MS 4.6 Board Mount Axial Fuse - Equivalent & Substitute Parts

Part Overview

The MS 4.6 is a board mount axial fuse manufactured by Bel Fuse Inc., rated for 4.6 A at 125 V AC/DC with slow blow response characteristics. This component is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing design support and production continuity. Equivalent parts must maintain identical electrical ratings, mechanical compatibility, and approval certifications to ensure direct board-level substitution without design modification.

Substiute Parts

MS 3.5

Bel Fuse Inc.In Stock: 858MS 3.5 Datasheet

Current PartRFQ

047103.5NRT1L

Littelfuse Inc.In Stock: 1139047103.5NRT1L Datasheet

SimilarRFQ

047303.5YRT1L

Littelfuse Inc.In Stock: 2411047303.5YRT1L Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the MS 4.6 are qualified based on the following mandatory electrical and mechanical parameters:

• Current Rating: 4.6 A (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (exact match required)
• Response Time: Slow Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Fuse Type: Board Mount, Axial configuration (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (minimum requirement)

Both substitute parts listed below meet these core substitution criteria. Physical dimensions vary within acceptable through-hole board mount tolerances. Approval agency certifications differ but do not preclude substitution in applications where the substitute certifications are acceptable.

Parameter Comparison

Engineering Selection Recommendations

Both Littelfuse PICO® II series fuses (047104.6NRT1L and 047304.6YRT1L) are active production alternatives to the obsolete MS 4.6. Selection between these two substitutes should be based on the following factors:

047104.6NRT1L is suitable for applications where PSE and UR certifications satisfy regulatory requirements. This part features a smaller diameter (0.110") compared to the original MS 4.6 (0.125"), which may provide board layout advantages in space-constrained designs.

047304.6YRT1L is suitable for applications requiring CSA certification in addition to PSE and UR approvals. This part features a diameter (0.135") slightly larger than the original MS 4.6 (0.125"), and provides a lower DC cold resistance (0.024 Ohms versus 0.046 Ohms), which may be beneficial in low-impedance circuit applications.

Both substitutes maintain identical electrical performance at the specified 4.6 A, 125 V AC/DC rating with slow blow response. Physical dimension variations are within acceptable tolerances for through-hole axial fuse board mounting. Approval agency differences do not affect electrical substitutability; selection should align with application-specific compliance requirements.

Frequently Asked Questions (FAQ)

Q: Can the 047104.6NRT1L or 047304.6YRT1L be used as direct replacements for the MS 4.6 without board redesign?

A: Yes. Both substitute parts maintain identical current rating (4.6 A), voltage rating (125 V AC/DC), response time (slow blow), and through-hole axial mounting configuration. Physical dimensions vary slightly but remain compatible with standard axial fuse board mount footprints. No circuit design changes are required.

Q: What is the difference between the two Littelfuse substitutes?

A: The primary differences are diameter (047104.6NRT1L: 0.110", 047304.6YRT1L: 0.135"), DC cold resistance (047104.6NRT1L: not specified, 047304.6YRT1L: 0.024 Ohms), melting I²t value (047104.6NRT1L: not specified, 047304.6YRT1L: 26.8), and approval certifications (047104.6NRT1L: PSE/UR, 047304.6YRT1L: CSA/PSE/UR). Electrical performance at rated current and voltage is identical.

Q: Are there any compliance or certification concerns when substituting these parts?

A: The MS 4.6 carries CE, CSA, and cURus certifications. The 047304.6YRT1L includes CSA certification, matching the original. The 047104.6NRT1L does not include CSA or CE certification. Verify that substitute certifications align with your application's regulatory requirements before implementation.

Q: What is the impact of the diameter difference on board layout?

A: The 047104.6NRT1L (0.110" diameter) is smaller than the original MS 4.6 (0.125" diameter), potentially allowing tighter board spacing. The 047304.6YRT1L (0.135" diameter) is slightly larger. Both remain within standard through-hole axial fuse mounting tolerances. Verify hole diameter and pad spacing on your PCB to confirm compatibility.

Q: Can I mix MS 4.6 and substitute parts in the same production run?

A: No. For production consistency and traceability, use a single part number per design revision. Select either the MS 4.6 (if available from inventory) or one of the two Littelfuse substitutes, and maintain that selection throughout the production lot.