WEG UMBW Miniature Circuit Breakers – UL489 & UL1077 Listed


The WEG UMBW Series thermal-magnetic miniature circuit breakers deliver reliable protection for industrial electrical equipment. With UL489 and UL1077 approvals, the UMBW line provides versatile options for branch circuit and equipment protection, ranging from 1 to 63 amps with multiple pole configurations, accessories, and bus bar systems.

Key Points

  • Dual approvals: UL489 for branch circuit protection and UL1077 for equipment protection
  • Wide ampacity range from 1A to 63A for AC and DC applications
  • Positive trip-free snap action mechanism ensures reliable switching
  • Flexible bus bar connecting systems and terminals support easy installation
  • Available in 1, 2, and 3 pole configurations with B, C, and D trip curves
  • Compact 17.5mm width per pole with visual status indication
  • Multiple accessories offered, including auxiliary contacts, bell alarms, and shunt trips
  • Designed and manufactured by WEG, a global leader in electrical equipment solutions