Closeup of brow lights with markers on

Everything You Need to Know About Integrated Marker Lights

Marker light spacing and configuration is an easy topic to overlook, but it can have a big impact on your scene lighting package and the compliance of your apparatus.

For a long time, fire apparatus manufacturers have been responsible for the spacing and configuration of marker lights. Manufacturers are required to follow Federal Motor Vehicle Safety Standard 108 (FMVSS 108), which defines where and how marker lights must be installed.

FMVSS 108 Standards for All MPV, Trucks, and Buses ≥ 2032 MM in Overall Width

Clearance lamps 2 Amber On the front to indicate the overall width of the vehicle, or width of cab on truck tractor, at the same height, symmetrically about the vertical centerline

May be located at a location other than the front if necessary to indicate the overall width of the vehicle, or for protection from damage during normal operation of the vehicle

As near the top as practicable Steady burning
Identification lamps 3 Amber On the front, at the same height, as close as practicable to the vertical centerline, with lamp centers spaced not less than 6 inches or more than 12 inches apart As near the top of the vehicle or top of the cab as practicable Steady burning

In short, vehicles 2032 mm or more in overall width require:
  • Five marker lights on the front
  • The outermost two are considered clearance markers
  • The center three are considered identification markers
    • These let other motorists know, “Hey, a big vehicle is ahead!”
    • These are always a set of three (not four, not one, not two­—three)
    • They must be spaced between 6 and 12 inches apart
    • They must be amber if they’re forward-facing and red if they’re rear-facing
    • They must be on the same plane (mounted side by side, in a straight line—not broken up or bumped out)
    • They must be marked SAE P2 or SAE P3 to designate the type of light they are
    • They must be photometrically verified to be in compliance with SAE J2042

diagram of marker lights on fire truck cab

This can make the installation of forward-facing scene lights a challenge. In 2012, we wanted to install a linear extruded scene light on the face of an apparatus cab. We couldn’t do it because the marker lights were in the way. We thought about installing the light on the roof of the cab, but roof mounting causes shadowing, which we want to avoid. We developed a bracket to hang the light over top of the marker lights, and this worked fine – but, because it could have obstructed view of the marker lights, it wasn’t ideal. Finally, we reached out to our engineers to figure out how to integrate marker lights into our brow light on a different circuit.

After some work with engineering, we came up with a linear driver that allowed us to group our LEDs in configurations other than threes for our driver circuit—and the FireTech Brow Light with integrated marker lights was born.

Diagram showing spacing of marker lights on the Firetech Brow Light

Still, there were some concerns that the FireTech Brow Light would be considered an optically combined fixture and therefore not allowed by National Highway Traffic Safety Administration (NHTSA) standards.

A quick note about optically combined vs. optically grouped

Optically combined means two fixtures share a common optic – or, in other words, one optic with two uses.

In an optically grouped fixture, two independent fixtures with independent optics and independent LEDs/drivers share a common housing. In other words, each optic has only one use, but multiple optics share the same housing.

The FireTech Brow Light is optically grouped, not optically combined. This allows the marker lights to retain their identification function whether or not the scene lights are in use.

There were also concerns about an interpretation of NHTSA guidelines that prohibited mounting auxiliary lights next to marker lights. It’s important to note that in NHTSA standards, auxiliary lights have to be qualified as auxiliary to what. Since scene lighting is considered auxiliary lighting on the apparatus, some have incorrectly thought this interpretation applies to scene lights. However, the interpretation was referring specifically to additional (or auxiliary) marker lights.

The interpretation explained

If you put a bunch of extra marker lights next to your three ID marker lights, this would interfere with the intended visual signature laid out by the guidelines and invalidate the identification function.

Placing scene lights next to marker lights doesn’t interfere with their visual signature, however. Scene lights can’t be mistaken for marker lights, so the two amber clearance lamps on each side and three evenly-spaced amber identification lamps in the center would still be clearly visible.

Therefore, extra marker lights wouldn’t be allowed, but scene lights mounted next to your marker lights would be.

Because of the research we put into developing our integrated marker lights, we learned that there are a lot of things the industry commonly gets wrong. Trends we’ve seen that don’t pass regulations include:

  • Mounting a scene light in the middle with two marker lights on each side
  • Building a tray and pushing the center marker light on onto the tray
  • Mounting the light to the cab and pushing the center light down onto the face
  • Covering the center marker light altogether
  • Improper or missing markers
  • Improper optical spacing, with markers too close or too far apart

We developed the FireTech Brow Light to be the best solution to this issue, seamlessly grouping your scene and marker lights into one FMVSS 108 and SAE J2042 compliant fixture that eliminates the need to find complicated work-arounds.

