UL and ETL are both what is called Nationally Recognized Testing Laboratories (NRTL). NRTLs are in place to provide independent safety and quality certifications on products. Electrical appliances typically require their certification (especially 240V appliances). UL develops the testing standards and tests to them. ETL tests to UL standards. In order for an inspector to sign off on permitted installation for an EVSE, the National Electric Code requires the EVSE be NRTL listed (in the US that is ETL or UL).

 A two-digit number established by the International Electro Technical Commission, is used to provide an Ingress Protection rating to a piece of electronic equipment or to an enclosure for electronic equipment. The first digit indicates protection against ingress of solid objects. The second digit indicates protection against ingress of liquids. For more details on the protection level of each digit, please refer to this page.