To insert a low voltage device, go to
DM Electrical 
Low Voltage Devices Insert Low Voltage Device
The Insert Low Voltage Device dialog box will appear.
Select the low voltage device group (LVD group) from which you want to select a device, then click on the Callout of the device you want to insert.
Specify the Layer System on which to place the light fixture.
Press OK. Design Master will take you to the drawing.
Click to place the low voltage device on the drawing, then click again to indicate the orientation of the device.
You may either continue inserting low voltage devices of the same type, or press ENTER to finish the command.