Speak to an experienced scene lighting consultant

Have more questions about this topic, or about scene lighting in general?

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For the last 25 years, lighting manufacturers have been in a fierce competition to out-shine each other.  The focus of modern manufacturers’ has been one-upping the next with more lumens from their latest fixture.   Specifically with regard to LED technologies, we saw fixtures in the 10,000 lumen range initially, then 15,000 lumens, 5 or so years ago we saw manufacturers begin advertising light output 20,000 lumens + and more recently, manufacturers are touting 28-30,000 lumens.

When is enough, enough?  Does MORE lumens at the source equate to safer firefighters on the fire scene?

I just attended a Fire Apparatus Manufacturers Association event in Arizona (USA) where truck builders and suppliers get together to discuss trends in the industry.  One of the presenters, while discussing trade show effectiveness, asked us “imagine you’re a manufacturer of tools; drill bits specifically.  When you’re at the show, how do you explain your product to your customer?”  His discussion of the topic explained that instead of focusing on making strong or high quality drill bits, the message was really that you enable people to drill really good holes.  Nobody buys a drill bit because they love drilling, the buy a drill bit because they need a hole in something.

Using that logic, when we speak about lighting, we should be asking the question “What am I trying to accomplish?”  And “Do I need a really bright light, or do I need to be able to see to do my job after dark?”

My bet is the latter is more important than the former.  Assuming that statement to be accurate, lets explore some of the practical applications that can help accomplish that job.


  1. High quantity with less overall intensity.

Often, I am asked “what’s the most important factor to consider when lighting a fire scene?”  The answer is not how bright it is, but how consistent the light level is.  Think about walking inside a dim office from a bright outdoor location on a summer day: It takes your eyes a few seconds to adjust to the difference in light level.  Once adjusted, the lower intensity inside the building ends up being acceptable to work under.  The same principle applies at night.  If a firefighter near the apparatus goes from an extremely bright area on one side of the rig, through a darker spot, then back to a bright area, their eyes have to work to adjust and compensate for the changing light levels.

By using smaller fixtures placed more often around the body of the apparatus, versus just a few extremely high output fixtures, the highs and lows can be reduced.  Having a more even light pattern around the apparatus can be one of the most effective changes made in your fleet to improve nighttime visibility.  The cost of 4 small fixtures often ends up roughly the same as a fixture with a total cumulative lumen total similar to the set.

Pictured here are two examples of trucks.  The first is a truck with 4x 20,000 lumen scene lights installed midship on the body, one on the rear, and one on the brow edge.  The second truck is an example showing 10 smaller fixtures, 8,000 lumens each, spread out around the apparatus.  These two set ups produce similar total volume of light, put the placement of the light on the second truck is clearly advantageous.

These two configurations cost the same and create the same number of “Lumens”. The bottom image shows optimized placement.
  1. The COLOR of the light makes a difference.

One measurement not often mentioned in the fire service is the “Color Temperature” of the light produced by the fixture.  Color temperature, in its most simple form, is the measure of how amber/yellow/orange, or how white/blue/purple the light is.  Color Temp is measured in Degrees Kelvin.  2800k is typically in the amber color spectrum, while 5,000 is much more “white” and 7000k is blueish or purple.

In modern firefighting, choosing a fixture in the 5-6,000k range is usually a safe choice.  However, in some specialty applications this choice can be more impactful.  Rescue or hazardous materials response apparatus can benefit from a high color temperature.  The higher color temperature ~6,000k has a shorter wavelength and reflects off particulate (smoke, steam etc) much better.  In HAZMAT, its important to be able to tell if the railcar you’re working on suddenly vents a cloud of chlorine, or if the pile of spilled oxidizer substance is off gassing and reacting with the environment it is in.  High color temperature lighting can help responders see little changes faster.  Or make those changes more noticeable.

Inversely, imagine an application like fighting a wildland fire where dense organic smoke is often in and around the work area.  In environments with heavy saturation of particulate in the environment (dusty, smoky environments), using a color temperature with a slightly longer wavelength, 2800-4500k has advantages due to being less prone to reflect back and blind the operator.

