# Rule set (thresholds)

Source: https://meptools.com/tools/ceiling-coordination-studio/docs/rule-set/

Open **Rule Set** on the ribbon to see and adjust the numeric thresholds the compliance
checks use for this project.

![Rule Set panel showing the four thresholds with their preset values](./_assets/ccs-rule-set-panel.png)

## The four thresholds

| Threshold                    | Tool Default | Editable range |
| ---------------------------- | ------------ | -------------- |
| **Zone B minimum width**     | 600 mm       | 300–2000 mm    |
| **ELV / non-ELV separation** | 300 mm       | 0–1000 mm      |
| **Clearance above dry tray** | 250 mm       | 0–1000 mm      |
| **Arm's reach limit**        | 900 mm       | 400–2000 mm    |

A value you type outside the editable range is rejected and the preset value keeps being
used — it isn't silently clamped to the nearest bound.

## Where the numbers come from

Every threshold is classed as either a **Convention** or **Tool judgement** — none of them
is a code-mandated figure. The panel shows the reasoning behind each one (industry
rule-of-thumb, a related standard's figures, or the tool's own model) next to its value, so
you can judge whether it fits your project or needs overriding.

Only one preset — **Tool Default** — ships today.

## Overriding a value

Change a threshold and the panel marks it **Overridden**, with a table comparing the preset
value to the one in use. **Reset to preset** clears an override back to the preset value.
Overrides are saved with the project, so reopening it later re-checks the layout against the
same numbers you set.

## Why this matters for auto-arrange

**Auto arrange** (see [Auto arrange](/tools/ceiling-coordination-studio/docs/auto-arrange))
lays the section out against these same thresholds, so tightening or loosening a value here
changes how much room the automatic layout reserves before you run it.