Understanding the UL 746 Series of Standards

What are the UL 746 Standards?

UL 746 covers a wide range of material properties, including mechanical, electrical, thermal, flammability and other safety-related characteristics. The series is divided into several parts, each focusing on specific aspects of material evaluation: UL746A, UL746B, UL 746C, UL 746D, UL 746E, UL 746F, UL 746G, UL 746H UL 746R and UL 746S. 

Key components of the UL 746 series:

Short-term property evaluations

UL 746A, the Standard for Polymeric Materials - Short Term Property Evaluations, provides a framework for assessing the mechanical, electrical, physical, chemical resistance and flammability properties of materials over short durations.  

At UL Solutions, we offer a comprehensive suite of mechanical testing methods designed to deliver reliable, actionable data applicable across a wide range of products and use cases. Our testing capabilities include evaluating key material properties, such as:

• Dimensional stability at elevated temperatures
• Density and moisture content in polymers
• Scratch resistance of surfaces

Using advanced temperature test chambers, we simulate accelerated aging to uncover the long-term effects of heat exposure. This process helps identify irreversible changes in the composition, surface characteristics and structural integrity of plastics and components. 

Flammability testing for plastic materials

UL Solutions conducts two primary preselection test programs to evaluate the flammability characteristics of plastic materials:

• Flame spread and extinguishing behavior
  This program assesses whether a material tends to extinguish or propagate flames after ignition. It follows the UL 94, the Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, which is harmonized with international standards including IEC 60707, IEC 60695-11-10, IEC 60695-11-20 and ISO 9772/9773.
• Electrical ignition resistance
  This program evaluates a material’s resistance to ignition from electrical sources, and its surface tracking behavior. Testing is conducted under UL 746A, aligned with procedures in IEC 60112, IEC 60695 and IEC 60950. 

Long-term property evaluations

UL 746B, the Standard for Polymeric Materials - Long Term Property Evaluations, focuses on how materials age and degrade over time, especially when exposed to prolonged thermal stress.

At UL Solutions, we use advanced temperature test chambers to simulate accelerated aging, allowing us to observe the long-term effects of heat exposure. This process helps identify irreversible changes in the composition, surface characteristics and structural integrity of plastics and components — providing valuable insights into material durability and performance over time.

Use in electrical equipment

UL 746C, the Standard for Polymeric Materials - Use in Electrical Equipment Evaluations, evaluates polymeric materials intended for use in electrical equipment, focusing on environmental performance and durability. This includes assessments for environmental ratings such as F1 and F2, which indicate resistance to UV exposure and water immersion.

• Mechanical testing  
  Conducted alongside hot-air aging (RTI) and other conditioning methods like weathering simulations. These environmental tests combine real-world scenarios with accelerated aging techniques to help validate a material’s resistance, durability, safety and long-term performance in demanding conditions.
• Fabricated parts 
  UL 746D, the Standard for Polymeric Materials - Fabricated Parts, focuses on the evaluation of finished polymeric components.

Industrial laminates and printed wiring boards

UL 746E, the Standard for Polymeric Materials - Industrial Laminates, Filament Wound Tubing, Vulcanized Fibre, and Materials Used In Printed-Wiring Boards, covers standards for laminates, filament wound tubing, vulcanized fibre and materials used in printed wiring boards. It measures the ignition resistance of the conformal coating to electrical ignition sources. 

Flexible dielectric film materials

UL 746F, the Standard for Polymeric Materials - Flexible Dielectric Film Materials for Use in Printed-Wiring Boards and Flexible Materials Interconnect Constructions, applies to flexible materials such as polyimide used for insulation and conductivity in flexible circuits. 

Per- and polyfluoroalkyl substances (PFAS) and non-fluorinated materials

UL 746G, Outline of Investigation for Non-Fluorine and Non-PFAS Containing Materials, addresses the ongoing market demand for non-PFAS materials. It also defines the methodology for evaluating PFAS in virgin and recycled materials with a clear path of sample and test requirements based on the material type:

• Non-fluorine materials – Plastic materials recognized as non-fluorine contain ≤50 parts per million (ppm) of fluorine.
• Non-PFAS materials – Plastic materials recognized as non-PFAS contain ≤50 ppm of fluorine and <25 parts per billion (ppb) of specific PFAS content (listed in Table 8.2 of UL 746G) and ≤250 ppb of total specific PFAS content.
• Non-PFAS with total fluorine ≥50 mg/kg not due to polymeric PFAS – Plastic materials recognized as non-PFAS with total fluorine ≥50 mg/kg not due to polymeric PFAS contain ≤25 ppb of specific PFAS content (listed in Table 8.2 of UL 746G) and ≤250 ppb or total specific PFAS content, but has ≥50 ppm fluorine not due to polymeric PFAS. 
  (Note: A thorough and complete material formulation review is required to verify that the fluorine in the materials is not due to PFAS)

Restricted use substances

UL 746R, Outline of Investigation for Restricted Use Substances in Polymeric Materials, investigates the presence of restricted substances in polymeric materials, helping manufacturers evaluate compliance with global environmental and safety regulations, such as the Restriction of Hazardous Substances (RoHS) Directive for the EU.  

Our RoHS rating program includes ongoing inspections and testing throughout the life of the certification, confirming that certified products continue to meet RoHS requirements, including updates to substance restrictions. To demonstrate compliance with the latest regulations, the UL Solutions Yellow Card™ indicates materials that meet RoHS 2011/65/EU and 2015/863 standards. 

Non-halogenated polymeric materials

UL 746H, Outline of Investigation for Non-Halogenated Materials, covers the certification program for plastics (QMFZ2) that are non-halogenated and free from chlorine and bromine. It includes tests and certifies materials that meet these requirements.

This Outline of Investigation evaluates materials to two different rating schemes:

• Non-halogenated - Evaluates materials with respect to fluorine, chlorine and bromine content
• Non-chlorine and non-bromine - Evaluates materials with respect to chlorine and bromine

Certification provides easy and independent way for specifiers and other purchasers to search and find plastics.

Sustainable polymeric materials

UL 746S, the Standard for Evaluation of Sustainable Polymeric Materials for Use in Electrical Equipment, addresses the safety and performance of recycled plastics blended with virgin materials for use in electrical applications. Published on Aug. 30, 2023, this Standard reflects the industry's growing focus on sustainability.

UL Solutions tests mechanically recycled plastic compounds containing post-consumer or post-industrial content in accordance with UL 746S through our Component Certification program . Requirements for mechanically recycled plastic compounds have now been fully transitioned from UL 746D to UL 746S, aligning with evolving environmental goals and regulatory expectations. This shift supports manufacturers in developing safer, more sustainable products without compromising performance. 

Why material ratings matter

Material ratings show that a plastic has been tested and meets specific performance requirements — such as physical and flammability performance — under globally recognized standards and test methods.

Plastic materials with these ratings are listed in our UL Product iQ™ and ULTRUS™ Prospector® databases. This makes it easy to search and verify materials, giving you confidence that they meet globally recognized standards, test methods and certification requirements.

At UL Solutions, our experts can help you navigate product standards, certification processes and compliance challenges. With a strong local presence backed by a global network, we deliver knowledgeable, efficient service in your target markets — supporting manufacturers in protecting public safety and maintaining brand integrity.