TAKING THE MYSTERY OUT OF APARATUS WARNING LIGHT REQUIREMENTS

TAKING THE MYSTERY OUT OF APARATUS WARNING LIGHT REQUIREMENTS

BY WILLIAM C. PETERS

A few weeks after instructing an apparatus course, I ran into one of the attendees while at an apparatus manufacturer`s factory. After exchanging pleasantries, we both got down to the business at hand, performing final inspections on our new pieces of apparatus.

After about one hour, my friend asked for my advice. The apparatus that he was inspecting was a “limited edition” model. For a very reasonable price, a functional NFPA-compliant pumper was being provided. The only drawback in purchasing this “standard model” was that very few options or changes could be made.

When the firefighter inspected the finished product, he had a valid complaint about the warning lights. As part of the upper-level warning light system, the apparatus was equipped with a strobe lightbar with red and blue filters on the cab roof and two amber halogen rotating lights mounted on the rear stanchions. The manufacturer`s representative indicated that those specific colors were “required” by the new NFPA apparatus standard and that any changes would void the lighting manufacturer`s certification of the system.

In the state where the apparatus was going to be used, blue lights were used exclusively by the police vehicles, and amber rotators were only permissible on tow trucks and highway repair vehicles. Red was the only acceptable color for fire apparatus warning lights.

A month later at another manufacturer`s facility, inspecting team members were upset that one of the side warning lights on each side of their new apparatus was amber. Their sales representative indicated that it was “required” in the new NFPA 1901 standard.

While both of these stories are true, the basis of the misunderstanding lies in meeting the optical warning light requirements of the NFPA standard with specific equipment. While there is no excuse for the person responsible for specifying apparatus not to obtain, read, and understand NFPA 1901, Standard for Automotive Fire Apparatus– 1996, I will attempt to explain some of the key points in un-derstanding apparatus warning lights.

LEVELS AND ZONES

Apparatus warning lights are installed to provide a maximum optical warning to traffic in the vicinity of the apparatus, whether the unit is responding or parked on-scene. The needs while requesting right-of-way (responding) focus on the front of the apparatus and are obviously different than when parked on-scene and the rear is blocking the right-of-way.

To fulfill these needs, the standard divides the apparatus in two different ways. An upper and lower warning light level is defined, and each side of the apparatus is identified by a letter. The four zones are determined by drawing lines through the geometric center of the apparatus at 45-degree angles. In easier terms, while viewing the apparatus from the top, imagine an equal “X” drawn through the center. The front zone is considered “A” and, moving clockwise, the right side is “B,” the rear is “C,” and the left side is “D” (see illustration on page 97).

LIGHT CONTROLS

A master optical warning light switch that activates all of the warning lights must be provided. Nothing in the standard prohibits you from specifying individual warning light switches to control lights or groups of lights downstream of the master switch; however, they must all be activated by the master switch. Appendix A of the standard points out that there might be instances in which reducing some of the warning lights could enhance safety such as shutting off forward-facing strobes or oscillating lights in snow or fog to reduce disorientation of the driver or when traffic passing closely by is being blinded by lower-level lighting.

The purchaser might also consider an electronic se-quencer. This device generally activates and deactivates warning lights at one-second intervals. This reduces the possibility of damaging the electrical system by introducing or re-moving a major electrical load suddenly.

The job of selecting the re-sponding mode vs. the on-scene configuration is handled automatically by the electrical system sensing the parking brake position. When the brakes are released, the apparatus is in the “requesting right-of-way” mode, which directs more optical power to the front. When the parking brakes are applied, the optical warning system reduces power to the front and increases warning to the rear for blocking the right-of-way.

While this automatic system relieves the operator of manually switching lights off and on when he arrives at the scene, this arrangement is not “written in stone.” The standard specifically allows the purchaser to specify a method of modifying the two signaling modes if necessary (9-8.6).

LARGE AND SMALL APPARATUS

In defining the number of warning devices, their power output, amperage consumption, and placement, the standard defines two sizes of apparatus. If the apparatus has a bumper-to-bumper length of 22 feet or more or has an optical center on any optical warning device greater than eight feet abovegrade, it is considered a large apparatus for the purpose of warning light requirements. Small apparatus obviously have smaller dimensions than those defined for larger units.

