Miniature Circuit Breaker
UL 1077

Product Description

• UL 1077 devices are only acceptable for providing supplementary protection where there is branch circuit protection ahead of it.

UL 1077 Supplementary Protectors & Overcurrent Devices

UL 1077 Supplementary Protector is a manually resettable device designed to open the circuit automatically on a predetermined value of time versus current or voltage within an appliance or other electrical equipment. A supplementary protective device is intended to provide limited overcurrent protection for specific applications and utilization equipment such as cabinet lighting and appliances.

UL 1077 Applications:

• Cabinet Lighting
• Appliances
• Control Power Transformers
• Relays
• Control Circuits

UL 489 products have larger dimensions to provide the necessary phase to phase voltage air gap.


• DIN rail mountable
• Field mounted accessories
• Various levels of protection (curves

Miniature circuit breakers have different protection curves to accommodate different applications

C Curve

In Type C curve applications, the magnetic trip is set between 5-10 times the full load current. This is the most common protection used for cables, lighting, resistive loads, general purpose applications and when properly sized, for motors.

D Curve

Type D curve applications have a higher setting of 7-15 times the full load current due to the inrush current of motor loads and the magnetizing current on the primary of a transformer or solenoid. Application for this curve include motor loads, transformer primary and solenoids due to the inrush or magnetizing currents.

B Curve

Type B curves provide a magnetic trip setting of 3-5 times the full load current. Applications: electronic circuits.

UL 1077 Product Overview

The B1E UL 1077 miniature circuit breaker has a complete range of amperages from 1A to 125A. Standard ratings of 5 kA at 480Y/277 Vac and 10 kA at 240 Vac. These are suitable for supplementary protection.

• Breakers mount on standard 35 mm DIN rail
• Thermal-magnetic over current protection – three levels of protection, categorized by B, C and D curves

• Fulfills UL 1077, IEC 60947-2 standard
• Field-installable shunt trip and auxiliary switch up to 63A
• Module width of only 0.71 in (18 mm) per pole
• Contact position indicator (red/green)
• 5-Year limited warranty


UL 1077 No. E355391 / IEC 60947-2

• Supplementary Protectors are UL Recognized for use in the United States in accordance with NFPA® 70 (NEC).

• These devices comply with UL 1077 No. E355391 and UL recognized for Canada CSA standards 22.2 No. 5 meeting the requirements for supplementary protectors.

• These devices are for international and domestic use, and also comply with IEC 60947-2 and are CE marked.

Typical Applications

• Supplementary protection control circuits
• Cabinet lighting
• Appliances

UL 1077 Accessories

Shunt Trip
Under-Voltage Trip
Alarm Switch
Auxiliary Contact