Technical Selection Guide – Circuit Breaker

1. Define Circuit Load Requirements

Determine the maximum continuous current of all loads connected to the circuit. Use device nameplate ratings or system design current, not nominal values.

Example:

• 12V Refrigerator: 10A

• Auxiliary Lighting: 5A

• Total Continuous Load: 15A

2. Apply Engineering Safety Factor

Select a circuit breaker rated at 125%–150% of the continuous load to accommodate current fluctuations and prevent nuisance tripping.

• Selection Formula: Breaker Rating = Continuous Load × 1.25–1.5

• Example: 15A × 1.25 = 20A recommended breaker

3. Select Appropriate Breaker Characteristics

Choose breaker type based on system behavior:

● Manual Reset

Preferred for OEM and retrofit vehicle systems

Allows clear fault identification and controlled reset

● Auto Reset

Suitable for non-critical or intermittent loads

Not recommended where fault diagnosis is required

4. Verify Rated Voltage Compatibility

Breaker voltage rating must meet or exceed system voltage.

• 12V DC electrical system → 12V DC rated breaker

• 24V DC electrical system → 24V DC rated breaker

Underrated voltage may result in unsafe operation or failure. Voltage Rating does not exceed 48V

5. Evaluate Installation & Operating Conditions

For different applications, ensure the breaker meets environmental requirements:

• Vibration resistance (vehicle-grade design)

• Ingress protection (IP65 or higher recommended)

• Accessible mounting location for inspection and reset

6. Avoid Over- or Under-Specification

Undersized breakers may cause repeated tripping

Oversized breakers may fail to provide adequate circuit protection

Select the lowest breaker rating that safely exceeds operating current.

Selection Summary

• Identify continuous load current

• Apply 125%–150% design margin

• Match breaker type to load behavior

• Confirm voltage rating

• Validate environmental suitability