JUNCTION
Conductor connection junction
A junction indication marks a documented electrical connection between conductor branches.
Schematic
IEC · JB
Junction box plan mark
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.
- Terminal
- An identified point where a conductor connects.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: IEC graphical symbols for diagrams
IEC · Junction box, installation plan
IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
GA · JB
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.
A distinction that matters
A conductor junction dot on a schematic shows electrical connection; this plan mark shows a physical box.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
IEC graphical symbols for diagrams
IEC graphical symbol context; independently drawn here.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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