BK/ETF-1 Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The BK/ETF-1 is a 1 A, 277 V AC board mount fuse manufactured by Eaton - Electronics Division, designed for through-hole radial mounting in vertical orientation. This component is classified as obsolete, necessitating identification of active equivalent parts for new designs and ongoing production requirements. The fuse features slow-blow response characteristics and is approved by SEMKO and UL agencies. Due to its obsolete status, substitute parts with equivalent electrical and mechanical specifications are required for procurement and design continuity.

Substiute Parts

BK/ETF-1

Eaton - Electronics DivisionIn Stock: 764BK/ETF-1 Datasheet

Current PartRFQ

SR-5-1A-BK

Eaton - Electronics DivisionIn Stock: 999SR-5-1A-BK Datasheet

SimilarRFQ

0034.6615

SCHURTER Inc.In Stock: 1344840034.6615 Datasheet

SimilarRFQ

37211000411

Littelfuse Inc.In Stock: 194937211000411 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the BK/ETF-1 are identified based on the following critical parameters that determine functional equivalence:

Primary Matching Criteria:

• Current Rating: 1 A (exact match required)
• Response Time: Slow Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Fuse Type: Board Mount, Radial, Can, Vertical (exact match required)
• Package / Case: Radial, Can, Vertical (exact match required)

Secondary Compatibility Considerations:

• Voltage Rating - AC: The BK/ETF-1 operates at 277 V AC. Substitute parts rated at 250 V AC are compatible for applications where the circuit voltage does not exceed 250 V AC, as fuses must be rated equal to or greater than the circuit voltage.
• Breaking Capacity: The BK/ETF-1 specifies 100 A breaking capacity. Substitute parts with 35 A breaking capacity are suitable for circuits with lower fault current levels.
• Operating Temperature Range: The BK/ETF-1 operates from -55°C to 125°C. Substitute parts with narrower temperature ranges (-40°C to 85°C) are compatible for applications within those limits.
• Physical Dimensions: Minor dimensional variations (within manufacturing tolerances) are acceptable provided the radial, can, vertical package format is maintained.

Three substitute parts meet the core electrical and mechanical requirements:

1. SR-5-1A-BK (Eaton - Electronics Division): Active status, 1 A, 250 V AC, slow-blow, through-hole radial mount
2. 0034.6615 (SCHURTER Inc.): Active status, 1 A, 250 V AC / 125 V DC, slow-blow, through-hole radial mount
3. 37211000411 (Littelfuse Inc.): Active status, 1 A, 250 V AC, slow-blow, through-hole radial mount

Parameter Comparison

Engineering Selection Recommendations

Voltage Derating Consideration: The BK/ETF-1 is rated for 277 V AC operation. All three substitute parts are rated at 250 V AC maximum. Selection of substitute parts is appropriate only for applications where the circuit voltage does not exceed 250 V AC. For circuits operating at 277 V AC, the original BK/ETF-1 specification must be maintained, or alternative 277 V rated fuses must be sourced.

Breaking Capacity Assessment: The BK/ETF-1 specifies 100 A breaking capacity at rated voltage. Substitute parts SR-5-1A-BK and 37211000411 specify 35 A breaking capacity. The SCHURTER 0034.6615 specifies 35 A AC and 50 A DC breaking capacity. Selection of substitute parts with lower breaking capacity is appropriate only for circuits with maximum fault currents not exceeding the substitute part's breaking capacity rating.

Active Product Status: All three substitute parts carry Active product status, ensuring ongoing availability and manufacturing support. This contrasts with the BK/ETF-1 Obsolete status.

Compliance and Certification:

• SR-5-1A-BK: Approved by CCC, cULus, KC-MARK, PSE, SEMKO, VDE; ROHS3 Compliant
• 0034.6615: Approved by CCC, cURus, KC, PSE/JET, VDE; ROHS3 Compliant
• 37211000411: Approved by CCC, cURus, PSE, SEMKO, VDE; ROHS3 Compliant

All substitute parts maintain SEMKO approval (matching the original BK/ETF-1) and carry broader international certifications. All are ROHS3 compliant.

Temperature Range: The BK/ETF-1 operates from -55°C to 125°C. SR-5-1A-BK and 37211000411 operate from -40°C to 85°C, representing a narrower range. The SCHURTER 0034.6615 matches the full -55°C to 125°C range of the original part.

Recommended Selection Priority:

1. For applications requiring full -55°C to 125°C operation: 0034.6615 (SCHURTER)
2. For standard industrial applications (-40°C to 85°C): SR-5-1A-BK or 37211000411
3. For circuits with DC voltage requirements: 0034.6615 (rated 125 V DC)

Frequently Asked Questions (FAQ)

Q: Can I use a 250 V AC rated fuse in a 277 V AC circuit?

A: No. Fuses must be rated equal to or greater than the circuit voltage. A 250 V AC fuse is not suitable for a 277 V AC circuit. The BK/ETF-1 at 277 V AC rating is required for such applications. Substitute parts rated at 250 V AC are compatible only for circuits operating at 250 V AC or lower.

Q: What is the significance of the 100 A breaking capacity on the BK/ETF-1 compared to 35 A on the substitutes?

A: Breaking capacity indicates the maximum fault current the fuse can safely interrupt without rupturing or creating a hazard. The BK/ETF-1 can safely interrupt faults up to 100 A at 277 V AC. Substitute parts with 35 A breaking capacity are suitable only for circuits where the maximum available fault current does not exceed 35 A. For higher fault current circuits, the original BK/ETF-1 specification or alternative high-breaking-capacity fuses must be used.

Q: Are the physical dimensions of the substitute parts compatible with the BK/ETF-1 PCB footprint?

A: The BK/ETF-1 measures 0.329" Dia x 0.303" H (8.35mm x 7.70mm). Substitute parts measure approximately 0.335" Dia x 0.315-0.335" H (8.50mm x 8.00-8.50mm). These minor dimensional increases may require PCB layout verification to confirm adequate clearance and mounting hole compatibility. Physical testing or design review is necessary before production implementation.

Q: Which substitute part should I select for a new design?

A: Selection depends on circuit requirements. For circuits operating at 250 V AC or lower with fault currents not exceeding 35 A and temperatures between -40°C and 85°C, SR-5-1A-BK or 37211000411 are suitable. For circuits requiring the full -55°C to 125°C temperature range or DC voltage operation, select 0034.6615. Verify voltage, breaking capacity, and temperature requirements against your specific application before selection.

Q: What does "Slow Blow" response time mean?

A: Slow Blow fuses tolerate temporary current surges without opening, responding only to sustained overcurrent conditions. All substitute parts maintain this characteristic, ensuring compatibility with applications designed for the BK/ETF-1's slow-blow behavior.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All three substitute parts (SR-5-1A-BK, 0034.6615, and 37211000411) are ROHS3 compliant, meeting environmental and hazardous substance restrictions for modern electronics manufacturing.

Q: Can I use the SCHURTER 0034.6615 in both AC and DC circuits?

A: The 0034.6615 is rated for 250 V AC and 125 V DC operation, making it suitable for both AC and DC applications within these voltage limits. The other substitute parts (SR-5-1A-BK and 37211000411) are specified for AC operation; DC suitability is not documented.