PERMISSIBLE COLORS

First, you should understand that the standard does not dictate what colors you must have in any zone; it only identifies what is permissible in each zone, depending on the signaling mode. It further states, “within the constraints imposed by applicable laws and regulations.” If your local laws prohibit or require certain colors, choices in the type and number of lights must meet the zone measurement requirements.

The basic requirements of the standard are easy to understand. Red or blue can be used in any zone in either signaling mode. Yellow can be used in any zone when in the blocking mode but is not permitted in the front (Zone A) while responding. White is just a little more tricky. During response, it can be used in any zone except to the rear (Zone C). All white warning lights must shut down when the apparatus is in the blocking mode.

OPTICAL POWER OUTPUT

Understanding the permissible colors is not really that difficult. The difficult part is trying to meet the Minimum Optical Power Output Requirements with specific light sources and specific colored filters.

The flash energy requirements listed in the standard are measured in candela-seconds per hour. Measurements of the optical devices are taken at 19 data points, 45 degrees each side of center and five degrees apart, which fans out a total of 90 degrees. This information is then used in a mathematical formula that combines the intensity of the light source and the flash duration to produce a candela-seconds per-hour rating. Specifiers who select lighting packages need not be concerned about measurement numbers, as the lighting manufacturers have performed the re-quired tests to ensure that their systems meet the required values.

On “large apparatus,” each zone (A,B,C, and D) has an output measurement requirement for the upper and lower levels. The lower-level devices on all sides (Zones A,B,C, and D) each require 150,000 candela-seconds/minute of output (measured at the optical center of the device), regardless of whether the apparatus is moving or parked. The upper side zones (B and D) also remain constant at 400,000 candela-seconds in each mode.

The upper front (Zone A) and upper rear (Zone C) change significantly, depending on whether the apparatus is “calling for right-of-way” or “blocking right-of-way.”

While responding, Zone A (front) requires 1,000,000 candela-seconds of output and Zone C (rear) requires 400,000. When the apparatus arrives on-scene, the front zone (A) is reduced to 400,000 and the rear zone (C) increases to 800,000.

Remember, these are all minimum requirements. Nothing in the standard prohibits you from producing 800,000 candela-seconds of output to the rear while both responding and on-scene, except possibly the amperage limitations that will be discussed later.

On “small apparatus,” the output measurements are somewhat different and are measured using the combined power of all optical sources mounted on both the upper and lower levels in each zone. Small apparatus is consistent with the larger apparatus in requiring a 1,000,000 candela-second in Zone A while responding and 800,000 in Zone C while blocking but requires only a combined total of 200,000 to the sides.

The warning lights must be of sufficient number and arranged so that the failure of any single light source does not create a measurement point in any zone without a warning signal at a distance of 100 feet from the center of the apparatus. The minimum flash rate of any individual light shall be 75 flashes per minute, and the minimum number of flashes at any measurement point shall be 150 flashes per minute (for the whole zone).

WARNING LIGHT PLACEMENT

On larger apparatus, the upper-level warning lights should be mounted as high and as close to the corner points of the apparatus as practical and within the specified height defined by the device manufacturer. This will help define the clearance lines of the apparatus and provide a more distant warning.

The lower-level lights should be as close to the corner points of the apparatus as practical, with the optical center of the light between 18 and 62 inches abovegrade. Note the phrase “as practical.” If your apparatus design does not provide room at the lower rear corner to mount a warning light, the rear portion of the wheel well might be as close to the corner point as practical and will comply with the intention of the standard.

In addition, at least one midship optical warning device is required on each side of the apparatus. Additional midship lights are required on longer apparatus, such as ladder trucks, when the distance between the centers of the lower-level lights exceeds 15 feet.

All optical warning devices include the requirement that the unit be constructed or arranged to avoid projecting the light either directly or through mirrors into any driving or crew compartment. This means that where 360-degree rotating lights are used, the rear of cab lightbars must be “blacked out” on tillered trucks or apparatus with a raised crew-cab roof that has forward-facing windows.

On smaller apparatus, the upper-level devices are to be mounted as high as practical but not higher than eight feet. They can be combined into one or more enclosures (such as a lightbar) and are permitted to be mounted on the cab roof or another convenient location.

