You are here: Home > Support > Knowledge Base > Light Fixture Cutoffs and Shields

Light Fixture Cutoffs and Shields

Thursday, August 29th, 2019

Q: Can Design Master Electrical and Design Master Photometrics account for different cutoff configurations on light fixtures?

A: Design Master does not account for cutoffs specifically; however, you can model an approximation using the Insert Solid commands.

NOTE: Some manufacturers may provide IES files for different cutoff configurations. Check for this first, as the IES files they provide will be more accurate than trying to model the cutoff yourself.

  1. Create the light fixture and insert it on the drawing.
  2. Run the Insert Solid: Line command.
    • Ribbon: DM Electrical->Point-by-Point Photometrics-> dm_elec-photoline Insert Photometric Solid: Line
      DM Photometrics->Solids-> dm_photo-photoline Line
    • Pulldown Menu: DM Electrical->Point-by-Point Photometrics->Insert Photometric Solid: Line
      DM Photometrics->Insert Solid: Line
  3. Set the Starting Elevation to an elevation below the fixture elevation. How far below will depend upon the type of cutoff you want to model (see image below).
  4. Set the Ending Elevation equal to the elevation of the fixture.
    Note: Setting this elevation higher will not affect light distribution for this fixture, but could affect light distribution for nearby taller fixtures.
  5. Press the OK button.
  6. Draw an approximation of the cutoff shape around the fixture (circle/semicircle for circular fixtures, rectangle/straight lines for rectangular fixtures, etc.).

Once the cutoff is drawn, perform a photometric calculation on the area to see if the light distribution is behaving the way you want. If the light distribution is too open or closed, use the dm_photo-query Querydm_elec-photo-queryLOO Query Calculation Area or Solid command to adjust the solid’s Starting Elevation, then recalculate. When the light distribution looks correct, you can then use the standard COPY command to place more fixtures with the cutoff on the drawing.


Related Articles

Filter by
Post Page
Electrical Light Fixtures Training Recording Electrical Training HVAC Diffusers
Sort by

Exempt Callout on Light Fixtures

Light fixtures marked as exempt are inserted on the drawing with an additional callout, which you may not want to display.


Incorrect Light Distribution from Light Fixtures

Odd light distributions can be caused by differences between the light fixture block and the IES file.


Training Recording: Light Fixture, Receptacle, Equipment, and Switch Options

This training video teaches you how to customize light fixtures, receptacles, equipment connections, and switches using the Design Master Electrical Options menu.


Exporting Light Fixtures or Diffusers for Reflected Ceiling Plan

Using the Copy Drawing and Remove Links to Database command, you can create a copy of the drawing that allows you to delete unnecessary entities without affecting the project.


Indoor Lighting Coefficient of Utilization

The CU is calculated using the IES file attached to the light fixture if possible; otherwise, a default value of 0.7 is used.



Electrical for Revit

Electrical for AutoCAD

HVAC for AutoCAD

Photometrics for AutoCAD

System Requirements


Contact Support

Install & Update Instructions

Online Training

Knowledge Base

User Manuals


Release Notes


Wish List

Remote Support



Customer Stories





Electrical for Revit

Electrical for AutoCAD

HVAC for AutoCAD

Photometrics for AutoCAD

Free Trial

Electrical for Revit

Electrical for AutoCAD

HVAC for AutoCAD

Photometrics for AutoCAD

8000 Regency Parkway, Suite 585
Cary, NC 27518
[email protected]

©2001-2023, Design Master Software, Inc