23 Mar 2021

Electrical Safety and Performance Considerations

One of the key tools in combatting the COVID-19 pandemic will be vaccines.  They join flu shots, childhood immunizations, and vaccinations for some international travel in a growing list of medical vaccines, many of which need to be stored at certain temperatures. The temperature control requirements for vaccine storage equipment are generally more detailed and precise than those used for traditional residential or commercial refrigerating units. These differences, coupled with challenges faced by vaccine providers and administrators in selecting vaccine storage equipment led to the creation of NSF 456, which defines appropriate criteria for construction and performance of vaccine storge refrigerators, freezers, and combination units.

NSF 456 was drafted in late 2020 and is expected to go into effect in spring of 2021, most likely in April. It provides basic criteria to promote sanitation and protection of public health by preserving vaccines. The standard includes requirements for performance and safety, as well as labelling of vaccine storage units.  These include:

  • Temperature control requirements: When the unit door is open, probes in the unit must stay within a certain range, depending on the equipment type.  Refrigerators cannot go below 2°C or above 8°C, while freezers are allowed a range of -50°C to -15° C. After a 3-minute opening test, refrigerator temperatures need to recover to 5°C +/- 3° C and probes in freezers should not rise above -15° C.
  • Electrical Safety: To ensure refrigeration equipment meets applicable safety requirements, units must be assessed to existing electrical safety standards:
    • UL 60335-2-24 - Standard for Household Refrigeration Appliances.
    • UL 471 / UL 60335-2-89 - Standard for Commercial Refrigerators and Freezers.
    • IEC 61010-2-001 - Standard for Refrigerated Systems in Laboratory Equipment.
  • Sample requirements: A minimum of one unit per model must be tested, and family grouping will be vetted by engineering.
  • Labelling:  Units intended for the use and storage of vaccine must be labelled to indicate the usable interior space of the unit where the vaccine product may be stored. If the equipment contains a digital display, it is acceptable to utilize the display to indicate the overall storage capacity in lieu of physical labels. 
  • Certification: Units that are assessed and found to meet the requirements can be certified as having met the electrical safety and sanitation requirements.

Units are assessed for temperature control using vaccine simulation devices. The standard also includes guidance on how to construct and use the simulation devices in assessing the storage units. Manufacturers should be aware of the requirements while designing units and when sending them for assessment. Pretesting can help ensure the refrigerators and freezers will meet the criteria and can be certified and labelled, providing peace of mind to those administering vaccines on the front line. Learn more about the standard and our solutions by downloading our fact sheet.


Lee Moomaw,
Engineering Team Lead


Lee Moomaw is an Engineering Team Leader with 9 years of testing experience specific to sanitation and electrical product safety. He earned a BS degree in Biology and Chemistry from Heidelberg University and participates in various standard committees focusing on improving product sanitation requirements, including NSF and ASHRAE.

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