The corridor on a typical floor is under two metres wide and the ceiling void is already full of ductwork and pipes. A 300 mm ladder tray has to fit in there, turn into the service shaft and carry on to the floor above. Draw that in 2D and every change of elevation means redrawing a section, with nobody quite sure whether the tray clears the beams.
A Revit cable tray is a three-dimensional element with a width, a height, an elevation and fittings that appear on their own when the run turns. You start it at Systems › Electrical › Cable Tray (shortcut CT); conduit sits next to it under Conduit (CN). This article walks through thirteen steps in Revit 2027: declaring sizes in Electrical Settings, picking a type with or without fittings, drawing the run, going up a floor with the Create Riser button, connecting conduit and tagging the result. For the electrical model end to end, the Institute runs a Revit MEP course.
What Revit means by cable tray and conduit
Ladder tray, covered trunking, plain trunking and wire basket all belong to one category: Cable Trays. Conduit is a separate category, Conduits. Both are system families, which means they live inside the project file rather than being loaded like equipment families; a new type is a duplicate of an existing one in Type Properties.
Each category then splits in two, and choosing the wrong half is the mistake that shows up later in the quantities.
| with Fittings | without Fittings | |
|---|---|---|
| At a change of direction Revit places | a separate fitting: bend, tee, cross | a bend counted as part of the run |
| Suits | ladder and trunking assembled from pieces, conduit with elbows and boxes | conduit bent on site, trunking bent from one sheet |
| Schedules as | Cable Trays plus Cable Tray Fittings | Cable Tray Runs: the length of the whole run, bends included |
On a plan the graphics follow the detail level of the view: at Fine the rungs of a ladder tray are drawn, and at lower detail levels the tray collapses to simpler linework. Conduit is a single line at the lower levels.
The file used here
The screenshots come from a copy of the Institute's electrical sample file linked to the Snowdon Towers architectural model that ships in the Samples folder of Revit. How to get both files and link them is covered in Revit MEP sample files.
You need three things before drawing: a floor plan that shows the architectural walls, a level above for the tray to rise to, and the Properties palette open. What the software covers for building services is set out in what Revit MEP is. Nothing else, because tray and conduit do not belong to a logical system the way pipes and ducts do.
Steps 1–3: declare tray and conduit sizes in Electrical Settings
Tray widths cannot be typed freely. Revit only offers sizes that exist in a table, so the table comes first.
- Go to Manage › Settings › MEP Settings › Electrical Settings, or type ES.
- Open the Cable Tray Settings › Size branch. The Size column is the width; the Used in Size Lists column decides whether that size appears while you draw. New Size… adds one, Modify Size… edits one.
- Open Conduit Settings › Size. Conduit is grouped by Standard, each standard holding its own table of trade sizes with inside diameter, outside diameter and minimum bend radius. The two small buttons beside the Standard box add or delete a standard.
The Rise Drop branches just above set the rise and drop symbols — the circle or tick you see on plan where a run changes elevation. You pick from the symbols supplied; you cannot draw your own.
Steps 4–6: pick a tray type and set the size
- Open the floor plan and click Systems › Electrical › Cable Tray (CT). The ribbon changes to the Modify | Place Cable Tray tab.
- Open the Type Selector at the top of the Properties palette and pick a type. The sample file holds ladder and trunking types under Cable Tray with Fittings, plus Channel and Ladder under Cable Tray without Fittings.
Click Edit Type to see which cable tray fittings the type is using. The seven rows in the Fittings group are the seven situations Revit has to resolve for you; leave one empty and the run stops working the moment it meets that situation.
- Set the size and elevation on the Properties palette: Width and Height under Dimensions, Middle Elevation under Constraints for the centreline height above the level. In the 2027 release there is no width or height box on an options bar; the numbers live in Properties, while the ribbon keeps Offset and Bend Radius.
Steps 7–9: draw the run and change floors
- Click the first point in the corridor and move the cursor. A temporary dimension appears, so you can type the length instead of aiming. The second click ends the first segment and the command carries on from there.
- Click a point off the current line and the run turns, with a bend inserted for you. Its radius comes from the Bend Radius box on the ribbon and its family from the Horizontal Bend row of the type.
- To take the run up or down, type the new height into Middle Elevation while the command is still running, then click Create Riser on the Placement Tools panel. Revit builds the vertical piece between the two elevations and adds the two vertical bends. That button is new in the 2027 release and works the same way for duct, pipe, tray and conduit.
That vertical piece is what the drawings call a cable tray riser. Check it in a 3D view: it has to sit inside the shaft, and the two vertical bends have to be the families you assigned in Type Properties.
Steps 10–13: revit conduit, parallel conduits and tags
Getting from the tray down to a board or a device is conduit work. The moves are the same as for tray; only the size box differs.