Think about it this way:  when the sun rises and sets, the color of the light is typically orange.  At high noon, the light color is more white.  One of the principle reasons behind the change in perceived color of the sun is the particulate debris in the lower atmosphere filters out light in the shorter wavelengths, only allowing the amber and orange light to reach your eye when the length is greatest from you to the sun.  The whites and high color temperature light are reflected back towards the source.  If you are standing at the source, and only emit light in a spectrum that is not likely to bounce off the particulate into eh atmosphere, the likelihood of bounce back and glare can be reduced.

  • High color temperature in rescue environments where dexterity is important
  • Low color temperature in environments where dense organic smoke, filled with particulate debris, can be used to reduce bounceback
  1. Better thermal management yields sustained light output

Both fixtures advertised as “20,000lm”. The bottom fixture is very thin and degrades more than 40% over 1 hour due to thermal runaway. The top fixture is thick and more efficient, only degrades 17.25% in the same time frame.

One factor often overlooked by fire apparatus manufacturers and specifying comities is the ability of the fixture to manage its thermal load.  People gravitate towards thin fixtures because they are easier to carry, easier to manipulate and raise on poles/tripods.  However, when a cross section of fixtures from the industry is measured, the fixtures with more thermal mass, and better ability to dissipate heat typically outperform in the long run.  Some very popular fixtures get so hot, the measured light output after 30 minutes can be measured with up to 45% degradation.

If you were to take a 150 watt circuit board out of any manufacturers fixture, and attach it to the housing of every manufacturer’s fixture, you would notice a significant difference in performance based only on the design of the housing.

How can you ensure you get maximum bang for your buck?  Request thermal degradation data from the light manufacturer before you specify it!  Or, set the test up in your fire station.

Take a light fixture, plug it in to a known power source, put a light meter on the ground at a pre-set distance from the fixture, and write down the measurements every 5 minutes for an hour.  After 1 hour, if the number has stopped dropping, you can consider the fixture “thermally saturated” and calculate the percentage of reduction in output.  The number on the meter is less important, but the percentage difference from the highest to the lowest is what’s important.

All fixtures will have some degree of degradation; 15-20% is normal.  Anything higher than that indicates a problem with thermal management, which will ultimately reduce the lifespan of the circuit and cause unpredictable light levels on your fire scene.


  1. Get the lights up in the air!

WillBurt NightScan Light Tower with 4x XL-200 LED fixtures shown. Light elevated to eliminate glare and improve visibility.

When designing a lighting package, one of the common questions asked is “where should I mount the fixtures?”  The short answer is, most of the time, as high as possible.  Think about the natural shape of the human face:  two eyes, symmetrically placed on either side of the scull, recessed back in towards the center of the upper cranium.  Humans have eyelids, eye lashes, and eyebrows.  If we use this shape to our advantage, those structures on the face can act like the bill of a hat to prevent glare from hitting us directly in the eyes.  Elevating the light in the air shining down on the fire scene not only reduces unnatural shadows, but also takes advantage of the natural shape of the human head to keep light out of the eyes of the first responder.

Interested in learning more?  Check out this video explaining the science behind why elevation is so important when working with Scene Lighting!

In conclusion, scene lighting can be a complicated topic.  If you break it down and change your perspective, solve the problem “how do I help my firefighters see at night” not “how many lumens can I pack in to this space on my apparatus” and you are sure to see an improvement in the your crew’s nighttime effectiveness.

Sam Massa is the president and Chief Technologist for HiViz LED Lighting and the FIRETECH brand.   Sam is an American Firefighter/EMT and Hazardous Materials Technician based in North Carolina, as well as a technical specialist in areas of scene lights.  Sam is a member of the North American “Fire Apparatus Manufacturers’ Association” and has provided input and public comment on language adopted in to the NFPA 1901 Standard for Automotive Fire Apparatus.  HiViz LED Lighting can be found online at and Sam reached at


PTO Generator with Quartz Halogen Scene Light
240v Quartz Halogen LED scene light with PTO Generator installed and running

By Sam Massa 12/26/2015

Swapping old 120v/240v AC halogen fixtures to 12v DC LED fixtures 

Many fire departments elect to swap their scene lighting over from 120v/240v AC (generator powered) to 12v DC when doing an LED scene light retrofit.  We see customers all the time who have large PTO generators on their apparatus with the sole purpose of firing the couple of 240v quartz scene lights placed around their trucks.  While there are numerous benefits to having an apparatus with an on board generator, if it ever fails, the repair or replacement cost is often significantly higher than the cost of replacing the AC infrastructure with 12v LED scene lights.

