Interpretation ID: ConductorsPilkingtondrn

Joseph E. Poley, Senior Research Associate
Automotive Glass Technology
Pilkington North America, Inc.
2401 East Broadway
Toledo, OH 43619

Dear Mr. Poley:

This responds to your letter (Docket 15712-4) asking us to reevaluate the November 26, 2002 and July 23, 2003 interpretation letters that we issued to Mr. Larry Costa of Costa Industries, concerning whether Federal Motor Vehicle Safety Standard (FMVSS) No. 205, as amended on July 25, 2003 (68 FR 43964)(Docket No. 15712), further amended September 26, 2003 (68 FR 55544), January 5, 2004 (69 FR 279), August 18, 2004 (69 FR 51188), and July 12, 2005 (70 FR 39959), requires glazing fracture testing to be conducted with conductors or any other components attached.

We have developed the enclosed paper, "The Definition of Conductor in Fracture, Test 7 of ANSI/SAE Z26.1-1996, Incorporated by Reference into FMVSS No. 205". This paper clarifies the meaning of conductors and terminals and distinguishes between the terms.

If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or at (202) 366-2992.

Sincerely,

Stephen P. Wood
Acting Chief Counsel

Enclosure

The Definition of "Conductor" in "Fracture, Test 7" of ANSI/SAE Z26.1-1996,
Incorporated by Reference into FMVSS No. 205

March 2006
________________________________________

Background

A July 25, 2003 final rule incorporated ANSI/SAE Z26.1-1996 into Federal Motor Vehicle Safety Standard (FMVSS) No. 205.^[1]Section 5.7 of ANSI/SAE Z26.1-1996 has a fracture test specified for tempered glass and for multiple glazed units. The purpose of the fracture test is "to verify that the fragments produced by fracture of safety glazing materials are such as to minimize the risk of injury".To obtain fracture, a center punch or a hammer is used to break the glazing. To pass the test, the largest fractured particle must weigh 4.25 grams or less.

Section 5.7.2 of ANSI/SAE Z26.1-1996 specifies six production parts representing each construction type model number. The test specifies that specimens shall represent the model number considering "thickness, color, conductors" and shall be of the most difficult part or pattern designation within the model number.

On November 26, 2002 and July 23, 2003, NHTSA issued interpretation letters to Mr. Larry Costa of Costa Industries, concerning whether FMVSS No. 205, as amended, requires glazing fracture testing to be conducted with conductors or any other components attached. The letters involved the meaning of the phrase "most difficult part or pattern designation" within the model number. The November 26, 2002 letter was of the opinion that the provision in ANSI/SAE Z26.1-1996, under consideration in November 2002 for incorporation into FMVSS No. 205, would require manufacturers "to certify that glazing materials with conductors that may have localized annealing from a heating/cooling process would not produce any individual glass fragment weighing more than 4.25 g in a fracture test".The July 23, 2003 letter responded to an inquiry about "a subsequent soldering process or application of conductive adhesive [that] may result in changes in the structure of the glass, such that when the glass breaks, certain glass fragments (either attached to a conductor or free-standing) may exceed 4.25 g".The 2003 letter stated that, under the final rule adopting ANSI/SAE Z26.1-1996 issued that day, the glass fragments resulting from fracturing the glazing "would need to be tested with conductors attached, if such a condition represented the most difficult part or pattern designation within a given model number".

Requests for Correction

General Motors, Pilkington North America (PNA), PPG Industries, DaimlerChrysler and the Alliance wrote the agency asking us to reconsider the interpretations of the fracture test of ANSI/SAE Z26.1-1996 (Docket 15712). Their reasons included the following:

• It was not the intent of the authors of ANSI/SAE Z26.1-1996 that fracture testing be performed with soldered terminals attached. Further, it has never been industry practice to perform the testing with soldered terminals, or any other hardware item attached to the glass.
• Requiring testing after soldering of connectors or terminals would change the certification and testing process. GM stated that the basic manufacturing of glazing materials consists of: (1) cutting the glass to shape; (2) grinding edge work on the glass; (3) printing the paint band; (4) silk-screening the silver-frit conductors; (5) bending; and, (6) tempering. "When these steps are completed, the glazing has been shaped, sized, tempered, and where applicable, conductors applied. As contemplated by the wording of paragraph 5.7.2 of ANSI Z26.1-1996, it is at this stage that the glazing manufacturer has a piece that is suitable for all testing that relates to its physical and chemical properties.Soldering of connectors or terminals is one of those later steps that may not be performed by the glazing manufacturer".GM stated that companies that, at present, do not test glazing would become responsible for such testing. "The requirements of Z26.1 should be read in the context of the existing industry practices of glazing manufacture, testing, and certification. The 1996 revision changed the fracture test method, not the whole scheme of responsibility for testing and certification".
• There is no safety need to perform the fracture test with soldered terminals attached. There is very little likelihood that soldering would cause annealing, or that soldered terminals would change the weight of fracture test fragments. GM provided test data indicating that the presence of soldered terminals during the fracture test has no significant effect on fragment weight. GM stated that, for annealing to occur with tempered glazing, temperatures of 548-553 degrees C must occur over 15 minutes. At 505 degrees C, annealing requires more than 4 hours to occur. In contrast, normal soldering temperatures are typically 179-245 degrees C for less than 10 seconds for thermal soldering, or less than one second for resistance soldering. If soldering continues for longer or is done at higher temperatures, the glazing is likely to shatter from thermal shock or sustain other noticeable damage before becoming annealed.
• In current practice, individual glazing particles passing the fracture test requirement of 4.25 g would remain attached to the terminal in a cluster. According to PNA and the Alliance, the clusters pose no safety hazard because they are retained in place by the electrical wire. PNA stated that terminals have been attached to glazing for many years with no safety issue.

