Equivalent & Substitute Parts for BK/GDC-125MA Glass Fuse Cartridge

Part Overview

The BK/GDC-125MA is a 125 mA, 250 V AC/DC slow-blow glass fuse cartridge in 5mm x 20mm form factor, manufactured by Eaton - Electronics Division. This component is classified as Active product status and requires a compatible fuse holder for installation. Equivalent and substitute parts are identified based on matching electrical ratings, mechanical dimensions, response characteristics, and approval certifications to ensure direct functional interchangeability in circuit protection applications.

Key Parameters

Parameter	Value
Current Rating	125 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	5mm x 20mm
Breaking Capacity @ Rated Voltage	35A
Mounting Type	Requires Holder
RoHS Status	RoHS Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the BK/GDC-125MA is determined by strict equivalence across the following critical parameters:

Primary Matching Criteria:

Current Rating: 125 mA (exact match required)
Voltage Rating: 250 V AC (exact match required)
Response Time: Slow Blow (exact match required)
Package Dimensions: 5mm x 20mm (exact match required)
Breaking Capacity: 35A (exact match required)
Fuse Type: Cartridge, Glass (exact match required)

Secondary Compatibility Factors:

Mounting Type: Requires Holder (all substitutes use same holder interface)
Approval Agencies: Must include at least one common certification body
RoHS Compliance: ROHS3 Compliant or RoHS Compliant status

Parts are grouped into two categories: Direct Manufacturer Equivalents (same manufacturer, different series) and Cross-Manufacturer Parametric Equivalents (different manufacturers with identical electrical and mechanical specifications).

Parameter Comparison

Part Number	Manufacturer	Series	Current (mA)	Voltage (V AC)	Response	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ω)	Approval Agencies	RoHS Status
BK/GDC-125MA	Eaton	GDC	125	250	Slow Blow	5x20mm	35	0.063	1.97	cULus, IMQ	RoHS Compliant
BK/S506-125-R	Eaton	S506	125	250	Slow Blow	5x20mm	35	0.063	1.97	BSI, CCC, CSA, IMQ, SEMKO, UR, VDE	ROHS3 Compliant
BK/GMD-125-R	Eaton	GMD	125	250	Slow Blow	5x20mm	35	0.043	8.125	CSA, UL	ROHS3 Compliant
BK1/S506-125-R	Eaton	S506	125	250	Slow Blow	5x20mm	35	0.063	1.97	BSI, CCC, CSA, IMQ, SEMKO, UR, VDE	ROHS3 Compliant
GDC-125MA	Eaton	GDC	125	250	Slow Blow	5x20mm	35	0.063	1.97	cURus, IMQ	Not Specified
S506-125-R	Eaton	S506	125	250	Slow Blow	5x20mm	35	0.063	1.97	BSI, CCC, CSA, IMQ, SEMKO, UR, VDE	ROHS3 Compliant
0034.3108	SCHURTER	FST 5x20	125	250	Slow Blow	5x20mm	35	0.064	Not Specified	CCC, cURus, VDE	ROHS3 Compliant
0218.125HXP	Littelfuse	218	125	250	Slow Blow	5x20mm	35	0.1465	4.2	CCC, CE, CSA, K-MARK, SEMKO, UL, VDE	ROHS3 Compliant
0218.125MXP	Littelfuse	218	125	250	Slow Blow	5x20mm	35	0.1465	4.2	CCC, CE, CSA, K-MARK, SEMKO, UL, VDE	ROHS3 Compliant
0218.125TXP	Littelfuse	218	125	250	Slow Blow	5x20mm	35	0.1465	4.2	CCC, CE, CSA, KC, SEMKO, UL, VDE	ROHS3 Compliant
0034.3763	SCHURTER	FSL 5x20	125	250	Slow Blow	5x20mm	35	0.161	Not Specified	cULus	ROHS3 Compliant

Engineering Selection Recommendations

Eaton Direct Equivalents (Recommended for Direct Replacement):

BK/S506-125-R, BK1/S506-125-R, and S506-125-R are direct Eaton alternatives with identical electrical characteristics (Melting I²t: 0.063, DC Cold Resistance: 1.97 Ω) and expanded approval certifications including BSI, CCC, CSA, IMQ, SEMKO, UR, and VDE. These parts maintain full functional equivalence with the main part and are suitable for direct substitution in all applications where BK/GDC-125MA is specified.

