How to Choose Pushbuttons and Pilot Lights for Industrial Controls

Last updated:August 3, 2026

Pushbuttons and pilot lights give operators a clear way to control equipment and understand its status. Selecting the right components can also make future maintenance and replacement easier.

The challenge is that many devices look similar while differing in size, voltage, contact arrangement, environmental rating and accessory compatibility. Before ordering, confirm what the device needs to do and how it fits into the existing control system.

What Is the Difference Between a Pushbutton and a Pilot Light?

A pushbutton allows an operator to send a command to a control system. Common functions include:

• Start
• Stop
• Reset
• Jog
• Alarm acknowledge
• Cycle start

A pilot light provides visual information about the condition of a machine or process. Common indications include:

• Power available
• Machine running
• Machine stopped
• Fault or alarm
• Manual or automatic mode
• Maintenance required

Some products combine an illuminated pushbutton with both control and indication functions.

Start With the Required Function

Determine what the device needs to accomplish before selecting a product.

Questions to answer include:

• Is it a pushbutton, selector switch or indicator?
• Should the operator be momentary or maintained?
• Does it need illumination?
• What legend or label is required?
• Will employees operate it while wearing gloves?
• Is it replacing an existing component?
• Is it part of a safety-related function?
• What environmental conditions will it face?

A momentary pushbutton returns to its normal position when released. This style is commonly used for functions such as start, stop, jog and reset.

A maintained operator remains in its selected position until it is manually changed. Maintained operation is commonly found on selector switches used for mode selection.

The machine drawings and existing control sequence should determine which type is appropriate. Do not replace a momentary device with a maintained device, or the reverse, based only on appearance.

Choose the Correct Mounting Size

Common operator sizes include 16 mm, 22 mm and 30 mm. The measurement generally refers to the mounting-hole diameter.

16 mm operators

These are often used where panel space is limited. Their smaller size may offer fewer accessory choices than larger product families.

22 mm operators

This is a common size for modern industrial control devices. Many manufacturers offer complete families of operators, contact blocks, light modules, legend plates and accessories in this size.

30 mm operators

These are commonly found on older equipment, heavy-duty control stations and applications where a larger operating surface is preferred.

None of these sizes is automatically best. Follow the existing plant standard or match the equipment being serviced.

When replacing a device, measure the mounting opening and confirm the manufacturer’s exact series. Do not order based on the diameter alone.

Confirm the Control Voltage

Illuminated pushbuttons and pilot lights are available for different control voltages, including 24 V DC, 24 V AC and 120 V AC.

Check:

• The electrical drawing
• The existing light module
• The equipment nameplate
• The manufacturer’s part number
• AC or DC requirements

A device with the wrong voltage rating may not operate correctly and could be damaged.

Do not assume that all low-voltage modules are interchangeable. A module marked for 24 V AC/DC may support both current types, while another may be designed only for AC or only for DC.

If the voltage cannot be confirmed, stop and have a qualified person identify the control circuit before ordering or replacing the component.

Stay Within One Compatible Product Family

A complete modular pushbutton may include:

• Operator head
• Mounting collar
• Contact blocks
• LED or lamp module
• Transformer or voltage module
• Legend plate
• Guard
• Protective cover
• Enclosure

Parts from different manufacturers or product families may look alike without being interchangeable.

Before ordering an individual component, verify:

• Manufacturer
• Product series
• Mounting size
• Contact-block compatibility
• Light-module compatibility
• Voltage
• Color
• Environmental rating
• Required accessories

For an existing installation, use the complete part number whenever possible. A clear photograph of the front, back and markings can also help the supply counter identify the correct replacement.

Check the Environment

The surrounding environment affects the operator and enclosure needed.

Consider whether the device will be exposed to:

• Indoor dust
• Outdoor weather
• Water spray or washdown
• Oil or coolant
• Corrosive chemicals
• Extreme temperatures
• Frequent cleaning
• Physical impact
• A hazardous classified location

Look for the manufacturer’s complete NEMA Type, IP rating and environmental specifications. The enclosure, operators, gaskets and cable entries must work together as an assembly.

A high enclosure rating does not help if the pushbutton, unused opening or cable fitting does not maintain that rating.

NEMA Type ratings and IEC IP ratings use different test systems. Do not assume they are exact equivalents.

Hazardous locations require equipment specifically identified for the location and hazard. A weather-resistant enclosure rating by itself is not enough.

Use Clear Colors and Legends

Colors can help operators recognize controls quickly, but color should not replace a clear label.

Follow the facility’s documented control standard, machine drawings and applicable manufacturer guidance. Avoid creating a new color system for one panel if the rest of the facility uses a different convention.

