TLC #107 B – Federally Mandated “EFFECTIVE, PROJECTED, LUMINOUS LENS AREA” (“EPLLA”)
FMVSS #108 … and Common Sense … mandates that traffic directly following and adjoining must be exposed to fairly Contiguous, Large Lit Up Areas of properly directed “Light Rays” in order for adequate Brake, Turn and Lane Changing signal responses.
Federal Law mandates that single Brake and Turn Signals used on all Over 80” Wide Vehicles must have an “EPLLA” of at least 11-
Referring to the “Definition” Quotes from FMVSS #108:
§ 571.108 Standard No. 108; Lamps, reflective devices, and associated equipment
Effective projected luminous lens area means the area of the orthogonal projection of the effective light-
§ 571.108 … Section S6.3 The term ‘‘functional lighted lens area’’ in any SAE Standard or Recommended Practice incorporated by reference or by subreference in this standard, has the same meaning as the term ‘‘effective projected luminous lens area.’’
Note! That “EPLLA” … for Under 80” Vehicles … was increased from 5¾ in² to 7¾ in² by the below 1994 FVMSS #108 addition:
§ 22.214.171.124 Section … On a motor vehicle whose overall width is less than 80 inches:
(a) The effective projected luminous lens area of a single compartment stop lamp and a single compartment rear turn signal lamp, shall be not less than 50 square centimeters (7¾ square inches).
Unfortunately, the above Definitions and the terms “Effective Light Emitting Surface” and “Effective Projected Luminous Lens Area” (“EPLLA”) … are rarely understood by OEM Designers and Aftermarket Buyers.
Below, I’ve “tried” to write a couple of “clarifying paragraphs” … explaining the term “Effective Projected Luminous Lens Area” using my humble vocabulary, which hopefully makes the “EPLLA” mandates easier to visualize and understand!
Imagine the usable light output (“Rays”) from any source of Illumination (Bulbs or LEDs), which are directed thru a Fresnel Lens or are simply Reflected and/or Refracted using any combination of Reflective/Refractive Faceting, which results in specific, seeable, lit-
All the “Lit Facet Surface Areas” of a Test Lamp that are compliant to the official FMVSS #108 EPLLA Definition can be “officially tallied” towards meeting the mandated “EPLLA” requirements of FMVSS #108. If the total of all qualifying Lit Facet Surface Areas (pointing straight out) add up to at least 11-
Always keep in mind when tallying up officially qualifying “EPLLA” … you must disregard all “Faked”, “Non-
*Quote from above Definition
Also, as you can witness in real-
See TLC 111B for more details