Eaton GMD Series (Parametric Equivalent with Variance):

BK/GMD-125-R matches all primary electrical and mechanical parameters but exhibits different thermal characteristics (Melting I²t: 0.043 vs. 0.063) and significantly higher DC Cold Resistance (8.125 Ω vs. 1.97 Ω). This part is approved by CSA and UL. Selection of this variant requires confirmation that the application tolerates the altered thermal response profile.

Cross-Manufacturer Alternatives:

SCHURTER 0034.3108 (FST 5x20 series) and 0034.3763 (FSL 5x20 series) provide parametric equivalence with melting I²t values of 0.064 and 0.161 respectively. Both are ROHS3 compliant and carry relevant certifications. Littelfuse 0218.125HXP, 0218.125MXP, and 0218.125TXP (218 series) are functionally equivalent with melting I²t of 0.1465 and DC Cold Resistance of 4.2 Ω, supported by comprehensive international certifications.

Product Status Consideration:

All listed substitute parts maintain Active product status, ensuring continued availability and manufacturer support.

Frequently Asked Questions (FAQ)

Q: Can BK/S506-125-R be used as a direct replacement for BK/GDC-125MA?

A: Yes. BK/S506-125-R is a direct Eaton equivalent with identical current rating (125 mA), voltage rating (250 V AC), response time (Slow Blow), package dimensions (5x20mm), and breaking capacity (35A). The melting I²t (0.063) and DC cold resistance (1.97 Ω) are identical. This part carries expanded certifications and is suitable for direct substitution.

Q: What is the difference between Eaton GDC and S506 series fuses?

A: Both series meet the same electrical and mechanical specifications for the 125 mA, 250 V rating. The primary differences are the approval certifications and series designation. S506 series carries broader international certifications (BSI, CCC, CSA, IMQ, SEMKO, UR, VDE) compared to GDC series (cULus, IMQ).

Q: Why do Littelfuse 218 series fuses have higher melting I²t values?

A: Melting I²t is a thermal characteristic that reflects the fuse's energy absorption capacity. Littelfuse 218 series parts (0.1465) have higher values than Eaton GDC/S506 series (0.063), indicating different thermal response profiles. Both are classified as Slow Blow response, but the thermal energy handling differs. Application requirements must be verified before substitution.

Q: Are all substitute parts RoHS compliant?

A: All listed substitute parts are either RoHS Compliant or ROHS3 Compliant. The main part BK/GDC-125MA is RoHS Compliant. Cross-manufacturer alternatives (SCHURTER and Littelfuse) are ROHS3 Compliant, which represents an updated compliance standard.

Q: Can I use SCHURTER 0034.3763 (FSL 5x20) instead of BK/GDC-125MA?

A: SCHURTER 0034.3763 matches all primary electrical and mechanical parameters (125 mA, 250 V, Slow Blow, 5x20mm, 35A breaking capacity). However, the melting I²t is 0.161, significantly higher than the main part (0.063). This indicates a different thermal response. Substitution requires verification that the application tolerates this thermal characteristic variance.

Q: What does "Requires Holder" mean for mounting type?

A: All listed fuses are cartridge-type components that require installation in a compatible fuse holder. The 5mm x 20mm form factor is standardized, and any holder designed for 5x20mm cartridge fuses will accommodate all listed parts. The holder itself is not included with the fuse.

Q: Are there any DC voltage rating differences among the substitutes?

A: All listed parts are rated for 250 V AC. DC voltage ratings are not specified in the provided data. Verification of DC voltage compatibility with the application circuit is required before substitution.

Q: Which substitute part has the lowest inventory?

A: GDC-125MA (Eaton, same series as main part) has the lowest inventory at 793 pieces. BK1/S506-125-R has the highest inventory at 1978 pieces among Eaton alternatives.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message