KiCad ERC: Wires not connected to anything

Diagnostic signature

Wires not connected to anything

A KiCad Electrical Rules Check (ERC) diagnostic indicating that a schematic wire segment has an open end that does not terminate at a valid connection point, such as a component pin, label, power port, or another wire.

What it means

In the KiCad Schematic Editor (Eeschema), the Electrical Rules Check (ERC) evaluates whether a circuit drawing represents a logically and electrically complete netlist. The warning 'Wires not connected to anything' (internally identified as `wire_dangling`) means that a drawn wire segment possesses at least one terminal point that does not coincide with a valid electrical node. Valid nodes include component pins, hierarchical or global labels, power ports, or intersections with other wires. When a wire terminates in empty canvas space, the schematic cannot resolve what that node is supposed to connect to, risking an unintended open circuit on the final PCB.

Why it happens

This ERC violation is typically introduced through minor drafting inaccuracies. The designer may have stopped drawing a wire just short of a pin or label, missing the precise schematic grid coordinate required to form an electrical connection. It frequently happens when moving a component using the standard 'Move' command rather than the 'Drag' command, which severs attached wires and leaves the original endpoints floating. Additionally, deleting a symbol or a previously connected wire segment without also removing all intermediate routing stubs will leave remnant dangling wires on the canvas.

Minimal reproduction

(kicad_sch (version 20231120) (generator "eeschema")
  (uuid "00000000-0000-0000-0000-000000000000")
  (paper "A4")
  (wire (pts (xy 50.8 50.8) (xy 76.2 50.8))
    (stroke (width 0) (type default))
    (uuid "11111111-1111-1111-1111-111111111111")
  )
)

How to fix it

Remove the superfluous floating wire segment or extend it to terminate at a valid component pin or label.

```KiCad Schematic
(kicad_sch (version 20231120) (generator "eeschema")
  (uuid "00000000-0000-0000-0000-000000000000")
  (paper "A4")
  ;; The dangling wire segment has been removed to resolve the ERC violation.
)
```

Step 1

• Open the `.kicad_sch` file in the KiCad Schematic Editor.

Step 2

• Locate the specific wire flagged by the ERC warning arrow.

Step 3

• If the wire stub is unintended, select the wire segment and press 'Delete'.

Step 4

• If the wire was meant to complete a circuit, select its endpoint and drag it until it snaps precisely onto the intended component pin or label.

Step 5

• Re-run the Electrical Rules Checker to ensure the 'Wires not connected to anything' diagnostic is cleared.

Upstream references

Schematic Editor | 8.0 | English | Documentation

Issue #11164: Broken schematic after update to 6.0.3. 'Wires not connected to anything'

eeschema/erc/erc_item.cpp (KiCad Source Code)