# Busway tap-off connection

Canonical URL: https://eloragrid.ai/symbols/busway-tap-off-point
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: TO
Drawing use: SLD
Reference families: IEC, IEEE / ANSI, Manufacturer

The connection of an outgoing circuit to a plug-in busway through a tap-off unit, usually containing a protective device.

## In plain English

### What does Busway tap-off connection mean?

This symbol shows a tap-off unit plugged into the busway, with the outgoing circuit leaving through a fuse or circuit breaker in the unit. On single-line diagrams it replaces the board-and-feeder pattern used for switchboards, since the busway itself acts as the distribution bus.

### A simple example

The connection symbol does not show the tap-off unit rating unless annotated. Tap-off units may be fused or contain a breaker, and they usually have an interlock preventing insertion or removal under load. The protective device inside the unit should be drawn with its own symbol and rating.

### What the drawings help you do

Read the protective device rating in the tap-off unit. Check selectivity between the tap-off device and busway upstream protection. A busway tap-off is a plug-in connection with its own protection; a one-line bus tap is a generic connection to a busbar.

### This particular reference

The connection of an outgoing circuit to a plug-in busway through a tap-off unit, usually containing a protective device. A busway tap-off is a plug-in connection with its own protection; a one-line bus tap is a generic connection to a busbar.

### Terms

- Terminal: An identified point where a conductor connects.
- Rating: A value stating the conditions for which equipment is specified.
- 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.

- [Canalis busbar trunking systems](https://www.se.com/ww/en/work/products/master-ranges/line-series/)
- [Autodesk IEC-60617 preview: One-line bus-tap representation](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-9EC851F1-8B92-428B-A657-5B21B2325C62.htm)


## What it represents

This symbol shows a tap-off unit plugged into the busway, with the outgoing circuit leaving through a fuse or circuit breaker in the unit. On single-line diagrams it replaces the board-and-feeder pattern used for switchboards, since the busway itself acts as the distribution bus.
The connection symbol does not show the tap-off unit rating unless annotated. Tap-off units may be fused or contain a breaker, and they usually have an interlock preventing insertion or removal under load. The protective device inside the unit should be drawn with its own symbol and rating.

## How to read it

- Read the protective device rating in the tap-off unit.
- Check selectivity between the tap-off device and busway upstream protection.

## Information to show or reference

- Draw the protective device in the tap-off.
- State tap-off rating.
- Identify the busway outlet position.

## Important distinction

A busway tap-off is a plug-in connection with its own protection; a one-line bus tap is a generic connection to a busbar.

## Facts

- Graphic cue: Short branch from busway line into a protective device
- Physical item: Plug-in tap-off unit
- Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic

## Public references

- [Canalis busbar trunking systems](https://www.se.com/ww/en/work/products/master-ranges/line-series/) — Schneider Electric. Manufacturer busbar trunking ranges with tap-off units.
- [Autodesk IEC-60617 preview: One-line bus-tap representation](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-9EC851F1-8B92-428B-A657-5B21B2325C62.htm) — Autodesk. Public IEC-oriented one-line bus-tap representation for comparison.

## 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.