What is the UL 60335-2-40 Standard?

First let’s start with what is ETL or Intertek listed and what is UL listed and what that means and what the difference is. ETL (Intertek) and UL (Underwriters Laboratories) are both Nationally Recognized Testing Laboratories (NRTLs) that certify products meet the same U.S. safety standards, meaning their certifications are functionally equivalent for consumers and retailers, though UL develops standards while ETL tests to existing ones (often UL’s). The primary differences are the certifying body, brand recognition (UL often stronger), and sometimes cost/speed for manufacturers, but for the end-user, both marks indicate a product has passed rigorous third-party safety testing.

UL 60335-2-40 is the rigorous safety benchmark specifically designed for electrical heat pumps, air conditioners, and dehumidifiers. Think of it as the modern “rulebook” that ensures HVACR equipment is engineered to be as safe as possible before it ever reaches a job site or home.

This standard focuses on neutralizing three primary risks:

  • Electrical Safety: Rigorous protection against electric shocks.
  • Fire Prevention: Strict guidelines to minimize combustion risks.
  • Mechanical Integrity: Ensuring moving parts and high-pressure systems don’t pose a physical threat.

Beyond the hardware itself, the standard mandates clear labeling and comprehensive user instructions, ensuring that the equipment is operated and maintained safely throughout its lifespan.

Why Testing and Compliance Matter

In the HVACR industry, safety isn’t just a preference—it’s a requirement. Manufacturers must put their products through exhaustive testing to prove they meet these high bars. When a unit carries a certification mark (like the ETL or UL listed marks), it serves as a “seal of approval” that the product has been vetted by third-party experts.

Key Advantages of Compliance:

  1. Risk Mitigation: The most critical benefit is the prevention of accidents. Testing ensures that systems can handle real-world stress without causing fires or injuries.
  2. Market Confidence: Compliance proves to engineers and facility managers that the equipment is reliable and built to the latest industry specifications.
  3. Future-Proofing: As refrigerants evolve (specifically the move toward A2L mildly flammable refrigerants), UL 60335-2-40 provides the necessary framework to handle these new materials safely.

Understanding the “Family” of Standards

UL 60335-2-40 is actually part of a larger global effort to harmonize safety standards. It is based on the International Electrotechnical Commission (IEC) standards. This “harmonization” makes it easier for manufacturers to design products that are safe for use both in the U.S. and internationally.

How to check to see if a manufacturer is ETL/UL Listed

Is the vendor your comparing Seasons 4 to ETL/UL Listed to the most current 60335-2-40 standard? You can search for vendors on the Intertek/ETL site to find out. Check here to see Intertek listings. UL Listings can be found here. If you think a vendor is not listed, simply ask them for their “Authorization to Mark” documents.

All Seasons 4 products are Intertek/UL listed. Here is a direct link to all the listings. The 60335-2-40 and the UL508A panels are the most current.