The parties asked NHTSA to reevaluate and clarify or correct the interpretations such that glazing would not be tested with soldered components attached.

Discussion

At issue is the use of the term "conductors" as used in ANSI/SAE Z26.1-1996 at 5.7, "Fracture, Test 7".The test specifies that specimens shall represent the model number considering "thickness, color, conductors" and shall be of the most difficult part or pattern designation within the model number.

We have determined that the meaning of conductors, as used in the fracture test, should be clarified. Our earlier correspondence on this issue used the term "conductors" to include material that is soldered on the glazing, which is more commonly known in the industry as "terminals".In its submission, General Motors stated:

The confusion surrounding this issue may stem in part from a lack of clarity about the distinction between conductors (the silver frit that is applied as part of the glazing manufacturing process) and terminals (which are soldered to the conductors after the glazing manufacturing process.)In its responses to Mr. Costa, the NHTSA appears to use "conductors" and "terminals" interchangeably.

We have determined, for the following reasons, that for the purposes of the ANSI/SAE Z26.1-1996 fracture test, "conductors" does not include soldered terminals.

• It was not NHTSAs intent in adopting ANSI/SAE Z26.1-1996 to dramatically change the manufacturing and certification responsibilities within the glazing industry. The industry does not conduct fracture testing of tempered glass with the terminals attached. We did not intend the final rule to create glazing certification responsibilities for suppliers that had never conducted glazing tests, which would be the case if soldered terminals were included in the fracture test.
• There has not been any shown safety need to conduct fracture testing of glazing with the terminals attached. GMs data support the finding that the presence of soldered terminals during the fracture test has no statistically significant effect on the fragment weight. NHTSA also examined two vehicles at the agencys Vehicle Research Test Center in which the rear window was fractured during a crash test. In both cases, the wire and terminal of the window defroster remained intact at the rear window location.
• The term "electrical conductors" is used in the definition of "electrical circuits" in SAE Recommended Practice J216, Motor Vehicle Glazing-Electrical Circuits, July 1995. As used in that definition, which relates to glazing applications, electrical conductors are "used to carry current for lighting, antennas to facilitate communications, special sensors, and heating to promote vision through the removal of moisture condensation, ice films, or snow".
• To gain a better understanding of the intent of ANSI/SAE Z26.1-1996, we contacted Mr. Richard L. Morrison, who was the acting chairman of the SAE Glazing Materials Standards Committee at the time of SAEs drafting of ANSI/SAE Z26.1-1996. Mr. Morrison stated that the term "conductors" in ANSI/SAE Z26.1-1996 was intended to refer to the ceramic frit that is typically silk-screened on to the glazing and not to the bus bar terminals.

Conclusions

• The term "conductors," as used in FMVSS No. 205s fracture test incorporating ANSI/SAE Z26.1-1996, means the metallic frit or wires (with electrical conductive properties) applied to glazing as part of the glazing manufacturing process. The frit is usually silver, but may be of any color. More specifically, "conductors" means the wires in or on the plastic interlayer of the laminated safety glazing material, elements integral with the surface of a safety glazing material, or coatings used to carry current for lighting, antennas to facilitate communications, special sensors, and heating to promote vision through the removal of moisture condensation, ice films, or snow. The term "conductors" does not apply to any metallic components, parts, or equipment (such as terminals) that unavoidably come into contact with glass glazing as a result of their electrical connection to the metallic frit or wires through soldering or other mechanical means and possible adhesive bonds to finished glazing for strain relief of the electrical connection.
• Many components other than terminals are attached to glazing, such as hinges, hinge plates and antennas. We conclude that these items are also not included in the fracture test.
• The glazing sample to be tested in the fracture test is chosen based on a consideration of thickness, color, and conductors. If the most difficult part or pattern contained conductors, the test would be conducted with the conductors, as that term is defined in this paper. Accordingly, we disagree with the Alliances statement in its letter requesting clarification of the fracture test (Docket 15712-9) that "nothing indicates that conductors or terminals must be present during testing." In certain cases, the "most difficult part or pattern" may contain conductors.

ref:205
d.4/7/06

^[1] Further amended September 26, 2003 (68 FR 55544), January 5, 2004 (69 FR 279), August 18, 2004 (69 FR 51188), and July 12, 2005 (70 FR 39959).