FWH-70B Equivalent & Substitute Parts

Part Overview

The FWH-70B is a 70A cartridge fuse rated for 500 VAC/VDC operation with bolt mount configuration, manufactured by Eaton - Bussmann Electrical Division. This part is classified as obsolete, making identification of equivalent and substitute components necessary for system maintenance and component replacement in electrical and industrial applications. The FWH-70B delivers 200kA AC and 50kA DC breaking capacity at rated voltage with a melting I²t value of 210.

Substiute Parts

FWH-70B

Eaton - Bussmann Electrical DivisionIn Stock: 1138FWH-70B Datasheet

Current PartRFQ

FWH-70BC

Eaton - Bussmann Electrical DivisionIn Stock: 929FWH-70BC Datasheet

MFR RecommendedRFQ

L50S070.T

Littelfuse Inc.In Stock: 947L50S070.T Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the FWH-70B are identified based on electrical and mechanical parameter alignment. The primary substitution criteria are:

• Current Rating: 70A (exact match required)
• Voltage Rating - AC: 500 VAC (exact match required)
• Fuse Type: Cartridge (exact match required)
• Mounting Type: Bolt Mount (exact match required)
• Package / Case: Cylindrical, Blade Terminal (Bolt) (exact match required)
• Breaking Capacity @ Rated Voltage: 200kA AC minimum (AC specification)

The FWH-70BC qualifies as a manufacturer-recommended substitute, maintaining all critical electrical parameters while offering active product status and enhanced certifications. The L50S070.T qualifies as a similar substitute with equivalent AC voltage and current ratings, though DC voltage rating differs at 450 VDC versus 500 VDC, and DC breaking capacity is reduced to 20kA.

Parameter Comparison

Engineering Selection Recommendations

The FWH-70BC is the primary substitute for the obsolete FWH-70B. Both parts are manufactured by Eaton - Bussmann Electrical Division and maintain identical electrical specifications: 70A current rating, 500 VAC/VDC voltage ratings, 200kA AC and 50kA DC breaking capacity, and 210 melting I²t. The FWH-70BC offers active product status and expanded certifications including CSA and UL approval, providing enhanced availability and regulatory compliance for new installations and replacements.

The L50S070.T from Littelfuse Inc. serves as an alternative substitute when FWH-70BC availability is constrained. This part maintains the 70A current rating, 500 VAC voltage rating, and 210 melting I²t specification. However, the DC voltage rating is reduced to 450 VDC, and DC breaking capacity is specified at 20kA compared to 50kA for the FWH-70B. Selection of the L50S070.T requires confirmation that the application DC voltage requirement does not exceed 450 VDC and that the reduced DC breaking capacity is acceptable for the circuit protection scheme.

Frequently Asked Questions (FAQ)

Q: Can the FWH-70BC directly replace the FWH-70B in all applications?

A: Yes. The FWH-70BC maintains identical electrical and mechanical specifications to the FWH-70B across all critical parameters: 70A current rating, 500 VAC/VDC voltage ratings, bolt mount configuration, and 200kA AC/50kA DC breaking capacity. The FWH-70BC is the manufacturer-recommended substitute.

Q: What are the limitations of using the L50S070.T as a substitute?

A: The L50S070.T has a reduced DC voltage rating of 450 VDC compared to the FWH-70B specification of 500 VDC. Additionally, DC breaking capacity is 20kA versus 50kA for the original part. These differences require application review to confirm compatibility with circuit voltage and fault current requirements.

Q: Are there physical dimension differences between these cartridge fuses?

A: Yes. The FWH-70B and FWH-70BC share identical cylindrical, blade terminal (bolt) package configuration. The L50S070.T has different physical dimensions: 1.000" diameter × 2.126" length (25.40mm × 54.00mm) compared to the FWH series 0.950" diameter × 1.740" length (24.13mm × 44.20mm). Physical fit in the fuse holder must be verified before installation.

Q: Which substitute part offers the best regulatory compliance?

A: The FWH-70BC provides the broadest certification coverage with CE, CSA, and UL approvals. The L50S070.T carries CE, CSA, and UR certifications. Both parts meet major regulatory standards; selection depends on specific regional and application requirements.

Q: What is the melting I²t specification, and is it the same across all three parts?

A: Melting I²t is a thermal characteristic indicating the energy required to melt the fuse element. All three parts—FWH-70B, FWH-70BC, and L50S070.T—share an identical melting I²t value of 210, ensuring consistent thermal response characteristics.