NFPA 1901 Zone C Rear Lighting – Part 2

By Bill Adams

Part 1 ended inferring the rear ends of most pumpers are congested work areas. And it questioned whether apparatus manufacturers’ standard locations for chassis and warning lights could hinder fireground operations. This part continues that discussion while espousing the concept of “looking outside the box” when evaluating subjective and opinionated viewpoints. Minor changes in light locations and sizes could improve firefighter safety and operational efficiency.

The National Fire Protection Association NFPA 1901 Standard for Automotive Fire Apparatus (NFPA 1901) and the Department of Transportation Federal Motor Vehicle Safety Standard 108 (DOT/FMVSS108) mandate rear lighting requirements. They’re referred to herein as NFPA and DOT lights. Zone C is an NFPA designation for the area covered by rear warning lights.

Access Ladders

Safety conscious purchasers specify permanently affixed “out and down” access ladders mounted above the rear tailboard. They’re usually bolted to a full-depth and full-height side compartment. Available in various widths, the most common is 18 inches (photos 4, 5, 6 and 7). Regardless if deployed or stowed, access ladders partially obscuring NFPA or DOT lights might not be problematic unless there’s an accident and the light blockage is legally challenged as a contributing factor.

Photo 4. Photos 4 through 8 are by the author.


Lights mounted directly behind a ladder at eye level pose a problem—especially at night. High-intensity warning, scene, work, or traffic directional lights shining directly into the eyeballs is distracting, unsafe, and possibly injurious.

Equipment Access

Equipment historically mounted for easy access on the outside of pumpers is now stored in compartments, possibly slowing operations. One example is the hydrant bag or whatever is used to hold tools to dress a hydrant. It was often hung on the rear panel; or mounted on the tailboard; or stored in a small, open compartment located between the frame rails.

I’m not advocating eliminating compartments. I am promoting mounting or securing some essential equipment to the rear panel or tailboard reachable from the ground. Firefighters should have access to as much equipment as possible without climbing onto the rig or opening compartment doors. If the compartment door opens into a traffic lane, it is inherently dangerous. A supply line’s leading end, especially with a preconnected gate, should also be easily accessible. Nozzles on “high” rear preconnects could be mounted on the rear panel; ditto for preconnected ground monitors. Minor tools such as spanners should be readily available and not buried in a compartment. Many reasons for “not enough room” are due to lights’ footprints and locations.

Tailboards, formerly known as rear steps when firefighters could ride there, were generally 18 inches to 24 inches in depth, full width of the rig. On a 96-inch-wide body, there are 12-16 square feet of flat surface where portions could be used to mount equipment—providing the equipment does not block the lights. Many apparatus designs today downsize or eliminate the tailboard probably for fear someone would actually stand on it while responding.

Facts & Fallacies

Earlier postings mentioned warning lights and standardization can be confrontational and emotional topics. They still are. Light mounting locations adopted by some manufacturers and explained as “the standard locations” are not necessarily the only locations mandated by NFPA and DOT. Yet they are generally accepted without question by the fire service.

Manufacturers (OEMs) prefer consistency in the fabricating process. Some might believe purchasers requesting changes and modifications are challenging their manufacturing expertise. Most purchasers don’t care; they sign the check and usually want things “their” way. Choosing the footprints and locations for NFPA and DOT lights should be based on operational considerations while remaining within the parameters of the regulatory agencies. Doing so can maximize space and make it safe and efficient for firefighters to operate.

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Rear DOT lights are very often supplied by the same manufacturer supplying the warning lights. It doesn’t have to be. DOT lighting does not have to be the same size and have the same efficacy as NFPA lights. DOT and NFPA lights don’t have to be vertical; or immediately adjacent to each other; or within a common enclosure.

The following dimensions are approximate because manufacturers don’t always specify if measurements reflect the actual lens or if they include a mounting enclosure. Rectangular-shaped Zone C NFPA light footprints range from 2-inches x 4-inches (8 square inches) to 7-inches x 9-inches (63 square inches), yet both can be NFPA compliant! The NFPA is not concerned with the size of a light. It is concerned with its efficacy. Its effectiveness or brightness is what counts. Small-sized rear DOT lights include a 4-inch diameter round fixture (12.5 square inches) and a 2-inch x 6-inch oval/rectangular shape (12+ square inches). In comparison, a 6-inch diameter round light has 28¼ square inches.

