, which device it is.
The difference is here: a local label binds the device to the panel; a multilevel address binds it to the plant.
In EupCAD the tag is classification data
In EupCAD a device's label (tag) is not just a name; it is the device's classification data. The moment you place a device, automatic addressing kicks in: the tag is formatted according to IEC 81346 rules and the device's terminals are labeled from that address.
The practical consequence is that changing the label happens in one place. When you update the device's tag:
- the device's own address is updated,
- the labels on its terminals are regenerated for the new address,
- reports such as the terminal schedule and cable list stay consistent.
In other words, instead of fixing addresses terminal by terminal, you change the source — the device definition — once.
The library comes with labeling
The 802 IEC symbols in the built-in library come with labeling built in: when you place a contactor, relay or fuse on the page, addressing is ready next to the symbol. When you import your own symbol, you apply the same addressing rules.
Why does this matter?
For three concrete reasons:
- Readability: the field team finds the device by reading the address — not by asking "which one is it?".
- Consistency: the address changes with the device, so there is no drift from hand-written labels.
- Report quality: the terminal schedule and BOM are produced from the correct address; material orders and field installation start from clean data.
Next step
In the demo project (ZONE1_PUMPS), browse the pages: compare the labels on the terminals with the rows in the terminal schedule report. You will see how the hierarchy is encoded in the address.