This particular manufacturer used electric sheathed heating elements which fall under the domain of the UL 197 standard. Not only did they have to meet the new UL standard, they also served a global export market where their products were required to meet stringent import inspection standards for leakage current and resistance values. Ocean transport is an extremely humid environment that can compromise heater resistance values by moisture absorption. This results in elements having higher than desired leakage current values. Given these challenges, it was the goal of the manufacturer to exceed both the domestic UL and international import inspection requirements with the use of a single end seal specification that would accommodate both.

Join for free to read