A downloaded light fixture is usually just a solid. It looks right in the ceiling, but renders come out dark, the lighting circuit will not take it, and the schedule shows no load. The cause is almost always one of three: no light source, no IES file, no electrical connector.
Building lighting fixture families in Revit that do all three takes about half a day. This article walks through 15 steps in Revit 2027: pick a ceiling-based template, define the light source, attach an IES file, add the electrical connector and draw the plan symbol. To learn power and lighting on one sample building, see the Institute's Revit MEP course.
Generic family skills — reference planes, solids, parameters — are covered in how to create a family in Revit. This article covers the lighting-specific half.
What makes a light fixture family different
A light fixture is the only family type that carries an object which emits light. Autodesk defines it in one line on About the Light Source for a Lighting Family: "A light source is the part of a lighting fixture that emits light (such as a light bulb)".
That light source drives three things in the project.
| What the light source declares | What it affects |
|---|---|
| Emit shape and light distribution | how light renders, the wash on walls and floor |
| IES file | the real intensity distribution of the luminaire, used for illuminance |
| Luminous flux, colour temperature, loss factor | brightness and colour in rendered images |
None of that replaces the electrical connector: to circuit the fixture, feed a panel schedule and report load, the family still needs a connection point, like every MEP equipment family.
Choosing a lighting fixture template
The metric template folder shipped with Revit holds nine files for lights, split along two axes: the shape of the light source and the host.
| Template | Used for |
|---|---|
Metric Lighting Fixture.rft | free-standing fixtures: pendants, floor lamps, pole lights |
Metric Lighting Fixture ceiling based.rft | ceiling-hosted: recessed and surface mounted |
Metric Lighting Fixture wall based.rft | wall-hosted: wall washers, mirror lights, exit signs |
Metric Linear Lighting Fixture ... | battens and continuous runs |
Metric Spot Lighting Fixture ... | spotlights with a beam angle |
The choice is not reversible: a family built from a ceiling-based template will always demand a ceiling face in the project. This article builds a recessed downlight family from the ceiling-based template.
Steps 1–4: open the template, check the category, build the body
Step 1. Go to File › New › Family, switch to the English folder and pick Metric Lighting Fixture ceiling based.rft. The family opens in Reflected Ceiling Plan: Ref. Level — a ceiling plan, not a floor plan.
Step 2. On the Create tab, Properties panel, click Family Category and Parameters and check two things: the category is Lighting Fixtures and the Light Source parameter is ticked. Clear that box and the family loses its light source entirely.
Step 3. Build the body with Extrusion. For a recessed downlight, sketch a circle around the origin and push the solid above the ceiling plane: Extrusion End 100, Extrusion Start 0.
Step 4. Lock the body size to a parameter if you plan several sizes. A downlight usually needs only a diameter, so one Type parameter is enough.
Steps 5–8: light source definition — emit shape and distribution
Step 5. Select the light source by clicking the yellow circle at the origin. The ribbon switches to Modify | Light Source with a Lighting panel and a Light Source Definition button. The same button sits in Properties under Photometrics.
Step 6. Click it to open the Light Source Definition dialog. It offers two rows: four emit shapes (point, line, rectangle, circle) and four light distributions (spherical, hemispherical, spot, photometric web).
Step 7. Choose the circle shape for the emitting face and the photometric web distribution so the light follows an IES file. The note under the dialog spells out the consequence: "Light source definition defines available parameters in type properties".
Step 8. Click OK. The light source Properties now carry Emit from Circle Diameter, Tilt Angle and Photometric Web File. These are type parameters, so they appear greyed here and are edited in the type table.
Steps 9–11: photometric web file and intensity
Step 9. Load the family into an open project with Load into Project, then open its Type Properties. Autodesk's Specify an IES File for a Light Source allows this step in either place: in the family through Family Types, or in the project through Type Properties.
Step 10. In Type Properties, scroll to the Photometrics group, click the Photometric Web File cell, then the browse button. The Select File dialog opens in the IES folder of the installation and filters on the .IES extension.
Autodesk describes the file in one sentence: "An IES file is a text file that describes the intensity of a light source at points on a spherical grid". Every luminaire manufacturer publishes IES files; use the file of the fixture you actually specify and the illuminance numbers start to mean something.
