1. Requirements For High-Voltage AWM For Use In TV Receivers (Example: Style 3239)

Numerous materials were added to Tables 7.1 and 7.2 in UL 758. These were previously located in the original Section General and were not moved into the standard until the recent revision on October 31, 2003. By adding these materials to UL 758, all of the applicable requirements are in one place but there is more than one set of requirements for the same material.

In order to eliminate multiple requirements for the same material, effective October 31, 2004, Tables 7.1 and 7.2 will be withdrawn. The tensile and elongation requirements found in Section 50 of UL 1581 and Tables 7.1.1 and 7.2.1 in UL 758 will be in effect.

UL will rely on the samples picked up for Follow Up service testing until October 31, 2004 to determine compliance with the new requirements.

Prior to October 31, 2004, Follow-Up samples will be tested in accordance with the requirements in UL 1581 and Tables 7.1.1 and 7.2.1 in UL 758. If a nonconformance in physical properties is obtained, the results will be checked against the requirements in Tables 7.1 and 7.2. If complying results are found, the sample will be considered acceptable. However, manufacturer shall be reminded that effective October 31, 2004, the requirements in UL 1581 and 7.1.1 and 7.2.1 will be required.

2. Silicone Rubber

Currently, there are two sets of requirements for silicone rubber. The requirements for Class 22 silicone rubber are found in Table 50.210 of UL 1581. These requirements apply to silicone insulated wires which:

1. are covered with a fibrous covering,
   
2. are for use in a jacketed cable, or
   
3. are installed where not subject to movement or mechanical abuse,
   or where totally enclosed.

The requirements found in Tables 7.1 and 7.2 of UL 758 apply to silicone insulated wires which do not have a covering or jacket and may be installed in a normal handling area.

Effective October 31, 2004, styles 3546, 3354, 3355, 3365, 3380, 3535, 3540, 3541, 3547, 3548, 3570, 3579, 3587, 3600, 3603, 3650 and similar styles will be withdrawn. These styles, which reference Class 22 silicone, do not meet one of the three criteria listed above.

Figure 1 shows the differences between the requirements for braidless silicone rubber found in UL 758 and those found in UL 1581 for Class 22 silicone.

Figure 1
Physical Properties Requirements for Silicone Rubber in UL 758 and UL 1581

Temperature rating

3. Production-Line Dielectric Test

Section 45A for Production-Line Dielectric Test has been added to UL 758. The dielectric test shall be performed by the manufacturer on 100 percent of production where a metallic shield is placed over insulated conductors.

The insulation on the individual wires in the finished assembly shall be capable of withstanding at room temperature a test potential stated in Table 28.1 (extracted in Figure 2) applied between all interconnected conductors and all the interconnected shields. The test potential is to be supplied from a suitable 2 kVA or larger test transformer. The test potential is to be gradually increased from zero until the required test voltage is reached and is to be held at that value for one minute.

Figure 2
Dielectric Voltage-Withstand Test Potentials