How to Read a Circuit Breaker Catalog Number (Square D, Eaton, Siemens, GE)

Published: 2025-06-04 | 8 min read | Category: Technical Guide

A circuit breaker catalog number is a coded string that tells you the brand, frame size, amperage, number of poles, voltage rating, and trip type — all in one compact identifier. For example, Square D "HJA36100" decodes as: H-frame (H), J-class interrupting rating (J), standard thermal-magnetic trip (A), 3-pole (3), 600V (6), 100 amps (100). Once you understand the pattern, you can identify any breaker's specifications from its catalog number alone.

Each manufacturer uses a different coding system, but they all encode the same core information: frame/series, poles, voltage, amperage, and trip type. The catalog number is printed on every breaker's label and is the single most important piece of information when ordering a replacement — it guarantees you get an exact match.

Square D Catalog Number Format

Square D uses a consistent letter-number system across all their breaker lines. The format is: [Frame][Interrupting Class][Trip Type][Poles][Voltage Code][Amperage].

| Position | Meaning | Example Values | |---|---|---| | 1st letter | Frame size | H=H-frame, J=J-frame, L=L-frame, M=M-frame, P=P-frame | | 2nd letter | Interrupting class | D=standard, G=high, J=extra-high, L=very-high | | 3rd letter | Trip type | A=thermal-magnetic, P=electronic | | 1st digit | Number of poles | 2=two-pole, 3=three-pole | | 2nd digit | Voltage code | 2=240V, 4=480V, 6=600V | | Remaining digits | Amperage | 015=15A, 100=100A, 400=400A |

**Key takeaway:** "HJA36100" = H-frame, J-class (65kAIC), thermal-magnetic trip, 3-pole, 600V, 100A. Knowing this code lets you verify you're ordering the exact right breaker without guessing.

**Example decodes:** - **QO120** = QO series, 1-pole, 20A (residential) - **EDB34030** = E-frame, D-class, B-trip, 3-pole, 480V, 30A - **HGA36150** = H-frame, G-class (100kAIC), A-trip, 3-pole, 600V, 150A

Eaton Catalog Number Format

Eaton uses a similar but distinct system. Their residential lines (BR, CH) use simple formats, while industrial lines (FD, HFD, JD) follow a frame-class-poles-voltage-amperage pattern.

| Series | Format | Example | |---|---|---| | BR (residential) | BR + [poles][amps] | BR230 = 2-pole, 30A | | CH (residential) | CH + [poles][amps] | CH120 = 1-pole, 20A | | FD (industrial) | FD + [poles][voltage code][amps] | FD3100 = 3-pole, 100A | | HFD (high-interrupt) | HFD + [poles][voltage code][amps] | HFD3060 = 3-pole, 60A |

**Key takeaway:** Eaton's residential numbers are the simplest to read — "BR230" is immediately obvious as a 2-pole 30-amp BR-series breaker. Their industrial numbers follow the same poles-voltage-amps pattern as Square D.

Siemens Catalog Number Format

Siemens uses letter prefixes to indicate frame size and interrupting capacity, followed by poles, voltage code, and amperage.

| Prefix | Frame | Interrupting Capacity | |---|---|---| | BQ | B-frame | 10kAIC (residential) | | ED | E-frame | 18-25kAIC | | FD | F-frame | 25-35kAIC | | HFD | F-frame | 42-65kAIC | | JD | J-frame | 25-35kAIC | | ND | N-frame | 50kAIC |

**Example:** "HFD63F250" = H-interrupting, F-frame, 6=600V, 3-pole, F=fixed thermal-magnetic, 250A.

GE Catalog Number Format

GE's residential THQL series uses a straightforward format: THQL + [poles] + [amps]. Their industrial TED/THED/TFK series follows the industry-standard frame-poles-voltage-amps pattern.

| Series | Example | Decode | |---|---|---| | THQL | THQL1120 | 1-pole, 120V, 20A | | THQL | THQL2150 | 2-pole, 150A | | TED | TED134030 | T-frame, E-class, D-trip, 3-pole, 480V, 30A |

How to Use the Catalog Number When Ordering

The catalog number is your guarantee of getting an exact replacement. When ordering from AllBreakerSales.com, search by the complete catalog number printed on your existing breaker's label. If the label is worn or illegible, our Cross-Reference Finder can identify the part from partial information, and our team at **(877) 611-0034** can help decode any catalog number from any manufacturer.

Frequently Asked Questions

What does the number in a circuit breaker catalog number mean?

In most catalog numbers, the number represents the amperage rating. For example, in Square D HFD36100, the '100' is 100 amps. In Eaton EDB3100, the '100' is also 100 amps. In Siemens HFD62F040, the '040' is 40 amps.

What does the pole count mean in a catalog number?

The pole count tells you how many conductors the breaker protects. '1' or '1P' is single-pole (one hot wire, used for 120V circuits). '2' or '2P' is double-pole (two hot wires, used for 240V circuits). '3' or '3P' is three-pole (three hot wires, used for 3-phase 208V or 480V circuits).

How do I find the catalog number on an existing breaker?

The catalog number is printed on the breaker's label, usually on the front face or side. On older breakers, it may be stamped into the case. If the label is worn, look for the frame designation (like 'HFD' or 'EDB') and the amperage rating, which together can identify the part.