Equivalent & Substitute Parts for Eaton BK/MDA-20 Ceramic Fuse

Part Overview

The Eaton BK/MDA-20 is a 20 A ceramic cartridge fuse rated for 250 V AC and 125 V DC operation. This component is classified as obsolete, requiring identification of active equivalent alternatives for continued system support. The MDA series fuses are designed for applications requiring slow-blow response characteristics and are compatible with 3AB and 3AG holder formats. Substitute parts must maintain identical electrical ratings, mechanical dimensions, and holder compatibility to ensure direct replacement without circuit modification.

Key Parameters

Parameter	Value
Current Rating	20 A
Voltage Rating - AC	250 V
Voltage Rating - DC	125 V
Fuse Type	Cartridge, Ceramic
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (6.35mm x 31.75mm)
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	1.5kA AC, 10kA DC

Substitute Part Grouping Explanation

Substitution eligibility for the BK/MDA-20 is determined by strict alignment of the following critical parameters:

Primary Substitution Criteria (Must Match Exactly):

Current Rating: 20 A
Voltage Rating - AC: 250 V
Voltage Rating - DC: 125 V
Fuse Type: Cartridge, Ceramic
Response Time: Slow Blow
Package / Case: 3AB, 3AG, 1/4" x 1-1/4"
Mounting Type: Requires Holder

Direct Equivalents (All Parameters Match): The following parts satisfy all primary substitution criteria and are classified as direct manufacturer equivalents:

BK/MDA-20-R (Eaton - Electronics Division)
MDA-20-R (Eaton - Electronics Division)
0326020.MXCCP (Littelfuse Inc.)
0326020.VXP (Littelfuse Inc.)

Secondary Substitutes (Voltage Deviation): The following parts match all criteria except DC voltage rating (60 V DC instead of 125 V DC):

0326020.MXDP (Littelfuse Inc.)
0326020.HXP (Littelfuse Inc.)
0326020.MXP (Littelfuse Inc.)

Secondary substitutes are applicable only in circuits where the maximum DC voltage does not exceed 60 V.

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage AC (V)	Voltage DC (V)	Response Time	Breaking Capacity AC (kA)	Breaking Capacity DC (kA)	Melting I²t	DC Cold Resistance (Ω)	Product Status	RoHS Status
BK/MDA-20	Eaton	20	250	125	Slow Blow	1.5	10	439.5	0.00358	Obsolete	Non-compliant
BK/MDA-20-R	Eaton	20	250	125	Slow Blow	1.5	10	483.45	0.004	Active	ROHS3 Compliant
MDA-20-R	Eaton	20	250	125	Slow Blow	1.5	10	483.45	0.004	Active	ROHS3 Compliant
0326020.MXCCP	Littelfuse	20	250	125	Slow Blow	0.4	0.6	575	0.0034	Active	ROHS3 Compliant
0326020.VXP	Littelfuse	20	250	125	Slow Blow	0.4	0.6	575	0.0034	Active	ROHS3 Compliant
0326020.MXDP	Littelfuse	20	250	60	Slow Blow	0.4	0.5	1900	0.0042	Active	ROHS3 Compliant
0326020.HXP	Littelfuse	20	250	60	Slow Blow	0.4	0.5	575	0.034	Active	ROHS3 Compliant
0326020.MXP	Littelfuse	20	250	60	Slow Blow	0.4	0.5	575	0.034	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Electrical Ratings):

Select from the following active parts when 125 V DC rating is required:

BK/MDA-20-R or MDA-20-R (Eaton - Electronics Division) — Preferred primary substitutes. Both parts are active production items from the original manufacturer with ROHS3 compliance. These maintain the Eaton MDA series lineage and are functionally equivalent to the obsolete BK/MDA-20. Inventory availability is substantial (3216 and 696 units respectively).
0326020.MXCCP or 0326020.VXP (Littelfuse Inc.) — Active cross-manufacturer alternatives. Both Littelfuse parts satisfy all electrical and mechanical requirements for 125 V DC applications. These parts carry expanded approval certifications (CE, CSA, KC, PSE, UL) and extended operating temperature range (-55°C to 125°C). ROHS3 compliance is confirmed.

For Reduced DC Voltage Applications (60 V DC Maximum):

The following parts are applicable only when circuit design limits DC voltage to 60 V or below:

0326020.MXDP, 0326020.HXP, or 0326020.MXP (Littelfuse Inc.)

These parts are active production items with ROHS3 compliance and extended temperature ratings. Selection among these three should be based on inventory availability and lead time requirements.

Compliance Considerations:

All recommended substitute parts carry ROHS3 compliance status, addressing environmental regulatory requirements. The original BK/MDA-20 is non-compliant and should not be specified for new designs or long-term system support.

Frequently Asked Questions (FAQ)

Q: Can BK/MDA-20-R or MDA-20-R be used as direct replacements for the obsolete BK/MDA-20?

A: Yes. Both parts are manufactured by Eaton and maintain identical electrical ratings (20 A, 250 V AC, 125 V DC), response characteristics (slow blow), and mechanical dimensions (3AB/3AG, 1/4" x 1-1/4"). Both are active production items with ROHS3 compliance.

Q: What is the difference between the Eaton MDA-20-R variants and the Littelfuse 0326020 series?

A: All parts meet the same electrical and mechanical requirements for 125 V DC applications. Differences exist in breaking capacity ratings (Eaton: 1.5kA AC/10kA DC; Littelfuse: 0.4kA AC/0.6kA DC), melting I²t values, and DC cold resistance. Selection should be based on circuit protection requirements and approval certifications needed for the application.

Q: Can Littelfuse 0326020.MXDP, 0326020.HXP, or 0326020.MXP be used in place of the BK/MDA-20?

A: These parts are suitable only if the circuit design operates at 60 V DC or lower. The DC voltage rating of these parts is 60 V, which is lower than the original 125 V DC specification. Use in circuits exceeding 60 V DC violates the fuse rating and creates a safety hazard.

Q: Are all substitute parts compatible with existing 3AB and 3AG fuse holders?

A: Yes. All listed substitute parts maintain the identical 1/4" x 1-1/4" (6.35mm x 31.75mm) cartridge dimensions and are designed for 3AB and 3AG holder compatibility. No holder modification or replacement is required.

Q: What approval certifications should I verify for my application?

A: The original BK/MDA-20 carries CSA and UL approvals. Eaton MDA-20-R and BK/MDA-20-R carry CE, CSA, and UL approvals. Littelfuse 0326020 series parts carry CE, CSA, KC, PSE, and UL approvals. Verify that the selected substitute meets all certifications required by your application standards and regional regulations.

Q: Why do the Littelfuse parts show lower breaking capacity than the Eaton parts?

A: Breaking capacity is a specified electrical characteristic that differs between manufacturers and product series. Both Eaton and Littelfuse parts are certified for their respective breaking capacity ratings. Selection should be based on the circuit's fault current requirements and the protection scheme design.

Q: Is there a difference in thermal performance between these parts?

A: Littelfuse 0326020 series parts specify an operating temperature range of -55°C to 125°C, while the Eaton parts do not specify an operating temperature range in the provided data. For applications with extreme temperature requirements, the Littelfuse parts provide documented thermal performance specifications.

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