Step 11. Still under Photometrics, set Initial Intensity and Initial Color. The intensity cell opens a dialog that accepts five inputs: wattage, efficacy, luminous flux, luminous intensity, or illuminance at a distance.
Steps 12–13: the electrical connector
Step 12. Back in the family, click Electrical Connector on the Create tab, choose the Work Plane placement and pick the Ref. Level plane. The exact position matters less than on piped equipment, because wiring in the project stops at the edge of the fixture.
Step 13. Select the new connector and change System Type from Power to Power - Balanced. Only then do Number of Poles, Load Classification, Voltage and Apparent Power appear. Set one pole, 220 V, the apparent power from the catalogue, and Load Classification to Lighting.
The Lighting load group is what separates lighting load from receptacle load on the panel schedule. Set it wrong and the schedule still runs, but with the wrong demand factor.
Steps 14–15: plan symbol and final checks
Step 14. Construction drawings show a symbol, not the modelled solid. In the family, open the Annotate tab, Detail panel, click Symbolic Line and draw the symbol in the ceiling plan. The contextual ribbon carries a Subcategory list for the linework and a Visibility Settings button for the detail levels it appears in.
Symbolic lines only show in views parallel to the plane they were drawn in, so a symbol drawn in the ceiling plan appears in plan and not in elevation. For a symbol that keeps its orientation when the fixture rotates, nest an annotation family and switch on Maintain Annotation Orientation.
Step 15. Check three things before handing the family over: the light source is still there, the IES file is attached, and the connector carries the right load group. The 3D view shows all three at once.
Build or download: a note on lighting libraries
Not every fixture deserves a custom family, and lighting fixture families in Revit are cheap to download but expensive to fix.
| Situation | What to do |
|---|---|
| Common fixture, only needs shape and a circuit | load it through Insert › Load Autodesk Family, then check the connector |
| Specified manufacturer, illuminance required | build the family and attach the manufacturer's IES file |
| Several sizes of one model | one family, several types, size driven by a parameter |
| Multi-lamp luminaire | nest a child fixture family for each light source |
Downloaded content is usually missing exactly two things: the electrical connector and the IES file. Check quickly by selecting a fixture in the project and opening Type Properties: no Photometric Web File row means the light source was never set to a photometric distribution.
When the fixture will not light or will not circuit
| Symptom | Cause | Fix |
|---|---|---|
| Renders come out dark | the Light Source parameter was cleared | tick it again in Family Category and Parameters |
| No Photometric Web File row | the distribution is not photometric web | open Light Source Definition and pick the fourth distribution |
| The fixture will not join a circuit | no electrical connector, or System Type still Power | switch to Power - Balanced and set the voltage |
| Lighting load lands in the wrong group | Load Classification is not Lighting | fix it on the connector and reload the family |
| The fixture will not host on a ceiling | it was built from a non-hosted template | rebuild from the ceiling-based template; it cannot be converted |
| The symbol disappears in plan | the linework is not parallel to the view, or the detail level is off | check Visibility Settings on the symbolic lines |
Three things you often hear
| What you hear | What Revit 2027 does |
|---|---|
| An IES file is all you need for illuminance | The IES file is half of it; the project still needs spaces and calculation settings |
| Every fixture should be modelled in detail | A correctly sized body with the right light source is enough; detail only bloats the file |
| One family means one light source | Autodesk's own guidance is to nest child families for multi-lamp luminaires |
Frequently asked questions
Where do IES files come from?
From the manufacturer's product page. Revit also ships a folder of sample IES files, but those are generic and should only stand in until the fixture is specified.
Where does the light source sit in the family?
The lighting templates include a reference plane for the light source, and the source is locked to it. Build from a Generic Model template instead and you have to add the plane and tick the Light Source parameter yourself.
Symbolic lines or a nested annotation for the plan symbol?
Symbolic lines are enough for a fixed symbol. Use a nested annotation when the symbol must keep its orientation as the fixture rotates, or scale with the view.
The fixture has a light source, so why is the schedule load empty?
Load in a schedule comes from the electrical connector, not from the light source. Set Apparent Power on the connector and the numbers appear.