The lower-level warning lights should be mounted as close as practical to the front corner points of the apparatus with the optical center between 18 and 48 inches abovegrade.

WHY ALL THE DIFFICULTIES?

So far, the standard`s requirements are fairly easy to understand; however, two very important considerations cause difficulties for purchasers and suppliers: the amperage limitations and the optical light source in conjunction with colored filters (lenses).

First, on large apparatus, the minimum optical requirements shall require no more than an average of 45 amps for the operation of the upper- and lower-level warning devices. This is considering one midship light. If additional midship lights are required to meet the 15-foot measurement, an additional five amps per pair are allowed. On small apparatus, 35 amps are allowed for the operation of the devices.

Considering that some larger lightbars can consume 60 or more amps alone, this amperage restriction requires some serious calculations.

What you must understand is that this amperage measurement is to meet the minimum optical output requirements. Nothing prohibits you from using that 60-amp lightbar, but it must be capable of meeting the optical output requirements for the zone with only a limited number of lights operating. Once all the zone measurements are satisfied with an average of 45 amps, other warning devices can be added as desired.

This is much like specifying the number of discharges on a fire pump. A 1,000-gpm pump requires four 212-inch discharges (or combination of discharges) to satisfy the full pump capacity. Nothing in the standard prohibits the specifier from adding as many additional discharges he feels are necessary to enhance the capabilities of the apparatus once the minimums have been satisfied.

As one participant at a recent conference excitedly stated after this explanation was given, “So that means if you`re facing the wrong way on the Gowanus Expressway (in New York City) at rush hour, your front warning lights don`t have to shut down to comply with the standard!”

While the amperage limitation is sometimes difficult to meet, there is some flexibility in this requirement in Paragraph g of Section 9-3.2, which outlines the minimum continuous electrical load of the apparatus.

The “minimum continuous electrical load” is defined as the amperage required to operate the following:

Engine and transmission.

Clearance and marker lights.

Radio.

Step, work area, and 50 percent of compartment lighting.

Minimum optical warning system while in the “blocking” mode.

Pumps, aerial device, and hydraulic pumps.

Other warning devices and electrical loads defined by the purchaser as critical to the mission of the apparatus.

The alternator is required to have a minimum output at idle to supply all of the items defined in the continuous electrical load. If additional warning devices are required to meet a critical need, a proportionally large enough electrical system must be provided to supply them.

Anyone who doubts this interpretation should review A-9-8.12.6, which indicates, “Optical warning systems drawing more than 45 amps might necessitate modification of the electrical system specified in Section 9-3 to supply the additional power required.”

Go ahead and specify whatever your favorite lights are, but you should also consider “load managing” the optical warning devices that are not part of the minimum requirements.

Electronic load management automatically removes electrical loads when the system is in a state of discharge and reintroduces them when it has recovered. This could be critical for an apparatus operating at a fire that experiences a low-voltage condition. With the extensive use of electronically controlled engines, transmissions, and pump governors, a low-voltage condition could shut the engine down, endangering members on hoselines or in other critical areas of the emergency scene.

Now that the amps have been managed, the next problem to consider is what is going to produce the light source for each of the warning devices. The two primary warning light sources are halogen incandescent and gaseous discharge (strobe). Each performs differently, depending on the color of the filter (lens) placed in front of it.

Both light sources perform about the same in the white mode (about 87 percent) output. In yellow, they are also close (around 60 percent). The red and blue filters create more of a problem relative to the light source. Strobes far outperform halogen in blue (38 vs. 13 percent), because there is more blue in the color spectrum produced by the strobe flash. The exact opposite is true of red. Red halogen lights outperform strobes by a good margin (26 vs. 17 percent), because more red is in the color spectrum of the halogen light source.

The wattage of the light source also contributes to its measurable optical power. Although many devices look alike, they may have a different rating, depending on the power being produced by the light source.

Some devices require specific colors to meet or exceed the standard`s minimum requirements. In the first example at the beginning of this article, the forward lightbar required some blue to meet the forward (A) zone requirements, and the power output of the light source of the rear rotators required amber lenses to provide enough output to satisfy the rear (C) zone measurements.

With some manufacturers` products, one red and one amber rotator are required in the upper C zone. If your state prohibits amber in this location, a third light centered under the hosebed will provide enough output to satisfy the zone with two red rotators.

