Nuclear Plant Control Room Switches and Components

Nuclear Plant Control Room, Courtesy NRC, CC BY 2.0

Some of these operator controls and indicators are hard to locate…


The General Electric ET-16 indicating lamp is a common indicating light used in nuclear power plant control rooms and control panels.

The ET-16 light comes in either incandescent or LED models. The LED models consume less power, but the general shape, size, panel cutouts, and mounting requirements are the same. The ET-16 has a large white resistor mounted to the back. The resistor value varies with the circuit voltage.

Red GE ET-16
GE ET-16 full body and resistor

A brochure on the incandescent model can be found by clicking here: GE ET-16 Incandescent Light.

A brochure on the LED model can be found by clicking here: GE ET-16 LED Light.

A second option is the Eldema R-series light. These are smaller than the GE ET-16. The rear-mounted RLE model is a good match for control room panels. These indicating lights are designed to use the midget flange based T-1-3/4 incandescent or LED lamps. Because they are smaller, you can fit more within a given area than the ET-16. They require resistors, too, but they are usually mounted in groups in the back or side of the panel.


There are a variety of control switches found in control rooms and in control panels located throughout the plant.

The GE CR104P is a common selector switch. They are classified within the pilot device line of components. They are heavy-duty switches. The description from the sales literature provides a generally accurate assessment:

“Those who actually use them appreciate the CR104P’s positive touch, crisp action and ease of operation. The push buttons feel solid. Selector switches offer easy-to-grip knobs and a positive snap. Every element demonstrates a rugged, heavy-duty nature and purpose. These things make a real difference in everyday use.”

The switches have modular contact blocks attached for accepting conductor terminations. Additional contact blocks can be added. In 2017, GE Industrial Solutions was acquired by ABB. The ordering catalog is available on ABB’s website.

There are different options and configurations available. For example, the switch can be keyed so that a key must first be inserted before it can be turned. Here is a short one-minute sales video that shows high-resolution close-up footage of assorted GE pilot devices:

An alternative line of switches used in control room panels may be supplied by Kraus & Naimer, a long-term manufacturer of rotary cam switches. These have been used as replacements for old obsolete GEMCO switches. They are similar to the GE switches but may offer more features. The CA10 switch is a general purpose switch. Low-current contacts are available for PLC applications.

You can watch a short 1-minute video showing how the switches work below, in an official K&N video:


These are unique components that some control rooms use. These definitely have a military feel, like something you might find in the cockpit of a NASA space shuttle:

Or, possibly, even like something you might find in an episode of The Good Place (Season 4, Episode 11–even Michael looks surprised that we caught him):

One brand is the Safran Series 10 Twist Lite. They are distributed by Flamecorp. Eaton sold two of its aerospace businesses to Safran in 2014, the Integrated Cockpit Solutions business and Aerospace Power Distributions Management Solutions. Prior to that, Eaton must have acquired Master Specialties Company (MSC), who made them originally.

You can download the old Eaton/MSC catalog here: Eaton/MSC Series 10 Twist Lite Catalog from circa 1991.

Another brand you may encounter is the Senasys, formerly Honeywell, CMC 908 indicators and 910 & 913 selectors. These are similar to the Series 10. These may be located more often in control panels outside the control room.


Because these components can sometimes be tricky to find, I’ve compiled some of them here, with links and pictures.