Siemens 5SJ4218-8HG42 Miniature Circuit Breaker
Product Family Context
The 5SJ4 series denotes Siemens' line of DIN-rail-mounted miniature circuit breakers (MCBs) intended for branch-circuit protection in industrial and commercial installations. The 5SJ prefix identifies the product family; the numeric blocks encode the voltage class, current rating, and breaking characteristic. Devices in this series target single-phase and multi-phase distribution where listed protection against overload and short-circuit is required.
Catalog-Level Parameters
| Parameter | Value |
|---|---|
| Brand | Siemens |
| Series | 5SJ4 |
| Current Rating | 15 A |
| Voltage Class | 480/277 V AC |
| Number of Poles | 2 |
| Mounting | DIN Rail |
| Actuator | Lever |
| Illumination | None |
| Package | Bulk |
| Product Status | Active |
| RoHS Compliance | Non-compliant |
Approval Coverage (On Record)
The following agency listings are indexed in the catalog entry for this MPN: CCC, CE, CSA, EAC, UL, VDE. Approval scope is determined by the listing agencies and the specific end-use conditions; the catalog does not break down which ratings apply to which standard revision or test condition.
Physical Construction Notes
The unit uses a lever-type actuator. Illumination is not included. The device ships in bulk packaging. These attributes reflect a standard panel-mount configuration without integral status indication.
In-Catalog Comparison Rows (Not OEM-Approved Substitutes)
The catalog lists several 5SJ4 family members with matching pole count, voltage class, and mounting. All require the engineer's own qualification against the specific application requirements before substitution. The table below shows shared spec keys for the top similarity rows.
| MPN | Current Rating | Voltage | Poles | Mount | Package |
|---|---|---|---|---|---|
| 5SJ4218-8HG42 (primary) | 15 A | 480/277 V | 2 | DIN Rail | Bulk |
| 5SJ42188HG41 | 15 A | 240 V | 2 | DIN Rail | Bulk |
| 5SJ4218-7HG42 | 15 A | 480/277 V | 2 | DIN Rail | Bulk |
Why 5SJ42188HG41 is Catalog-Similar
Matches the primary part in current rating (15 A), pole count (2), mounting (DIN Rail), and actuator type. The voltage class differs: 240 V versus the seed's 480/277 V. The breaking characteristic suffix differs (D-TRIP). Bulk package matches.
Why 5SJ4218-7HG42 is Catalog-Similar
Matches the primary part in current rating (15 A), voltage class (480/277 V), pole count (2), and mounting (DIN Rail). The breaking characteristic differs: C-TR versus D-TR. Bulk package matches. The approval agency list in the catalog entry also diverges (C-TR variant omits CSA from the listed set).
Selection Considerations for 5SJ4 Series DIN-Rail MCBs
- Voltage coordination: Devices rated 480/277 V AC suit multi-wire branch circuits in three-phase Wye systems. Devices rated 240 V AC target single-phase or split-phase applications. Voltage class must align with the protected circuit topology.
- Current rating: The 15 A rating in this row is fixed. Adjacent catalog rows span 5 A through 16 A in the 480/277 V class. Load ampacity determines the rating selection.
- Breaking characteristic (trip curve): D-TR and C-TR designate different instantaneous trip bands. D curve provides higher magnetic pickup; C curve is more sensitive. The appropriate curve depends on the inrush characteristics of the protected load.
- Agency approvals: Not all listed agencies cover all voltage or current ratings within a series. The catalog lists agencies per MPN; specific test conditions and applicable standards require end-use verification.
- Package type: Bulk packaging (as indexed for this MPN) versus box packaging in alternate rows. Quantity-per-pack affects ordering logistics for panel builds.