ElectraKit
Electrical fundamentals

Standard Overcurrent Device Rating Calculator

Find the next standard ampere rating listed for a fuse or fixed-trip circuit breaker.

Overcurrent protection reference

Current and device type

A

Enter the value that must be compared with a standard device rating.

Common reference values:
Standard rating lookup
20A
Entered value18 A
Lookup resultNext listed rating
Circuit breaker rating
10 A
15 A
20 A
25 A
30 A
35 A
40 A
45 A
50 A
60 A
70 A
80 A
90 A
100 A
110 A
125 A
150 A
175 A
200 A
225 A
250 A
300 A
350 A
400 A
450 A
500 A
600 A
700 A
800 A
1000 A
1200 A
1600 A
2000 A
2500 A
3000 A
4000 A
5000 A
6000 A
Reference onlyThis lookup does not select or approve an overcurrent device. Check calculated load, conductor protection, equipment markings, interrupting rating, and all application-specific rules.

About this calculator

Enter a current value and select a circuit breaker or fuse. The lookup highlights the first listed standard rating that is equal to or greater than the entered value.

This is a standard-rating reference only. It does not select a fuse or breaker for an installation.

Method and assumptions

The list follows the standard ampere ratings in NEC Table 240.6(A). Fuse-only ratings are shown only when Fuse is selected. Values outside the listed range are not extrapolated.

Use the result only after the applicable load, conductor, equipment, and protection requirements have been determined.

FAQs

Does the lookup recommend a breaker or fuse?

No. It identifies a standard rating at or above the value you enter. It does not determine the required device rating or confirm that the device is suitable for the circuit.

Why are there fuse-only ratings?

Table 240.6(A) includes a few additional standard ratings for fuses. They are not included in the circuit-breaker list.

Can the next standard rating always be used?

No. Load calculations, conductor protection, equipment markings, interrupting ratings, and application-specific requirements determine whether a device rating is permitted.

Related tools

Motor Full-Load Current and Circuit Protection ReferenceLook up motor-specific branch protection limits.Branch Circuit Conductor and Breaker CheckCompare general branch-circuit load and conductor ampacity.Conductor Ampacity CalculatorApply conductor temperature and current-count corrections.

Sources