Lighting

Why can't I place marker lamps at the bottom of my trailer?
How can I spot non-compliant products?

As you are likely aware, the three marker lamps at the top-rear of the trailer, mounted around the center line of the vehicle, are called "identification lights." Their purpose is to alert following drivers that the vehicle with these lights is a commercial...

What affects the lifespan of LEDs?

Efficient design of the circuit is the key to ensuring that the LED lamp assembly will be robust and last for a long time.  One key factor is to ensure that the discrete LEDs are operated below their maximum rating.   The Truck-Lite Engineering...

Is the lifespan reduced if the LEDs are frequently turned on and off?

No. In fact, at Truck-Lite’s R&D lab, the original prototype LED stop/turn/tail light has been blinking since 1998!

What is the lifespan of LED lighting?

As you may know, LED lights are monochromatic.  Monochromatic means that red LEDs only produce red light, amber LEDs only produce amber light... but now there are white LEDs. White light is often produced by using a blue LED covered by a ceramic...

Can I still drive a vehicle with LED lights if some of the LEDs go out?

This is open to interpretation. It is generally assumed that, if several diodes fail on a light, but most of the light remains lit, you are okay to drive the vehicle. Truck-Lite strongly recommends replacing lights with failed diodes as soon as possible...

Do the TOP markings really need to be at the top?

Yes, it is an obligation for legal compliance.

My customer wants to add some auxiliary lights (i.e. Illuminated signs, deceleration lights, decorative lights). Are these legal?

Yes, provided they do not render inoperative any device in compliance with FMVSS-108, negatively affect the performance of required equipment or create confusion or misunderstanding of lighting signals. Feel free to contact Truck-Lite if you have...

My customer wants to use a light for a side turn that isn’t listed for that function. Is this OK, seeing as how side turns aren’t required anyway?

Be careful that it doesn’t violate some state laws regarding color or location. If it is also used as a side marker, the function must be listed on the lens code.

FMVSS-108 says that some lights must be mounted “as high as practicable.” What is practicable?

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...

Are there any special lighting requirements for vehicles hauling flammable or explosive materials?

There are no special federal requirements, as FMVSS-108 covers all over-the-road vehicles. Some states or municipalities have regulations, but these cannot supersede FMVSS-108; they can only add to it. Truck-Lite’s lights and wiring systems have...

Is SAE or DOT lettering required on lights?

Lettering is not required by NHTSA (FMVSS-108) except for headlights and conspicuity tape. The Federal Motor Carrier Safety manual mentions that some lights should be marked SAE but this is not enforced. Truck-Lite marks all their lights with SAE and...

What is the 12 Square Inch Rule?

On December 1, 1991, the National Highway Traffic Safety Administration (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 light must not be less than ...

What are combination marker/clearance lights, and how do I mount them?

A combination marker/clearance light is one light doing the work of two. It must be at a 45-degree angle (on corners) to be legal. It needs to be marked “PC” in the lens code. For further information, contact Truck-Lite.

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