Breaker trip curve

CertificationsOhio homeowner glossaryCC-BY-4.0

TL;DR

A breaker trip curve is the time-current characteristic graph showing how quickly a circuit breaker opens at each multiple of its rated current: slowly for mild overloads as the thermal element heats, and within milliseconds once current reaches the magnetic instantaneous range. Residential breakers follow one standard curve, but commercial and DC applications choose among designations like B, C, and D, which trip magnetically at roughly 3-5, 5-10, and 10-20 times rating.

Definition

What it means

A breaker trip curve is the time-current characteristic graph showing how quickly a circuit breaker opens at each multiple of its rated current: slowly for mild overloads as the thermal element heats, and within milliseconds once current reaches the magnetic instantaneous range. Residential breakers follow one standard curve, but commercial and DC applications choose among designations like B, C, and D, which trip magnetically at roughly 3-5, 5-10, and 10-20 times rating. Matching the curve to the load prevents nuisance trips from motor and compressor inrush without sacrificing fault protection. Electricians consult it when a properly sized breaker keeps tripping at equipment startup.

Category

Where it sits in the glossary

Breaker trip curve is part of the Certifications group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.

Why this matters for Ohio homeowners

Why Ohio homeowners should know it

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License: CC-BY-4.0 — quote freely with attribution to ProFix Editorial Team / ProFix Directory.

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