Protect Industrial Circuits with the Right IMO Circuit Breaker

UL 489 BRANCH CIRCUIT PROTECTION

Protect Industrial Circuits with the Right IMO Circuit Breaker

Select an IMO Precision Controls miniature circuit breaker by trip curve, pole count, and rated current. Available configurations cover 0.5A to 63A, 1 to 3 poles, and 10kA short-circuit breaking capacity.

Shop IMO Circuit Breakers Use the Selection Guide
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10kABreaking capacity
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UL 489Branch circuit approval
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0.5–63AAvailable rated current
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17.5mmWidth per pole

⚙️ What Does an IMO Miniature Circuit Breaker Do?

An IMO Precision Controls miniature circuit breaker protects branch-circuit wiring and equipment from sustained overloads and short circuits. Its thermal element responds to overload current, while its magnetic element trips rapidly during a high-current fault. A resettable DIN-rail design makes it practical for control panels, OEM machinery, and electrical distribution equipment.

Thermal responseTrips on sustained overloads that can overheat conductors and connected equipment.
Magnetic responseTrips quickly when short-circuit current rises into the breaker's instantaneous range.
Visible statusA contact-position indicator supports faster inspection and troubleshooting.

📈 Choose the Correct Trip Curve

The trip curve determines how much temporary inrush current the breaker tolerates before instantaneous magnetic tripping. Choose the curve from the actual startup profile of the load, not from amperage alone.

B CurveInstantaneous trip: 3–5 × rated current (In)

Best fit: low-inrush loads.

  • Resistive loads
  • Heaters
  • Lighting with low startup current
  • Sensitive control circuits

Choose B when fast magnetic response is needed and startup current is limited.

C CurveInstantaneous trip: 5–10 × rated current (In)

Best fit: moderate-inrush loads.

  • Control transformers
  • Relays and contactors
  • Solenoids
  • Small motor circuits

Choose C for many general industrial control and automation loads.

D CurveInstantaneous trip: 10–20 × rated current (In)

Best fit: high-inrush loads.

  • Motors
  • Larger transformers
  • Inductive equipment
  • High-startup machinery

Choose D only when measured or documented inrush justifies the wider trip range.

Avoid nuisance-trip guesswork: Do not move to a slower curve or larger amp rating until conductor ampacity, equipment protection requirements, available fault current, and manufacturer instructions have been verified.

🔌 Match Pole Count and Current Rating

Pole count determines how many conductors are opened together. Rated current must protect the installed conductors and meet the load and equipment requirements. The configurations below reflect the IMO models covered by this page.

1 Pole 17.5mm wide

Use where one protected conductor must be interrupted.

B: 10A, 15A, 60A
C: 0.5A, 1A, 1.6A, 2–8A, 10A, 13A, 16A, 20A, 25A, 30A, 32A, 40A, 50A, 60A, 63A
D: 2A, 3A, 7A, 8A, 16A, 30A, 63A
2 Pole 35mm wide

Use for linked protection and disconnection of two circuit conductors.

B: 20A, 60A
C: 0.5A, 1A, 1.6A, 2A, 4–8A, 10A, 13A, 15A, 16A, 20A, 25A, 30A, 32A, 40A, 50A
D: 2A, 32A, 63A
3 Pole 52.5mm wide

Use for linked interruption across three-phase circuit conductors.

B: 6A, 60A
C: 1.6A, 2A, 5A, 6A, 10A, 15A, 16A, 32A, 50A
D: 1A, 10A, 25A

Example IMO circuit breakers

UB10B1010A10A · B curve · 1 pole UB10C2016A16A · C curve · 2 pole UB10D3010A10A · D curve · 3 pole

📋 IMO Technical Quick Reference

Use these common specifications for initial comparison, then confirm on the selected product page for your project requirements before ordering.

Protection methodThermal-magnetic overcurrent protection
Breaking capacity10kA
Voltage, 1 pole277VAC / 48VDC
Voltage, 2 pole480Y/277VAC / 96VDC
Voltage, 3 pole480Y/277VAC
Frequency50/60Hz
Operating temperature-13°F to 131°F (-25°C to 55°C)
Calibration temperature104°F (40°C)
Terminal wire range18–3 AWG
Fastening torque2.5Nm (22.2lb-in)
Service life20,000 mechanical / 6,000 electrical operations
Enclosure protectionNEMA 1 / IP20
MountingDIN rail
ComplianceUL 489, IEC 60947-2, IEC 60898-1, RoHS

Overall height and depth are approximately 108mm × 67mm. Width increases by pole count: 17.5mm, 35mm or 52.5mm.

How to read an IMO UB10 part number

UB10 C 2 016 A
UB10
Product family
C
Trip curve
2
Pole count
016A
16A current code

Examples: UB10C100.5A is 0.5A, C curve, 1 pole; UB10D3025A is 25A, D curve, 3 pole.

✅ 5-Step Circuit Breaker Selection Checklist

Work through these checks before choosing a model. Final sizing and installation should be completed by qualified personnel in accordance with applicable codes.

1. Verify voltageConfirm AC/DC rating and system configuration.
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2. Size the currentProtect the conductor and meet load requirements.
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3. Match polesSelect 1, 2 or 3 linked poles for the circuit.
4. Check inrushUse load data to select B, C or D curve.
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5. Confirm fault ratingAvailable fault current must not exceed the breaker's rating.

Frequently Asked Questions

Are IMO UB10 breakers suitable for branch circuits?Yes. The models covered here are UL 489 approved for qualifying branch-circuit protection applications.
What is the difference between B, C and D curve breakers?B, C and D curves have instantaneous magnetic trip ranges of 3–5, 5–10 and 10–20 times rated current, respectively. Higher-letter curves tolerate more startup current before magnetic tripping.
Can a larger breaker stop nuisance tripping?It may hide the symptom while leaving conductors or equipment improperly protected. Verify the load's inrush, breaker curve, conductor ampacity and equipment instructions before changing the rating.

Ready to Select an IMO Circuit Breaker?

Filter the available IMO circuit breakers by current, trip curve, and pole count to find the configuration that matches your control panel or distribution system.

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Safety note: Circuit breaker selection and installation must account for conductor ampacity, equipment requirements, voltage, available fault current, ambient conditions, and applicable electrical codes. Installation should be performed by qualified personnel.