Understanding How to Apply UL 489 and UL 1077 Devices Do you know the differences between UL 489 and UL 1077? The key to understanding UL 1077 supplementary protection and UL 489 branch protection requirements is to first understand how to identify the products, the applications they can be used for and importance of selecting the correct device in compliance with UL standards. While both types of protection are useful and have similar purposes, each [...]