Clearance Lamps & Conspicuity Tape
By Colin Holthaus, NATM Technical Director
Compliance with trailer lamp and reflector requirements helps continuously advance trailer safety and it can help NATM Members pass their consultations making them eligible for NATM decal purchases immediately after their consultation. For these reasons, it is important to periodically review the Federal Motor Vehicle Safety Standards (FMVSS) for trailer lamp and reflex reflector requirements. Two commonly missed items during compliance consultations are clearance lamps and conspicuity tape on the trailers that require them. Trailers 80 inches wide or wider, no matter the gross vehicle weight rating (GVWR), must have front clearance lamps, rear clearance lamps, and three rear ID lamps. The three ID lamps in the middle of the rear of these trailers are meant to indicate the presence of a wide trailer. The front and rear clearance lamps’ purpose is to show the trailer’s width. The three ID lamps must be red, have a lens coding of P2 or P3, and must be mounted on the rear of the trailer – centered horizontally spaced 6 inches to 12 inches apart facing rearward. The ID lamps must be mounted at the top of the trailer, but can be mounted lower if the door header is narrower than 25 mm. The rear clearance lamps must be red and have a lens coding of P2, P3, PC, or PC2. There must be one of them installed on each side of the trailer that indicate the trailer’s width and may NOT be combined with tail lamps. They must be mounted at the widest point – symmetrical on the rear or near the rear of the trailer facing rearward. The rear clearance lamps must be mounted as high as practicable, but they may be mounted lower only if ID lamps are at the top. The front clearance lamps must be amber and have a lens coding of P2, P3, PC, or PC2. There must be one of them on each side of the trailer that show the trailer’s width. They must be mounted at the widest point – symmetrical on the front or near the front facing forward and mounted as high as practicable. Requirements for front clearance lamps and front side marker lamps in amber can be met with the same individual lamp if the lamp is mounted on a 45-degree angle. However, in this case, the lamp must have a lens coding PC or PC2, if it is to serve as both a front side marker lamp and a front clearance lamp. P2 or
P3 lens coding in this application will not serve as meeting both requirements for a front side marker lamp and a front clearance lamp, even if mounted at a 45-degree angle. The lens coding is most easily verified by obtaining the product description for the lamps the trailer manufacturer ordered, which can usually be accessed from the lamp supplier’s website. If the trailer manufacturer’s intent is to mount the amber lamp at a 45-degree angle to meet the front side marker lamp and the front clearance lamp requirements with one lamp, they should double check to make sure they are utilizing PC or PC2 lamps in that application. In addition, front clearance lamps are to be mounted “at the widest point” of the trailer. Trailer manufacturers often ask what constitutes the widest point of the trailer for this purpose. Years ago, NATM adopted the industry standard that the widest point of the trailer is within six inches of the extreme width of the trailer. This means that if a trailer has 10-inch fenders sticking out on each side of the trailer, and the front and rear clearance lamps are mounted on the body of the trailer rather than the fenders, the clearance lamps will not be compliant because they are not mounted within six inches of the extreme width of the trailer. Trailers with a design where the fenders stick out from the sides in this manner can correct this issue with lamp options that are specifically designed to be mounted on fenders. One popular style is a dual front and rear clearance lamp option that mounts to the top of the fender or the side of the fender. The front half is amber, and the rear half is red. Another popular way some trailer manufacturers meet the front and rear clearance lamps requirements is by utilizing small, individually mounted, ¾ inch bullet style lamps. In the same fashion as the dual front and rear clearance lamps, the bullet lamps must be installed so the amber lamp faces forward, and the red lamp faces rearward. Tables X and XI below list the side marker lamp and clearance lamp photometry requirements, which can also be accessed in Title 49 CFR 571.108 on the electronic code of federal regulations website, gov.ecfr.io.
Table X—Side Marker Lamp Photometry Requirements Where a side marker lamp installed on a motor vehicle less than 30 feet in overall length has the lateral angle nearest the other required side marker lamp on the same side of the vehicle reduced from 45° by design as specified by S7.4.13.2, the photometric intensity measurement may be met at the lesser angle. (1)
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The photometric intensity values between test points must not be less than the lower specified minimum value of the two closest adjacent test points on a horizontal or vertical line. (2)
Where side marker lamps are mounted with their axis of reference less than 750 mm above the road surface, photometry requirements below 5° down may be met at 5° down rather than at the specified required downward angle. (3)
Table XI—Clearance and Identification Lamps Photometry Requirements
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The photometric intensity values between test points must not be less than the lower specified minimum value of the two closest adjacent test points on a horizontal or vertical line. (2)
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When optically combined with a stop lamp or turn signal lamp, this maximum applies on or above the horizontal.
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Where clearance lamps are installed at locations other than on the front and rear due to the necessity to indicate the overall width of the vehicle, or for protection from damage during normal operation of the vehicle, they need not meet the photometric intensity requirement at any test point that is 45° inboard.
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Where clearance lamps or identification lamps are mounted with their axis of reference less than 750 mm above the road surface, photometry requirements below 5° down may be met at 5° down rather than at the specified required downward angle. (1)
(3)
(4)
Another commonly missed item during NATM Compliance
understanding and visualizing these requirements:
Consultations is known as the conspicuity tape three-inch rule.
https://one.nhtsa.gov/cars/rules/standards/conspicuity/Trlrpstr.html. The
Trailers 80 inches wide or wider with a GVWR of 10,000 lbs. or
electronic code of federal regulations website, gov.ecfr.io has additional information on Title 49 CFR 571.108 that is beneficial in understanding lamp and reflector requirements.
more must have red and white conspicuity tape marking the sides of the trailers, the rear lower body marking, the bumper bar or underride marking if applicable, and the rear upper body markings of the trailer. The tape must be rated DOT-C, DOT-C2, DOT-C3, or DOT-C4. The three-inch rule is one aspect of conspicuity tape application that is commonly overlooked by trailer manufacturers. The edge of red conspicuity tape shall not be closer than 75 mm to the edge of any amber lamp and the edge of white conspicuity tape shall not be closer than 75 mm to the edge of any lamp. For the sake of simplicity, 75 mm is just shy of three inches, hence the term “three-inch rule”. In other words, the red and white conspicuity tape running across the rear lower body marking of a trailer cannot have the white portion of the tape be closer than three inches to the edge of any lamp. This means the employee applying the tape can either cut the tape back at least three inches from the lamp, or plan out the tape application so the tape starts with the appropriate color that will gap the tape out in a manner that will only allow for red tape to come up next to a red lamp. The same rule also comes into play for the conspicuity tape on the sides of the trailer. During consultations, NATM Compliance Consultants often find that production managers and employees working in the final stages of the trailer manufacturing process are simply unaware of the three-inch rule. For any trailer manufacturer building trailers 80 inches wider or wider and 10,000 lbs. GVWR or more, this is a good topic of discussion in production meetings. The three-inch rule is best illustrated by Figure 12-2, Trailer Conspicuity Detail II, which can be viewed to the right as well as on the electronic code of federal regulations website, gov.ecfr.io. For trailer manufacturers that have questions about other lamp and reflector requirements, the NHTSA trailer lamp, reflector, and conspicuity tape chart is beneficial in
Table I-b, required lamps and reflective devices for all trailers is available at the eCFR website gov.ecfr.io and can be accessed in the 2018 NATM Guidelines in the B-6 Section on lighting, reflectors and conspicuity. For additional assistance with lamp and reflector requirements, contact NATM Technical Director Colin Holthaus at (785) 272-4433 or Colin.Holthaus@natm.com.