- Click Systems › Electrical › Conduit (CN). Pick a type in the Type Selector, then set Diameter(Trade Size) and Middle Elevation in Properties.
- Start the run on the edge of a tray and the conduit connects to it. The conduit may sit above, below or level with the tray.
- With one run in place, a whole bank of them comes from Systems › Electrical › Parallel Conduits. On the ribbon choose Same Bend Radius or Concentric Bend Radius, then set Horizontal Number, Vertical Number and the offsets. Hover over the original run, press Tab to catch the whole run, and click.
According to the Autodesk page Draw Parallel Conduits, the command only accepts a run connected through a surface connector on equipment or connected to a cable tray, and the concentric option is for conduit without fittings.
- Put the sizes on the drawing: leave Tag on Placement on while you draw, or tag afterwards with Annotate › Tag by Category. If the file holds no tag family for that category Revit answers No Tag Loaded; load one from Annotate › Tag › Loaded Tags and Symbols and tag again. Tagging in general is covered in tags in Revit.
What the ribbon options do
| Button or box | What it does |
|---|---|
| Create Riser | Adds a vertical piece from the current height to the height you just typed in Properties |
| Automatically Connect | Connects to a component's connector when you snap to it; switch it off when two runs share a path at different heights |
| Inherit Elevation, Inherit Size | Take the height or the size from the element you snap to |
| Offset, Bend Radius | The offset of the run from the line you click, and the bend radius of the fittings |
| Add Vertical, Change Slope (conduit) | Join two heights with a vertical piece, or with a sloped one |
| Tag on Placement | Tags as you draw, with boxes for orientation and leader |
The Justification settings in Properties decide which part of the section follows the line you draw: Horizontal Justification (Center, Left, Right) and Vertical Justification (Middle, Top, Bottom). For a tray tight under the slab, set Vertical Justification to Top and give the soffit height; no arithmetic needed.
Coming from CAD
People used to 2D drawings look for a tray library, meaning blocks of two lines with a size written beside them. Revit has no equivalent and needs none. The tray itself carries the size and the height: the linework on plan is drawn by Revit at the detail level of the view, and the size text comes from a tag.
| On CAD | In Revit |
|---|---|
| Insert a tray block at the right scale | Pick the type, type Width and Height |
| Draw two lines and letter the size | Draw one run, place a tag that reads the size |
| Draw the rise and drop symbol by hand | The Rise Drop symbol from Electrical Settings appears on its own |
| Count bends and tees for the quantities | A Cable Tray Fittings schedule counts them |
Old CAD sheets are still useful: link the DWG as a background, draw over it, and switch its layers off as each run is finished. Managing backgrounds and linked models is covered in linking Revit models.
When it will not work
| What you see | Why | What to do |
|---|---|---|
| The size you need is not in the list | The size is missing, or Used in Size Lists is cleared | Electrical Settings › Size: add it or tick it again |
| The run does not appear on plan | Its height falls outside the View Range of the view | Change the View Range, or lower the run |
| The tray is one line, no width | The view is at Coarse detail level | Switch Detail Level to Medium or Fine |
| Two runs touch but do not connect | Different heights, or Automatically Connect is off | Put both at the same height, switch the option back on |
| A turn reports that no fitting can be placed | The type has no family for that situation | Edit Type and fill the empty row in the Fittings group |
| Parallel Conduits will not catch the run | The original run is connected to neither tray nor equipment | Connect its end to the tray or to a surface connector, then repeat |
| Tagging answers No Tag Loaded | The file has no tag family for that category | Annotate › Tag › Loaded Tags and Symbols, load a tag family and tag again |
Three things worth unlearning
| Often heard | What the 2027 release actually does |
|---|---|
| You need to download a tray family first | Tray and conduit are system families already in the file; only fitting families are loaded |
| A type without fittings needs no fitting families | It still needs all of them; the difference is that the bend length counts as part of the run |
| Going up a floor means drawing in a section | Type the new height and click Create Riser on the plan |
Frequently asked questions
Can I type any tray width I like?
No. Revit only offers widths that exist in Electrical Settings › Cable Tray Settings › Size and are ticked in Used in Size Lists.
With fittings or without?
Ladder and trunking assembled from pieces: with fittings, so bends and tees can be counted. Conduit bent on site: without fittings, and then the length of the whole run is the number you take off.
Can conduit connect to a tray?
Yes. Start the conduit on the edge of the tray; it may run above, below or level with it.
Where does the default bend radius come from?
From the tray width multiplied by the Bend Radius Multiplier in Type Properties. The Bend Radius box on the ribbon overrides it for the run you are drawing.
Can a Revit cable tray be scheduled?
Yes, through the Cable Trays, Cable Tray Fittings or Cable Tray Runs categories. Building schedules is covered in schedules in Revit.