An EIS is composed of a unique combination of materials that have been verified for chemical compatibility when used at certain maximum temperatures. These combinations are arranged to form insulation systems such as those used in motors, transformers and solenoids.

Systems at 600 volts or less are recognized by UL for use above Class 105(A) limits. These systems have been tested in accordance with UL 1446, Standard for Safety of Systems of Insulating Materials — General. UL 1446 also serves as the model for the following international standards:


Standard  Title
IEC 62114 Electrical Insulation Systems — Thermal Classification
IEC 60505 Evaluation and Qualification of Electrical Insulation
IEC 61857 Electrical Insulation Systems — Procedures Part 1: General Requirements-Low Voltage
IEC I61857-21 Electrical Insulation Systems — Procedures Part 21: Specific Requirements for General Purpose Model-Wire Wound Applications
IEC 61858 Electrical Insulation Systems — Thermal Evaluation of Modification to an Established Wire-Wound EIS

UL groups Recognized systems into two product categories identified by the alphanumeric category control numbers (CCNs) below:

  • Systems, Electrical Insulation (OBJY2) – Applies to insulation systems that are evaluated after being built around supplier components. The UL Recognized EIS is available for coil manufacturers’ use.
  • System Components, Electrical Insulation (OBJS2) – Applies to UL Recognized insulation systems used in facilities where coil is produced. These systems are evaluated for coil manufacturers or adopted from an OBJS2 supplier. Components available for adoption by coil manufacturers can be quickly identified in UL’s online EIS database, UL iQ™ for Electrical Insulation Systems.