UL 758 the Standard for Safety of Appliance Wiring Materials FAQ
Are style pages being retained?
Style pages continue to be used as the main method of describing individual AWM constructions. It has been rumored that they would be deleted.
In the development phase of UL 758, it was proposed that style pages be eliminated, in favor of a "Ratings and Use Code" system. For example, Style 1015 would become "I B 105C 600V H." Such "Ratings and Use Codes" corresponded to voltage and temperature ratings, mechanical abuse ratings, flame ratings, etc. However, in discussing this issue with various groups, such as UL staff, manufacturers, end-product industry groups, etc., it was determined that style pages provide unique identifiers for individual AWM constructions. This is very similar to the way people can easily recognize and visualize a SJTW Flexible Cord, or a 4-Pair 24 AWG Type CMR Performance-Verified Category 5 cable. Therefore, UL elected to keep style pages, along with making them available on UL's Web site.
You can also view style pages and current listings online.
If style pages are being maintained, what is changing?
Each style page will now reference UL 758 as the Standard used for determining the requirements for each style. This includes requirements such as standardized tensile strength and elongation requirements, spark testing requirements, and dielectric voltage withstand requirements.
Why was UL 758 developed?
UL 758 was developed to consolidate requirements. Over the 40 years the category has been in existence, many people have had different interpretations of how to evaluate the wire. These procedures evolved over time. In addition to the 124-page Section General, many "desktop" standards or outlines were used to evaluate wire constructions. UL 758 was formed so that all customers and users of AWM were aware of the test protocol and requirements, and to maintain consistency.
How different is the format of the Standard from the AWM Section General?
The two documents are very different.
As manufacturers and UL staff requested clarification on various issues over the years, policy statements and test methods were added to the Section General. Sometimes they were added in chronological order, in order to reduce the renumbering of the pages. Although a table of contents was available in the AWM Section General, referencing specific requirements was time consuming, as similar topics were located on different pages in the Section General.
UL 758 follows the standardized format for UL's Standards for Safety:
- Foreword -- Includes UL corporate policy statements regarding the Standard and its use.
- Introduction -- Includes the scope of the Standard, an explanation on the units of measurement used.
- Construction -- Contains the most generic requirements for individual components of the product. For AWM, this would include conductor requirements, insulation and jacket, and other general requirements.
- Performance -- Contains all test requirements determined necessary for a particular product to qualify under UL's AWM requirements.
- Manufacturing and production tests -- These are the tests that are required of the manufacturer, typically on 100% of all production.
- Marking -- How the product is to be marked in order to be considered as Recognized AWM. The marking section includes surface print marking, and marking of the engineering tags that accompany the finished AWM. UL labeling (Recognition Mark) requirements are specified in the Follow-Up and Inspection Instructions (FUII), which is contained in each manufacturer's Follow-Up Service procedure.
Below are the individual paragraphs and page number of UL 758, as of February 9, 2004:
2.2 Units of measurement
2.3 Undated references
5.3 Size and cross-sectional area
5.4 Metal coating
6 Optical fiber member(s)
12 Cable assembly
13 Overall jacket
Tests for thermal and chemical properties
14 Physical properties of insulation and jacket, unaged and air oven aged
15 Physical properties of insulation and jacket, oil immersion aging
16 Physical properties of gasoline resistant insulation and jacket
17 Physical properties of insulation and jacket, sunlight resistance
18 Conductor corrosion test
19 Deformation test (thermoplastics and Class XL only)
20 Flexibility test after air oven conditioning
21 Heat shock test (thermoplastic materials only)
22 Cold bend test
23 Delamination test
24 Shrinkback test -- special rating tv wires only
25 Ozone resistance test -- special rating tv wires only
Tests for mechanical properties
26 Crush resistance test
Tests for electrical properties
27 conductor resistance test
28 dielectric test, method I
29 Dielectric test, method II
30 Dielectric test, method III
31 High-voltage DC wire dielectric voltage-withstand test, method I
32 High-voltage DC wire dielectric voltage-withstand test, method II
33 High-voltage cut-through test, special-rated TV wire only
34 Short-term insulation-resistance test in water at room temperature (wet rated AWM)
35 Long-term insulation-resistance test in water at elevated temperature (wet rated AWM)
36 Temperature correction factor (wet rated AWM)
37 Capacitance and relative permittivity tests (wet rated AWM)
38 Stability factor (wet rated AWM)
Tests for flame properties
39 Horizontal flame test for use rating I
40 Vertical flame test for use rating II
41 VW-1 flame test
42 FT-1 flame test
43 FT-2 flame test
Manufacturing and production tests
44 Test for continuity of conductors
45 Spark test
45A Production-line dielectric test
46 Surface marking of AWM
47 Markings on tag, reel, or carton
48 Multiple markings
How will the format for the Follow-Up Service procedures be affected by the use of UL 758, instead of using the AWM Section General?
