5 Factors to Consider When Choosing an Indicator

Stay Informed

Designing a control panel for your machine requires more planning than you might think. The sooner you make informed decisions, the better your product will be for your application and end-users.

But first, what’s in a name?

Indicator lamp, pilot light, status indicator — they all mean the same thing. It’s not what you call it that makes all the difference, but the planning that goes into it. From the type of lamp to the visual vocabulary, every decision can add up to optimal (or less than ideal) human-machine interaction.

Here are five things to consider when choosing the right indicator light for your control display.

1. Design Space and the Constraints of Your Panel and Device

The footprint of the panel and the overall size of the device have huge implications for how much room you’ll have to work with. Do you have enough real estate to include several indicators on the panel, each with their own status update? Or, will your indicator need to perform double- or triple-duty, signaling multiple states to end-users?

How the light source is connected to the panel also comes into play. Will you use a panel mount indicator or a circuit board with a light pipe? Will your device require multiple indicators?

Light pipes work best when:

  • The light needs to be transmitted a great distance or around a curve
  • Multiple indicators will be used on a single device

Panel mount indicators (PMIs) work best when:

  • The light doesn’t need to travel long distances or around curves within a device
  • There are only a few indicators on the panel

2. Working Conditions

How and where your device will be operated should be a guiding factor in determining the right indicator solution. For machines that will be used outdoors, moisture, humidity and operating temperatures must all be taken into account to ensure the optimal life of the equipment (as well as user safety). Industrial machines are often exposed to grease, dirt and sweat, but they also must be able to withstand high-vibration during operation.

Indoor devices can take a beating, too — especially in the food industry where exposure to abrasive cleaning chemicals is a key element to food safety. The harshest of these conditions can be addressed with the appropriate Ingress Protection (IP) rating. An IP rating of IP67 is sufficient for most industrial applications.

In addition to exposure to elements, how operators bend and move around the equipment is also an important consideration. Will users need to maintain status updates while standing off to the side? Will the sun be shining in their eyes while they operate the device?

If your device is portable, consider the importance of a wide-viewing angle. The shape of the lens face can also enhance (or hinder) viewing angle and daytime visibility. For example, a dome shape provides the widest viewing angle for visibility from multiple working positions by helping with side views.

3. Visual Vocabulary and HMI

Whether you’re designing a smart home device or an industrial machine, the end goal should be the same: simple, intuitive operation between the user and the HMI. Attaining the ideal human-machine interaction requires significant upfront research. The focus of your interface design and visual language should be user-centric, obtaining real input from actual operators whenever possible.

High-level user-centric design (UCD) principles to guide your thinking:

  • Focus on function and location of the device
  • Design for human error
  • Conduct usability testing with actual operators
  • Make the interface as simple as possible for the user

Keep in mind, the human brain processes visuals much faster than text. Research has shown that using color combined with icons allows for 37% faster reaction times than text alone.

Whenever possible, use colors and icons to communicate status updates during operation. What’s your visual vocabulary? Are you starting from scratch, or can you build upon common color cues familiar to your end-users?

Thanks to traffic signals, we all know green means go, while yellow means caution. Would these same basic color codes allow for the intuitive operation of your device? Consider the importance of incorporating your brand colors into the interface design. Will you use a single color to communicate multiple functions based on flashes, or use a single color for each status notification?


While the interface design is important, the user experience should guide every design decision related to your status indicator light should ladder back to how the machine and operator will interact.

4. Lighting Technology

There’s no one-size-fits-all for determining which type of lamp your indicator will need. From the power input and color selection to the working environment, there are several factors to consider when choosing between an incandescent, LED, or neon lamp.

Lamp Type

Average Operating Life






10,000 – 30,000 hours

Lowest initial cost

Puts out significant heat

Flexible voltage requirements

Fragile filament and bulbs


100.000 hours

Higher upfront costs

Cool operation

Low power consumption

Resists shock and vibration


40,000 hours

Low initial cost

Cool during operation

Low drain, high requirements of at least 70V

Reduced lifepan on DC; resists shock and vibration


Of course, the cost is always a factor. Choosing the lowest initial price may end up costing more in the long run with less-than-peak performance. Other factors, like maintenance, should be considered when selecting lighting technology.

LEDs are the future, thanks to a combination of long life, cool operation, low power consumption and ease of maintenance. LEDs are also available in high-voltage options of 110V and 220V (and even 240V) AC, as well as a range of colors. They are ideal for industrial applications where high vibration and extreme operating temps are all in a day’s work.

Neon lamps are a good fit for high-voltage operations, such as 110V AC or 220V AC. Like LEDs, neon lamps are rugged and not impacted by vibration or mechanical shock. These lamps can also handle frequent ON/OFF operations. And when driven with DC power, a neon lamp can be used as a reference voltage source while remaining stable at near 90V.

Incandescent lamps once ruled the day, but are now being phased out in many machines, based on lifespan, durability and heat output.

If you’re making any modifications to a design, consider retrofitting your lighting technology from incandescent to LED. In certain applications, these upgrades can add tremendous ROI for the end-user. Incandescent indicators can become brittle, overheat and frequently break, driving the need for ongoing maintenance and bulb replacements. In large-scale industrial applications, this level of downtime can add up. By replacing the incandescent bulbs with durable and long-lasting LEDs, your operators can enjoy maximum uptime and make maintenance virtually obsolete.

However, retrofits are also an ideal time to look at the overall control panel and determine if additional improvements are necessary. For one power generating station, VCC not only retrofitted energy-guzzling incandescents with LEDs, but we also streamlined the control panel by consolidating two single-color indicators into one bi-color pilot light.

5. Budget and Timing

In a perfect world, you’d have a blank check when it comes to specifying the right indicator for your device, and you’d get your indicators produced in the blink of an eye. In the real world, budget and time constraints can significantly impact the indicator you specify. However, it’s worth noting that many manufacturers can modify an existing product slightly, giving you the properties you want in a custom solution for a fraction of the price and lead time.

Remember, there may be a minimum order quantity (MOQ) associated with such requests. Be sure to consult with your manufacturer’s engineering team to determine if there’s a standard product or a modified standard solution that could give you what you need, and more importantly when you need it. Depending on the complexity, you could receive a custom design in as little as 4-6 weeks.

Putting It All Together

From the type of lamp to the HMI design, the pilot lights inside your device can play a significant role in the success and safe operation of your product. By asking the tough questions up front and collaborating with your manufacturer, you can get a solution more aligned with your exact specifications.



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With the largest offering of LED, incandescent and neon panel mount indicators on the market, VCC enables engineers to design-in exact solutions to meet their unique needs.