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Circuit Breaker Candidate Calculator

Compare actual breaker catalog ratings with weighted circuit current and verified conductor or equipment limits; identify when no candidate fits.

Use this result well

Inputs that matter
Circuit and protection basis, Noncontinuous load (A), Continuous load (A), Continuous-load factor, and 3 more
Output to expect
Breaker candidate selection
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Breaker candidate selection

Find the lowest entered, available breaker rating that meets a noncontinuous plus weighted continuous load without exceeding the verified protection ceiling. Use a separately established ceiling for conductor protection and equipment. Motors and other special-load rules require their own design.

Required amperes = noncontinuous A + continuous A × chosen factor; candidate must be at least required A and at most protection ceiling A.

Updated: September 2026

Example Scenarios

Try the built-in example, then replace its source data with your actual documented values. Retain failed comparisons and unresolved decisions.

→ 25 A catalog candidate

FAQ

Find the lowest entered, available breaker rating that meets a noncontinuous plus weighted continuous load without exceeding the verified protection ceiling. Use a separately established ceiling for conductor protection and equipment. Motors and other special-load rules require their own design.

Use the exact equipment, dimensions, current ratings, operating conditions and applicable requirements described in the selected mode. Unknown values are not replaced by a generic wire, device count or capacity. Illustrative examples are arithmetic examples, not an approved installation.

Save planning case keeps an explicit local history entry. Copy MD retains current inputs, source notes and interpretation; Download CSV exports the current result breakdown. Export a separate copy before changing devices or clearing browser storage.

About Circuit Breaker Candidate Calculator

Find the lowest entered, available breaker rating that meets a noncontinuous plus weighted continuous load without exceeding the verified protection ceiling. Use a separately established ceiling for conductor protection and equipment. Motors and other special-load rules require their own design.