There is little effect on the format of the AWM Follow-Up Service procedures. There are more changes to the overall documentation system for AWM. You can review the summary of each component of the AWM documentation system, with changes marked in bold.
What are the major technical changes to each AWM style?
There are few technical changes. Instead, most of the requirements are consolidated in UL 758. Here are the most significant changes with affect marking or testing requirements:
- No permanent identification (e.g., marker threads or surface print) are required for cables rated 90 C or higher.
- The value for insulation resistance for wet-rated wires was harmonized to 2.5 megohm based on 1000 feet (0.75 megohm based on 1 km) at room temperature (20 C or 68 F). Long-term insulation resistance values were taken from UL 83, the Standard for Safety of Thermoplastic-Insulated Wires and Cables, and incorporated into UL 758.
- Dielectric-voltage withstand test mandrel sizes have been changed in some cases from 3/16 inch in diameter to values based on two times (2x) the overall diameter of the sample under test.
- Individual styles and their respective facing pages have their physical properties requirements revised or removed to align themselves with the various generic material requirements in UL 1581, the Standard for Safety of Electrical Wires, Cables and Flexible Cords.
How do you determine which tests are required on a particular style number?
The Subject 758 bulletin, dated February 15, 2001, describes how to use the information on a style page to determine what tests are required from UL 758. It also describes how to determine what tests are required on a proposed new style.
What if I find an error in UL 758?
Due to large variety of styles currently covered by UL 758, there may be situations where a requirement is not specifically applicable. UL 758 has undergone several revisions since the original publication based on comments from users of the Standard.
Is UL 758 going to be harmonized with CSA 22.2 no. 210?
There are currently no harmonization efforts underway. It has been determined that it would be prudent to wait until UL 1581 is harmonized with its Canadian equivalent CSA 22.2, No 0.3 since so many of the requirements in UL 758 reference UL 1581.
Can any style be rated VW-1?
Yes, any style can be rated and marked VW-1 as long as it meets the requirements in the standard. Wires and cables marked VW-1 are subject to monthly sampling by your local field representative.
What if I have specific questions regarding AWM, and I need to contact someone at UL?
UL's testing offices have trained wire and cable personnel that can answer your questions. Conformity Assessment Services personnel can answer questions regarding testing needs and requirements, such as qualifying a manufacturer to manufacture a particular style ("New Work Investigations"), and test methods. Typically, Follow-Up Service Inspection issue contacts can answer questions regarding labeling and marking issues, and FUS inspection policies and procedures. In some instances, the personnel are the same.
For manufacturers, it is best that they contact the personnel show below at their reviewing office, where they normally submit their products for the new work investigations.
How are the braidless silicone requirements in Tables 7.1 and 7.2 of UL 758 applied to current styles?
If a style page specifies Class 22, or if the style page has a use statement which says "... where not subject to movement or mechanical abuse" or the like, or if the construction has a braid, Class 22 requirements, found in Table 50.210 of UL 1581, apply. If the style does not have any of the constraints listed above, the requirements in Tables 7.1 and 7.2 apply.