Data Bulletin: Date Code System

Current Date Code System (Implemented August 1996)

Merchandised distribution equipment and molded case circuit breakers are date coded to identify the time of manufacture. This code is useful for tracing equipment design changes and pinpointing assembly periods. The date code is placed separately or hand-stamped directly onto the device and should not be confused with label numbers or other identifying information.

IMPORTANT: Always obtain the date code when investigating a complaint on any device.

The current date code system uses the first two characters for the year of manufacture, the next two for the week of the year, and the fifth character for the day of the week (1=Monday, 7=Sunday). Previously, dual function circuit breakers had a sixth character ("H"), but this was dropped on January 1, 2017, reverting to a five-character code.

Code Structure Example: Year Week Day of week (e.g., 18 17 1)

Examples:

• PowerPact™ JG 250 Circuit Breaker: Date code 18071 indicates 2018, February 12, Monday.
• EHB14050EPD2100 Equipment Protection Device: Date code 03435 indicates 2003, October 24, Friday.
• PowerPact™ QBL32250 Circuit Breaker: Date code 09503 indicates 2009, December 8, Wednesday.
• Miniature Circuit Breaker HOM115CAFI: Date code 0825 indicates 2008, week 25 (June 16–22). No specific day of the week is listed.

Location of Date Code

Date codes can be found in the following areas of the equipment:

• QO and Homeline Circuit Breakers (arc and ground-fault only): Stamped on the device near the handle. Standard QO and Homeline use a two-letter date code stamped on the manifest label.
• QO™ Load Centers: Stamped on the wiring diagram or box label.
• Combination Entrance Service Devices: Stamped on the wiring diagram.
• Multi-metering Equipment: Stamped on the wiring diagram.
• Industrial Molded Case Circuit Breakers (including I-Line™): Included on the faceplate label on the front of the circuit breaker (since 1980).
• Enclosed Circuit Breakers: Found inside the cover or on the side of the box.
• Merchandised NQO, NQOB, QMB, and I-Line Panelboards: Stamped on the interior pan at the mains end.
• QMB Fusible Units: Stamped inside the cover.

Visual Examples of Date Code Locations:

• A molded case circuit breaker faceplate label, showing catalog number and other ratings. The date code is typically located below the catalog number.
• A molded case circuit breaker faceplate label, showing interrupting ratings. The date code is typically located below the interrupting ratings data.
• The inside cover of a Square D Safety Switch, displaying catalog number and other specifications. The date code is found here.
• The side of a circuit breaker, showing model number and ratings. The date code is stamped on the side.
• A molded case circuit breaker faceplate label, showing standard lug data. The date code is typically found below this data.
• The side of a circuit breaker, showing "MADE IN U.S.A." and catalog number. The date code is stamped on the side.

Legacy Date Code System (1956–1995)

This date code system was adopted in 1956 and was used on distribution equipment and circuit breakers until June 1994. High-volume QO™ circuit breakers were an exception. This system may still be encountered.

The code typically follows the format: Month Day of Month Year Operator Shift Number.

Month and Year Mapping:

Other Year Mappings:

Note: The letters "I", "O", and "Q" are not used in this date code system.

Variations:

• Month and year only (e.g., BA)
• Month, day, and year (e.g., B20A)
• Month, day, year, and shift (e.g., B20A2)

Important Notes:

• From 1951 through September 1965, codes for September-December were I, J, K, L.
• Day of the month could be one or two digits (e.g., 4 or 04).
• Letters I, O, Q, Y, Z were not used after September 30, 1965. The year code for 1965 was "O" until September and "S" thereafter.
• The date code system changed August 1, 1996.
• Specific plant variations exist (e.g., Pacifico Circuit Breakers Plant used "A" for Jan-Mar 2012 instead of "X").
• Peru plant used the first 6 months for specific coding.

Example: A Q12150 Circuit Breaker dated July 28, 1950, 1971, or 1992, Operator/Shift 1.

1950–1955 Date Code System

This method was used for date coding load centers, safety switches, and some circuit breakers manufactured in Detroit, MI, between 1950 and 1955.

The code format typically includes: Month Operator Year Number.

Month and Year Mapping:

Example: Circuit breaker dated June, 1955.

Pre-1950 Date Code System

Two methods were in use prior to 1950. The exact timing and location of use are not precisely determined, but can help establish a date of manufacture based on equipment appearance and service history.

Method 1: Month Year Operator Number

Example: Circuit Breaker dated January 22, 1934, Operator 22.

Method 2: Month Day of Year Operator Number

Example: ML1 Circuit Breaker dated either December 3, 1954, or January 23, 1954, Operator 720.