You can avoid these problems by disregarding the way you used to specify warning lights and relying on the lighting manufacturers` packages.

CERTIFYING THE SYSTEM

The standard requires that the apparatus builder meet the compliance requirements with one of three methods.

1. A certification that the system was installed within the requirements of the device manufacturer and referencing the optical source test reports provided by the lighting system manufacturer.

2. Certification by mathematical calculations based on test reports of the lighting devices manufacturer and performed by a qualified person.

3. Actual measurement of the lighting system after installation on the apparatus.

Of the three methods allowed, the easiest for the apparatus builder and the customer ensuring that the standard`s minimum requirements are met is a certification by the lighting manufacturer. This has led to the “packages” referred to in this article.

For the lighting manufacturer to certify a package, all of the upper- OR lower-level devices must be produced by the same company. You can specify a Brand A- compliant upper warning light package and a Brand B lower-level package on the same apparatus (with the exception of the smaller apparatus that rates the upper and lower levels together). Also, once you satisfy the minimums, you can add additional lights from any manufacturer.

GETTING HELP

Fear not–help is available! All of the major lighting manufacturers have brochures that list their products and the combinations available to meet compliance in each zone. They also have qualified personnel available to answer questions and solve the problems of complying with the NFPA standard as well as state and local regulations.

The major apparatus manufacturers also have personnel on staff who can answer your questions. I would caution you to avoid the advice of some people who do not understand the whole concept and provide erroneous opinions. Unfortunately, this might include your local apparatus sales representative. If you have a question, go to the source!

While this chapter of the standard prompted some initial confusion, the goal of the Electrical Task Group was to provide a safer environment for fire apparatus users. Much of the information used to produce this part of the standard came from actual visual observations of lighting techniques by a cross-section of fire apparatus manufacturers and purchasers (of which I was one). We have certainly come a long way from one roof-mounted beacon and a couple of flashers at the front, sides, and rear! n

Before the 1991 edition of NFPA 1901, the requirement for warning lights on fire apparatus was only “a red flashing light, or lights visible through 360 degrees in the horizontal plane.” The 1991 edition expanded the requirements to include a pair of warning lights below windshield level, a pair at the rear of the apparatus, and intersection lights at the front corners. (Photo by Ron Jeffers.)

(Top left) The current standard requires warning lights at the upper and lower corners at the front of the apparatus. Pictured here, the lightbars cover Zones A (front), B (side), and D (side) in the upper zones. In the lower level, the forward-mounted lights cover Zone A and the intersection lights, B and D. (Photo by author.) (Top right) Rear warning lights include the rotators located at the upper corners covering Zones C (rear), B (side), and D (side) and lower flush-mounted lights facing to the rear and side to mark the outline of the apparatus. (Photo by author.) (Bottom left) After you have met the minimum requirements, you may add additional lights. The amber strobe shown here is of a different manufacturer than the lower lights, which are installed as part of an NFPA-compliant “package” and certified by that manufacturer. (Photo by author.) (Bottom right) The requirement for a midmounted side light for Zones B and D that is within 15 feet of the front and rear side lights sometimes presents a mounting problem. This manufacturer mounted the lights below the side, which is allowable as long as the optical center of the light is more than 18 inches above the ground. (Photo by author.)

(Top) With some models of warning devices, a third light is required in Zone C (rear) to meet the zone total requirement while blocking the right-of-way. An amber directional arrow can help meet the requirements while directing traffic away from the apparatus. (Photo by author.) (Bottom) With some lighting products, one red and one amber light will meet the upper rear zone requirements. If your jurisdiction does not permit this color combination, check with the lighting manufacturer to discuss acceptable variations. (Photo by Ron Jeffers.)

n WILLIAM C. PETERS is battalion chief, supervisor of apparatus, and a 22-year veteran of the Jersey City (NJ) Fire Department. He is a member of the NFPA Technical Committee on Fire Apparatus and the Fire Engineering editorial advisory board. Peters is the author of Fire Apparatus Purchasing Handbook (Fire Engineering Books, 1994), two chapters on apparatus in The Fire Chief`s Handbook, Fifth Edition (Fire Engineering Books, 1995), and the booklet Final Farewell to a Fallen Firefighter: A Basic Fire Department Funeral Protocol.