An important consideration when converting from 120v AC fixtures to 12v DC fixtures is that it is not always possible to simply re-route and and re-use the old wiring attached to a new 12v power source.  In simple terms, as voltage is decreased amperage is increased proportionally.  Increased amperage in a wire that is too small will cause that wire to heat up and can cause a fire, in addition to loosing voltage as the power makes its way to the fixture.  Too much voltage drop in the wiring will cause the light to operate incorrectly.

The amount of CURRENT the 12v DC fixtures draw, while still less WATTAGE is often significantly higher than the previous AC scene lights.  They ARE still more efficient and still draw less power overall. There is a long technical explanation for why, but as firefighters or equipment installers the explanation does not matter as long as we know the above statement to be true.

So what!?

When customers see issues with their AC to DC retrofit installations, the great majority of the time, the problem can be directly attributed to the fact that the new load applied to the old circuit is drawing more current than the infrastructure was originally designed to support.

Wire Gauge Chart_wide

AC or DC power, the laws of physics are still the same.  Watts divided by Volts equals Amps.  Amps and the total distance from the battery or power source are the only numbers that really make a difference when designing the electrical system (and sizing the wiring appropriately).

The simple question to ask is “are the old wires I am planning to re-use heavy enough to support the current of the new system?”  If you dont know, check out this simple quick-reference chart to help you size your wire appropriately.

Here’s a hypothetical

The HiViz LEDs Fire Department owns a 2001 Rescue truck with a 12kw 240v generator.  On a call one night, the generator stopped working and after the mechanic looked at the truck, they were told it would require replacement.  A new generator costs $15,000.  The truck has 6 scene lights on it, each 1500w.  They want to replace the 1,500w scene lights with the FT-SL-15 fixture but want to hook it up using DC power vs AC.  The total fixture replacement cost is around $7,200 and the FD will be adding a 2kw suitcase generator for $1,500 for the odd jobs that require an AC power supply.  The FD will save around $7,200 in equipment cost going this route and will eliminate their lighting maintenance cost if they install the solution correctly.

One of the guys on the lighting committee says he can just re-use the old wiring and can have the lights installed in an hour.  An older member read this article and thinks otherwise.  Here’s some math that would help them figure out if they need to run new wiring to the fixtures


1500w fixture, divided by 240v = 6.25 Amps.  The total wire run length is about 25’  to each fixture.

The FT-SL-15 will be operated at 12v.  The fixture draws 150 watts.

150 watts divided by 12 volts equals 12.5 Amps per fixture- TWICE the amperage of the previous 1500w fixtures.

During manufacturing of the truck, the wiring that was installed to support the previous AC fixtures was most likely sized to match the 6.25A / fixture current draw.  It is very likely the fire department would have issues with their installation if they simply re-used the wiring.  They elect to take the truck to their local fire truck dealer and have all heavy-gauge wiring run for a total out the door cost of around $1,500.  At the end of the day, the HiViz Fire Department was still able to save $5,700 and install a superior lighting solution with a lifetime warranty, compared to the $15,000 quoted cost to replace their broken PTO generator.

If you are interested in learning more about retrofitting LED Scene lights on your fire apparatus, check out our Scene Lighting products page or contact us to schedule a demo from one of our FireTech LED Scene lighting experts.


About the Author:

SAM MASSA is the President and Chief Technologist for HiViz LED Lighting, a manufacturer of specialty scene lighting equipment with a primary focus on the Fire and Emergency Services market.  Sam is a North Carolina Firefighter / EMT and community contributor / active participant providing public commentation from the Scene Lighting industry to the NFPA 1901 technical committee.  Sam has 11 years of entrepreneurial experience running small business and advising industries on technical topics ranging from Fuel Systems to LED Scene Lighting.

HiViz LED Lighting is located in Lillington, NC and is a member in good standing with the Fire Apparatus Manufacturer’s Association.  For more information about how FireTech Brow LightScene LightWork Lights, and Compartment Lighting solutions can be implemented in your fire department and on your fleet, contact HiViz LED lighting here.

a simple comparison to help firefighters grasp seemingly complex topics in lighting.

 By Sam Massa

CCCC Graduation Day
Graduation Day at CCCC after the recruits completed a nearly 6 month Certified Firefighter Program

Firefighters often get a bad rap in the technical communities as being more like cavemen than the scholarly “academic” types.  After all, our group does run in to burning buildings when everyone else is running out.  What most don’t understand, however, is that firefighters do NOT typically run in to structures blindly without a very calculated assessment of the situation and an application of a finely honed set of skills that they have mastered during their training.