This link is to a light manufacturer of DOT compliant lights. It lists almost two dozen combination stop, turn, and taillights in various configurations.

A web search for “North American Standards and Specifications” found the following two items when accessing the Truck-Lite Corporation:

*“DOT/FMVSS 108 says that some lights must be mounted as “high as practicable or as far apart as practicable.” What is “practicable?” The NHTSA has stated that the vehicle manufacturer has the responsibility to choose the best mounting location “in light of the particular design/configuration of the vehicle involved” and they will not contest it unless it is “clearly erroneous.” Recently, Canada has started to enforce the word practical as meaning “capable of being done.” Note: NHTSA is the National Highway Transportation Safety Administration, part of the DOT. NFPA 1901 also uses the terminology “as close as practical” when mandating light locations.

*“What is the ‘12-Square Inch Rule’?  On December 1, 1991, the NHTSA made effective the final ruling regarding the 12-Square Inch Rule. This ruling requires that the total luminous lens area for a stop and turn lamp must not be less than 75 square centimeters (11.625 square inches) when used on vehicles over 80-inches wide.” Unless there are exceptions for fire apparatus, those regulations are law. Ask your favorite OEMs—they’ll know—they have to follow the law. You can also ask if DOT lights have to be as blistering bright as NFPA lights.

What’s this all Mean?

Rear DOT light footprints can be much smaller than the commonly used 4-inch by 6-inch NFPA lights. Rear DOT lighting must be between 15 inches and 72 inches from the ground, and rear NFPA lower-level lights must be between 18 inches and 62 inches. DOT and NFPA lights do not have to be installed next to each other.

As long as light locations are within DOT and NFPA parameters, they can and should be located to work to the fire department’s advantage to get more usable room on the rear end. Think outside the box!

Alternative Locations

The attached diagrams for illustrative purposes only reflect a common pumper flatback design incorporating full-depth high-side compartments on both sides with rear slide-in ground ladder storage in the upper right-side compartments. Approximate side compartment depths are 28 inches. The rear step compartment is about 44 inches wide, and its height is irrelevant for this narration. It is 24 inches from ground to the top of the tailboard, and the hose bed side sheets extend 14 inches above the compartment tops. Dimensions and exact mounting locations can vary between manufacturers and methods of construction. The lights shown are surface-mounted.

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Using an arbitrary footprint of 2-inches x 4-inches for DOT and NFPA lights, the three layouts illustrate how different footprints and locations can provide greater utilization of the rear surface of the apparatus. In all diagrams, the upper auxiliary set of stop/tail and turn signal lights are this writer’s personal preference. They are not DOT mandated.

Diagram #1 shows four identical vertical light configurations from top to bottom: stop/tail, turn signal, warning, and back-up. All are surface-mounted as close as physically possible to the outside body edges and body top or tailboard.

Diagram #2 shows horizontal stop/tail and turn signals mounted on the rear panel as high as possible. On the bottom below the tailboard on each side are horizontally mounted from outboard to inboard: stop/tail, turn signal, warning, and back-up lights. They are recessed (protected) within a channel structure bolted to the bottom of the tailboard. Photo 8 shows a similar concept on a side rub rail. Or, the treadplate rear step itself can have an additional downward brake underneath to mount the lights.

Diagram #3 has the same upper horizontal stop/tail and turn signals as #2. The lower lights, with the same configuration as #2, are recessed each side within in a full width channel or angle bolted on the downward surface of the tailboard.

Diagram 1. Diagrams are provided by Frank Riccobono, a Western New York salesman for HME-Ahrens Fox and 4Guys Fire Apparatus.

Diagram 2

Diagram 3

Points to Ponder

*The diagrams reflect a concept showing minimum required NFPA and DOT lighting in compliant albeit somewhat different locations. Not all manufacturers’ lights are NFPA or DOT compliant when mounted in a vertical position. Check with the light manufacturers all apparatus vendors might not know.

*Upper-level auxiliary turn signals and stop/tail lights are not required. If not desired, use the location(s) for extra warning, scene, back-up, or work lights, or eliminate them altogether.

*After locating where equipment might be mounted, add as many extra NFPA, work, or scene lights as you want. How many Zone C lights are too many? Photo 9 shows twenty-three (23). As long as DOT and NFPA minimum requirements are met, who cares if the backend looks like someone projectile-vomited two dozen lights on it? Efficiency is what counts.