Use specific legends such as:

• Conveyor Start
• Pump 2 Stop
• Alarm Reset
• Manual
• Automatic
• Cooling Fan Running

Vague or missing labels create confusion during operation and maintenance.

If a facility does not have a documented color and labeling standard, that decision should be made by the responsible engineering or safety team.

Treat Emergency-Stop Components Separately

An emergency-stop operator is part of a safety function. The red pushbutton head is only one component of that system.

A complete emergency-stop function may involve:

• Compatible contact blocks
• Safety relays or safety controllers
• Output devices
• Reset logic
• Fault monitoring
• Machine stopping behavior
• Required testing and validation

Do not design or modify an emergency-stop function from a general product guide.

For a replacement, confirm the exact manufacturer, series, contact arrangement, approvals and system requirements. If the proposed change affects how the machine stops or restarts, involve the facility’s qualified machine-safety professional, engineer or equipment manufacturer.

An emergency-stop button is also not a substitute for the employer’s lockout/tagout procedure.

Replacement Versus New Installation

Replacing an existing device

Collect:

• Full manufacturer name
• Complete part number
• Product family
• Mounting size
• Voltage
• Contact arrangement
• Color
• Legend
• Environmental rating
• Photographs of the front and back
• Equipment drawings, when available

Avoid substituting a part unless compatibility and suitability have been confirmed.

Planning a new control station

Provide the supplier or project team with:

• Required functions
• Number of operators
• Control voltage
• Preferred product family
• Mounting size
• Environmental conditions
• Required legends
• Enclosure requirements
• Project drawings or specifications
• Required approvals

Safety-related functions should already be defined by the responsible engineer or machine-safety professional.

Common Ordering Mistakes

Ordering only the pushbutton head

Many modular devices require a separate mounting collar, contact blocks and other components.

Choosing the wrong voltage

Illuminated devices must match the actual control voltage and current type.

Mixing product families

Similar-looking contact blocks and light modules may not be compatible.

Forgetting the legend plate

A functioning button can still be confusing if its purpose is not clearly identified.

Ignoring environmental conditions

A general-purpose operator may not be suitable for outdoor, wet, dusty or corrosive locations.

Treating an emergency-stop head as a complete system

The operator alone does not establish the required safety function.

Trusting an incomplete part number

One missing letter or number can change the voltage, color, contact arrangement or included components.

Pushbutton and Pilot-Light Ordering Checklist

Before requesting a quote, collect:

• Manufacturer
• Product family
• Complete part number
• Pushbutton, selector switch or pilot light
• Momentary or maintained operation
• Mounting diameter
• Control voltage
• AC or DC
• Number and type of contacts
• Illumination requirements
• Color
• Legend
• Environmental rating
• Quantity
• Required date
• Preferred Revco branch
• Photographs or drawings

Frequently Asked Questions

Should I choose a 22 mm or 30 mm pushbutton?

Follow the existing plant standard or match the equipment being serviced. If no standard exists, compare panel space, glove use, product availability, environmental requirements and accessory options.

Can parts from two 22 mm product families be combined?

Not necessarily. The mounting diameter does not establish compatibility. Verify the manufacturer and product series for every operator, collar, contact block and light module.

How do I find the voltage of a pilot light?

Check the electrical drawing, equipment documentation and markings on the existing light module. If the voltage cannot be confirmed, have a qualified person identify the circuit.

Do LED pilot lights still need a voltage rating?

Yes. LED modules are designed for specific voltage ranges and current types. Confirm the complete rating before ordering.

Is a pushbutton head a complete pushbutton?

Often it is not. Modular assemblies may require a mounting collar, contact blocks, light module, legend and other accessories.

Can I replace a momentary pushbutton with a maintained one?

Do not make that substitution without confirming the machine’s control design. The change can alter how the equipment operates.

Can Revco help identify an existing device?

Provide the complete part number, manufacturer, photographs, voltage, mounting size and any available drawings. Revco can help search for a matching product or compatible replacement, but final suitability must be confirmed for the application.

Can I select emergency-stop parts from this guide?

No. Emergency-stop components must match the approved machine-safety design. Involve the equipment manufacturer, engineer or qualified machine-safety professional when the correct component is uncertain.

About Revco Lighting & Electrical Supply

Since 1978, Revco Lighting & Electrical Supply has supported electrical contractors, builders and facility professionals throughout Suffolk County.

Revco operates six Long Island locations in Southampton, East Hampton, Southold, Riverhead, Bohemia and Rocky Point. Visit theRevco locations pagefor current branch information or call 631-283-3600.