{"schemaVersion":1,"slug":"iec-junction-box-plan-mark","name":"Junction box plan mark","kind":"symbol","abbreviation":"JB","aliases":["joint box","connection box plan symbol","outlet box"],"category":"installation-communications","drawingTypes":["GA"],"referenceFamilies":["IEC"],"summary":"Plan mark for a junction or joint box where installation cables are connected or branched.","description":["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."],"readingNotes":["Check access to the box above fixed ceilings.","Look for the equipment it serves."],"drawingChecklist":["Confirm accessibility.","State enclosure rating.","Tag circuits passing through."],"distinction":"A conductor junction dot on a schematic shows electrical connection; this plan mark shows a physical box.","facts":[{"label":"Typical location","value":"Ceiling voids, plant areas, equipment connections"},{"label":"Access","value":"Must normally remain accessible"},{"label":"Exact standard graphic","value":"Not reproduced here; confirm the form against IEC 60617 and the project legend"}],"references":[{"sourceId":"iec-diagrams","relevance":"IEC graphical symbol context; independently drawn here."}],"related":["iec-conductor-connection-junction","iec-flex-outlet-plate"],"artwork":"s28-iec-junction-box-plan-mark","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Junction box, installation plan","reference":"IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier."},"plainEnglish":{"title":"What does Junction box plan mark mean?","introduction":"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.","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.","drawings":"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.","terms":[{"name":"Terminal","meaning":"An identified point where a conductor connects."},{"name":"Schematic","meaning":"A drawing showing function and connections rather than physical appearance."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"IEC graphical symbols for diagrams","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/"}],"detail":"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.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-junction-box-plan-mark","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-junction-box-plan-mark.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"iec-diagrams","title":"IEC graphical symbols for diagrams","publisher":"IEC","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/","type":"standard","scope":"IEC 60617 and related symbol-design publications. Full database access requires a subscription.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"IEC graphical symbol context; independently drawn here."}]}