*Zone C upper level NFPA lights must be “brighter” than lower level NFPA lights. (See Ken Menke’s last statement below.) Some warning light manufacturers might require a larger size or multiple upper level lights to be compliant.

*Upper level NFPA lights do not have to be on the same horizontal plane. NFPA 1901 only says upper-level optical warning devices shall be mounted as high and as close to the corner points of the apparatus as is practical to define the clearance lines of the apparatus.

*Upper level NFPA lights do not have to be the same size or type. NFPA 1901 only requires the lights meet minimum optical requirements and are certified to be compliant. A rotating light on one side and a flasher on the other side will work as long as the total required output is met. The same applies for a 4-inch diameter round light on one side and a 7-inch x 9-inch rectangular light on the other side.

*Lower level NFPA lights also do not have to be on the same horizontal plane, or be the same type, or be the same size. Their optical centers must be between 18 and 48 inches above level ground. They also don’t have to be made by the same manufacturer as long as someone provides certification that in combination the lights meet the minimum photometric requirements.

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*When installed in a common enclosure, the oft-supplied-vertically-stacked four 4-inch x 6-inch DOT/NFPA lights are a hair over 18-inches in height, which prohibits installing a step above it.

*If purchasers believe—for whatever reason—they need larger size warning lights, then go for it. The NFPA does not specify a maximum number of warning lights allowed. Nor does it mandate a maximum size or brightness (efficacy). Nor does it mandate that common sense be used when specifying them – although maybe it should.

Photo 8

A Difference of Opinion

I asked Ken Menke III, owner of the PowerArc warning light company, to objectively comment on my idea of mounting rear warning lights recessed into or just below the tailboard. He didn’t hold back: “As long as your proposed lower light layouts comply with color and height requirements, corner position markings (as close as practicable), flash rates and optical power for that zone, you have no compliance issues. However, the layouts may not follow good design practice.”

He continued: “A warning light 18 inches above ground level may only be effective for a vehicle directly behind the apparatus, but a warning light at three to four feet above ground level provides signal to the second or third vehicle behind the apparatus. Lights hung under tailboard and the side running boards are the first devices to be covered in road grime. How effective is a light covered in road debris, snow, or mud, or perhaps half full of water? Any non-standard mounting position will increase the cost of installation. The apparatus manufacturer has added labor, engineering, and wiring.”

In regard to a small-size footprint, Menke added: “Uniquely designed lights normally cost more. If it is not a common light footprint, you might be restricted to one or two suppliers. Additionally, a smaller size light may limit lighting options such as the unit’s intensity and providing moving components. Smaller warning lights generally produce less optical power (are not as bright) and they will have less beam spread based on the smaller optics for a smaller footprint. Depending on their location, they may be harder to install and service.”

Photo 9 is courtesy of Ken Menke III of PowerArc.

He ended it with: “NFPA compliant Zone C lower-level lights can be small. The Zone C lower-level lights only need to be 19% as bright as the Zone C upper level lights. Bottom line is it’s all about balance and compromise. It is functionality vs. cost vs. safety vs. performance. Don’t forget, some apparatus manufacturers may refuse to use the product. Until the new standard is published (NFPA 1900) one can only predict what changes, if any, will be made to warning light requirements.”


NFPA 1901 – 13.8.9 says: “The front optical warning devices shall be placed so as to maintain the maximum possible separation from the headlights.” I wonder why it doesn’t say anything about warning light separation from DOT or scene lighting at the rear?

In the NFPA 1901 Appendix A., it states: “Under typical conditions, the specified optical warning system provides effective, balanced warning. In some situations, however, the safety of the apparatus can be increased by turning off some warning devices. For example, if other vehicles need to pass within close proximity to the parked apparatus, the possibility of distracting other drivers can be reduced if the headlights and lower-level warning lights are turned off. In snow or fog, it might be desirable to turn off forward-facing strobes or oscillating lights to reduce visual disorientation of the apparatus driver.” I wonder why it doesn’t specifically say anything about turning off rear lower NFPA lights—even when driving? Maybe the new NFPA 1900 standard will address both.



By Bill Adams Part 1 ended inferring the rear ends of most pumpers are congested work areas. And it questioned whether apparatus manufacturers’ standard locations for chassis and warning lights could hinder fireground operations. This part continues that discussion while espousing the concept of “looking outside the box” when evaluating subjective and opinionated viewpoints. Minor changes […]

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