UL 840:2016 PDF Download

The UL 840:2016 standard for Insulation Coordination Including Clearances and Creepage Distances for Electrical Equipment provides an alternate approach to specifying the air and surface spacings for electrical equipment. It utilizes the principles of insulation coordination, which involves considering a combination of clearances, creepage distances, and the properties of solid insulation used in the insulation system.

This standard gathers empirical data to develop requirements for clearances and creepage distances, while a separate evaluation procedure for solid insulation is still being developed. These requirements can be used as an alternative to spacing levels specified in end-product standards, especially when the level of overvoltage control is unknown or not specified.

Manufacturers of electrical equipment can apply these requirements to a particular product category if the standard covering the product references UL 840 or any of its requirements. Users of this standard are expected to specify the overvoltage levels and methods of control they will be utilizing, as well as the pollution degree to which the product insulation system will be subjected.

It is important to note that the values specified in this standard are not intended for production line testing. However, users must establish a means to ensure that production controls for spacing reduction remain in effect during the manufacturing process. Factors not addressed in this standard, such as mechanical movement, field placement of conductive material, and product damage, should also be considered to ensure proper insulation coordination. Clearances and creepage distances at these locations must be verified for compliance through physical measurement.