# Junction box plan mark

Canonical URL: https://eloragrid.ai/symbols/iec-junction-box-plan-mark
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: JB
Drawing use: GA
Reference families: IEC

## Symbol convention

Convention: IEC
Form: Junction box, installation plan
IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier.

Plan mark for a junction or joint box where installation cables are connected or branched.

## In plain English

### What does Junction box plan mark mean?

A junction box mark shows where cables are joined in an enclosure, commonly in ceiling voids for lighting circuits or above ceilings for equipment connections. Plans draw a small circle or square with a dot, sometimes labelled JB, at the location.

### A simple example

Access matters: joints must remain accessible for inspection unless a maintenance-free method is used, so the plan should not place a junction box above a fixed plasterboard ceiling without an access panel. The symbol helps coordinate this with architectural trades.

### What the drawings help you do

The mark does not show the number of terminals or cables. A junction box serving fixed equipment may also be a final connection point; check the schedule.

### This particular reference

Plan mark for a junction or joint box where installation cables are connected or branched. A conductor junction dot on a schematic shows electrical connection; this plan mark shows a physical box.

### Terms

- Terminal: An identified point where a conductor connects.
- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/)


## What it represents

A junction box mark shows where cables are joined in an enclosure, commonly in ceiling voids for lighting circuits or above ceilings for equipment connections. Plans draw a small circle or square with a dot, sometimes labelled JB, at the location.
Access matters: joints must remain accessible for inspection unless a maintenance-free method is used, so the plan should not place a junction box above a fixed plasterboard ceiling without an access panel. The symbol helps coordinate this with architectural trades.
The mark does not show the number of terminals or cables. A junction box serving fixed equipment may also be a final connection point; check the schedule.

## How to read it

- Check access to the box above fixed ceilings.
- Look for the equipment it serves.

## Information to show or reference

- Confirm accessibility.
- State enclosure rating.
- Tag circuits passing through.

## Important distinction

A conductor junction dot on a schematic shows electrical connection; this plan mark shows a physical box.

## Facts

- Typical location: Ceiling voids, plant areas, equipment connections
- Access: Must normally remain accessible
- Exact standard graphic: Not reproduced here; confirm the form against IEC 60617 and the project legend

## Public references

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) — IEC. IEC graphical symbol context; independently drawn here.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.