To read a list of some things a certified firefighter is required to know: reading smoke… understanding pyrolysis and thermochemical decomposition…knowing advanced hydraulic theory and on-the-fly calculation of friction loss… a variety of topics in the emergency medical field… just to name a few… It would be reasonable to assume the profession was more akin to rocket science than “merely” putting out fires.

Its amazing to me how a certified firefighter will – despite all their knowledge of specialized technical topics – go completely cross eyed when the topic of lighting a scene is brought up while we are working on their truck spec.  I mention “lumen, lux, and efficacy” and its as though I’m speaking a rare foreign language to my group.

After 5 years of attempting to unsuccessfully explain these three topics to firefighters, while sitting in a Hose Streams and Appliances class, I had a revelation:  Lighting theory and spraying a fire hose are VIRTUALLY IDENTICAL.

Check this out:

The above 6 images show a fixture configured with 6 different optics. The LUMENS does not change but the light in any given area does (Lux)
The above 6 images show a fixture configured with 6 different optics. The LUMENS does not change but the light in any given area does (Lux)


“Lumens” is the measurement of total comprehensive output from a light source.  This measurement refers to light at the source- at the fixture itself- and does not help the user gain any sense of how well the fixture will illuminate the scene.  It’s a “total power” type of rating more so than a measure of how much light is on the target.


“Lux” is the measurement of how much useable light is hitting what the fixture is aimed at.  Typically, because this is such a finite measurement, it is coupled with an “area.”  For instance; “Light A” will illuminate an area on the ground 30 feet away from the fixture that is 10’ wide by 10’ long to 50 lux.  A fixture can not be rated in “lux” like it can be “lumens” because lux is measured on whatever the fixture is shining on, Lumens is measured at the source.  Lux is a metric measurement, Foot-Candles is Imperial.

Water spraying from a hose line. Similar pattern to using a "spot" optic in a light fixture.
Water spraying from a hose line. Similar pattern to using a “spot” optic in a light fixture.


In firefighting terms, think of a hand-line flowing 250GPM of water.  If the appliance is an adjustable fog nozzle, changing the pattern from straight stream to fog does not change the GPM or flow rate, just the spread and direction of the water. “Lumens” can be equated to the GPM, the optics are the nozzle pattern, and the amount of water hitting any given point is the “Lux”.

In straight stream mode you’ll get either a lot of distance or a high intensity on something very close, but when you open the pattern up, the fog pattern disperses that water into tiny droplets that cover a larger area with less intensity in any given location.  In lighting, a spot light gives you a lot of intensity in a small area or great reach, but by simply changing the optics to flood optics, you can disperse the light over a much broader area for more even overall scene lighting.

With Efficacy, think about how Friction Loss affects how you’d pump an apparatus.  Just as things like distance, diameter, and vertical rise can skew your total output and flow rate, in lighting, things like thermal management and optic efficiency can affect how likely it is to achieve the expected effect of the total measured “Lumens.”  As a fixture gets hot, the output from the LEDs will suffer.  It is absolutely critical that the device manufacturer have a plan in place for how the fixture will regulate its own temperature (or just like the way friction loss would affect an entry team as they advance up multiple flights of stairs) you will see a significant drop in light output as the fixture gets hot.


With this basic understanding of the most fundamental components of lighting, an educated Apparatus Spec Writing committee can make a more informed decision on the fixtures and configurations they need to get their job done.  This will result in purposefully chosen fixture placement that is not a guess, and after installation will provide superior illumination in the areas firefighters need light in order to maximize safety while they are on scene.


About the Author:

SAM MASSA is the President and Chief Technologist for HiViz LED Lighting, a manufacturer of specialty scene lighting equipment with a primary focus on the Fire and Emergency Services market.  Sam is a North Carolina Firefighter / EMT and community contributor / active participant who provided valuable public commentation from the Scene Lighting industry to the NFPA 1901 revision’s technical committee.  Sam has 11 years of entrepreneurial experience running small business and advising industries on technical topics ranging from Fuel Systems to LED Scene Lighting.

HiViz LED Lighting is located in Lillington, NC and is a member in good standing with the Fire Apparatus Manufacturer’s Association.  For more information about how FireTech Brow LightScene LightWork Lights, and Compartment Lighting solutions can be implemented in your fire department and on your fleet, contact HiViz LED lighting here.