UL 50E- Elastomers to Electrical Equipment Enclosure requirements

UL 50E Compression Test applies only to cellular gasket materials used in Periodic Recompression applications where the seal may periodically be broken and must be reestablished, such as around doors or covers of electrical enclosures.  Solid gasket materials and cellular gasket materials used in electrical enclosures where the seal is intended to be under continuous compression for the life of their use, such as gaskets used in pilot lights, selector switches and viewing windows, are not required to comply with the UL 50E Compression Test.

UL certifies gaskets to UL 50E requirements with these ratings:

• “UL 50E” refers to solid gaskets that need not comply with the Compression Test.  They are considered suitable for either Continuous Compression or Periodic Recompression applications.
  
• “UL 50E Continuous Compression” refers to cellular gaskets that have not been evaluated to the Compression test requirements.  They are considered suitable only for Continuous Compression applications.
  
• “UL 50E Periodic Recompression” refers to cellular gaskets that comply with the Compression Test requirements. They are considered suitable for either Continuous Compression or Periodic Recompression applications.

The basic standard used to evaluate elastomeric gasket materials is UL Standard 157 “Gaskets and Seals.”  In addition to certifying gaskets materials to UL 157,  UL offers Component Recognition for UL 50E and a wide range of other UL end-product applications. 

UL's extensive certification program for elastomeric materials facilitates the acceptance of these components in a customer’s end-products.
The first edition of UL 50E, the Standard for Enclosures for Electrical Equipment, Environmental Considerations, incorporates a new “Compression Test” in addition to the tensile strength, elongation and volume change requirements previously in effect.  The effective date of September 4, 2012 originally set for compliance with the new Compression Test recently was extended to September 4, 2015 to permit additional time for gasket manufacturers and their customers to attain certification with respect to the new requirement.