Kuinka laskea Circuit Breaker Sizing
Mikä on Circuit Breaker Sizing?
Selects appropriate circuit breaker to protect circuits from overcurrent while allowing normal operation. Wrong sizing causes nuisance trips or fire risk.
Kaava
Typical breaker = current × 1.25 (non-motor) or × 2.5 (motor)
Vaiheittainen opas
- 1Calculate circuit maximum current
- 2Breaker must exceed running current for motor inrush
- 3Typical breaker = current × 1.25 (non-motor) or × 2.5 (motor)
- 4Match breaker to wire ampacity (wire must handle breaker rating)
- 5Select trip curve (A, B, C, D) for application
Ratkaistut esimerkit
Syöte
40A circuit, #8 wire
Tulos
50A breaker
Yleisiä virheitä vältettäväksi
- ✕Oversizing breaker to avoid nuisance trips (creates fire hazard)
- ✕Using undersized wire for breaker rating
Usein kysytyt kysymykset
Why not just use larger breaker?
Oversized breaker won't protect from short circuits, creating fire/electrocution risk.
What's the difference between breaker curves?
A: sensitive (electronics), B: general, C: motors, D: high inrush; choose for application.
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