CMC selector switches have hundreds of thousands of possible combinations, all with their own unique part number. This page will walk you through how to find the part number of the unit you’re looking for. An example of a finished part number is 913AEA011. The part number can be split into 913-A-E-A-01-1. The “913” is the operator knob color, the “A” is the selector action, the “E” is the cam code, the second “A” is the operator function, the “01” is the number of lamp terminals and types of lamps, and the “1” is the cam orientation.

Step 1: Determine Knob Color

If grey, the part number starts with 910

If black, the part number starts with 913

Step 2: Determine Selector Action

Identify the letter that matches up with positions needed and put that onto the part number.

Step 3: Determine Cam Code

Match your circuit requirements in one cam code column from the chart.

Develop the catalog listing of the unit, including the shaded area letters of the cam code configuration selected.

Consider position number 1 as the furthest counter-clockwise device position. Order contact block(s) and adapter kit as indicated in the left hand column of the cam code selection chart.

Step 4: Determine Operator Function

The letter representing the operator function will be A, B, C, D, or F.

A – Maintained

B- Clockwise spring return from left (2 and 3 position)

C- Counterclockwise spring return from right (2 and 3 position)

D- Clockwise and counterclockwise spring return to center from left and right (3 position)

F- Uni-rotational clockwise (4 position only, no stop)

Step 5: Determine Lamp Terminals and Service

Identify the numbers that match up with the number of terminals and type of lamp needed, and put that into the part number.

Step 6: Determine Cam Orientation

Insert the cam orientation code from the shaded area of the cam code chart. The area is labeled orientation and it must be from the same column as the cam.


Once you get through all 6 steps, you’ll have a complete part number. If you need a quote on your switch, or have a more complicated switch that doesn’t match up with any of our standard circuit configurations, be sure to contact us.


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