wires_per_terminal

Wires per terminal: limits and chains

A real terminal takes one or two wires — four at most, with a double ferrule either side of the screw. A folio report (the arrow that carries a wire to another sheet) is not a terminal at all: it is a virtual point, and the clearest drawing gives it exactly one wire. QElectroTech has never checked either: any number of wires can be connected anywhere, and a drawing that looks fine can be impossible to wire in the workshop.

This page covers a set of optional rules that make QElectroTech check this while you draw and list the places where an existing drawing breaks it. They were asked for in discussion #1158.

Everything here is off until you turn it on. A project that never uses these rules is drawn and saved exactly as before, and one switch in the preferences turns all of them off for every project.

It is experimental. The rules count the wires on a terminal as QElectroTech represents them today. If wires and conductors become separate objects in a future version, these rules — and the values you set — may have to change. QElectroTech says so in a warning pop-up when you turn a rule on (a limit where there was none, or one wire per folio report).

§	Feature	Where	Pull request
1	The limits, set for every project, and the master switch	Configure QElectroTech › General	#1272
2	A project's own limits	Project properties	#1272
3	What is refused, and what is not	while drawing	#1272
4	Chains instead of stars	polygon wiring, deleting a symbol	#1273
5	Counting with an AI assistant	qet_check	#1271

Menu and option names are given in French, as QElectroTech shows them until the translations are updated, with an English gloss in italics.

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1. The limits, set for every project

Settings → Configure QElectroTech, page General, tab Appearance:

Option	Default	What it does
Apply the projects' conductors-per-terminal rules — the master switch	ticked	unticked, every rule on this page is off in every project, whatever the project says. The other options grey out
Maximum conductors per terminal	No limit	a new wire that would give a terminal more than this is refused. 4 is two double ferrules, one either side of the screw
Only one conductor per sheet reference	unticked	a folio report takes one wire, whatever the limit above

These values are kept with your other QElectroTech settings, on this computer, and apply to every project that does not set its own (§2). Changing them takes effect at once, in projects already open too.

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2. A project's own limits

Project → Project properties, page General, the Conductors per terminal group:

• Use the application settings is ticked by default. The fields below then show the values from §1, greyed: that is what this project follows.
• Untick it to give this project its own values. They start from the application's, become editable, and are saved in the project file, so the project keeps them on any computer — useful when a drawing must follow a customer's rule whatever the preferences of whoever opens it.
• A project's own No limit beats an application limit: tick the box off and set no limit for, say, a single-line diagram where one drawn wire stands for several.
• With the master switch (§1) off, the whole group greys out with a note, and nothing in it applies.

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3. What is refused, and what is not

Refused: drawing a new wire onto a terminal that already has as many wires as the limit — or, with the report rule on, a second wire onto a folio report. While you drag, the terminal shows in red, as for any connection QElectroTech refuses. When you let go, nothing is drawn and a tooltip says why:

The limit applies to both ends: dragging from a full terminal is refused too.

Also respects the limit:

Action	What happens at a full terminal
Automatic conductor creation (placing or moving a symbol whose terminal lines up with another)	that wire is not created; the others are
Multi-paste with automatic connection	same
qet.addConductor() in a script	returns false and logs that the limit was reached

Never refused: wires that are already in the drawing. Opening a project, pasting, undo and redo, and dropping a symbol onto a wire to split it all work as before, even where a terminal is over the limit. QElectroTech has no list of those terminals; the AI assistant check in §5 finds the ones with more than four wires.

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4. Chains instead of stars

Two of QElectroTech's own tools connect several terminals at once, and both used to connect them all to one of them — a star:

• drawing a polygon around terminals to wire them together (also qet.addConductor() in a script);
• deleting a symbol that sat on a potential: QElectroTech rewires the terminals it was connected to, so the potential is not broken.

Six terminals wired as a star give the middle one five wires, which no limit allows. When a wire limit is set, both tools now wire the terminals one after another: starting from the top-left terminal, each time to the nearest one not yet wired. Every terminal in the middle of the chain gets two new wires, the two ends one each, and the result reads as a wiring order. The polygon tool also leaves out a wire whose terminal is already full.

Without a limit (or with only the report rule), both tools build the star as before.

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5. Counting with an AI assistant

The qet_check tool of the AI assistant server gets two read-only checks, so you can count a project before turning any limit on:

Check	Reports	Severity
crowded_terminals	terminals with more than four wires, folio reports left out, with folio, cell, label, symbol type and wire count	info
reports_with_several_wires	folio report arrows with more than one wire	info

Both are information, not errors: cable, busbar and single-line symbols carry more wires on purpose, and a third of the shipped examples' folio reports have several. Over the 24 example projects they find 23 crowded terminals in 10 projects and 130 reports in 4.

They are plain queries on the wires, so they work on any current QElectroTech, with or without the features above.

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6. In the file

Where	What is stored	When
your QElectroTech settings, group diagrameditor	wiring_rules_enabled (master switch), wiring_rules_max_wires, wiring_rules_one_wire_per_report	always, on this computer only
the project, <wiring_rules …/> under <project>	the project's own values: max_wires_per_terminal="2", one_wire_per_report="true"	only when the project sets its own (§2); <wiring_rules/> alone means "its own: no rule"

A project that follows the application's settings writes nothing, so it is saved exactly as before. An older QElectroTech drops a project's <wiring_rules> element when it saves, which simply means "back to no rule".

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Limitations

• The rules count wires on a terminal. They do not know about ferrules, bridges inside a terminal strip, or how many conductors a real device's data sheet allows: the numbers are yours to set.
• A project opened on another computer follows that computer's preferences, unless the project has its own values (§2).
• Wires already in the drawing are never removed or moved, and QElectroTech itself has no list of the terminals that are over the limit; the crowded_terminals check (§5) lists those with more than four wires, the rest is up to you.
• The limit is one number for the whole project. A symbol cannot give one of its terminals a limit of its own (an earth terminal at 1, a cable or busbar symbol at no limit).

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See also

• Conductors — wire properties, the wiring list, and hops where wires cross
• Preferences reference — every settings page
• Using the element editor — terminals and their properties
• Terminal strips — where wires land on real terminals
• Linking wires across pages — folio reports
• The project database — the views a query can read
• AI assistants — the qet_check tool