What is the difference between SPB-50, SPB-65, SPB-100, and SPB-150?

The SPB-50 (50 kA), SPB-65 (65 kA), SPB-100 (100 kA), and SPB-150 (150 kA) differ only in interrupting capacity at 480V. The SPB-50, SPB-65, and SPB-100 are electrically and mechanically identical in external dimensions — the higher interrupting capability comes from internal component differences (arc chutes, contacts). The SPB-150 uses a larger frame. This means an SPB-100 is a direct drop-in replacement for an SPB-50 or SPB-65 with no cubicle modifications required.

What are the SPB breaker catalog number prefixes and what do they mean?

SPB catalog numbers use prefixes that indicate the breaker configuration: SR/R = standard breaker, MR = motor-operated, HR = high-interrupting (150 kA), WR = wide-frame, WHR = wide high-interrupting, N = non-automatic switch, NH = non-automatic high-withstand. The "M" prefix variants (e.g., MSR) indicate metric construction. The full catalog number encodes frame size, trip unit type, sensor rating, and factory-installed accessories.

What is an SPB edge number and how do I read it?

The SPB edge number is a 30-digit code stamped on the breaker frame edge. Positions 1–10 encode the Westinghouse-era style number (e.g., 8702C## for newer Eaton, 7805C## for older Westinghouse). Positions 11–30 are a 20-digit option code covering 13 fields: mounting type, connection method, trip unit, sensor rating, shunt trip voltage, undervoltage release, auxiliary switches, motor operator, and other factory-installed options. The edge number is the definitive identifier for ordering exact replacement parts.

Which Digitrip RMS trip units are compatible with SPB breakers?

SPB breakers are compatible with the full Digitrip RMS family. Each model (310 through 910) is available in LS, LSI, LSG, and LSIG catalog suffix variants depending on protection functions ordered: RMS 210 (basic LI protection), RMS 310 (basic metering, IL 29C883E), RMS 510 (zone interlocking, IL 29-885), RMS 610 (advanced metering + communications, IL 29-886), RMS 810 (full protection suite, IL 29-888), and RMS 910 (power quality monitoring, IL 29-889). The Pow-R Trip 7 is a legacy standard LSIG trip unit. All trip units require a matching rating plug sized to the breaker frame and sensor. Voyten stocks all models and rating plugs.

How do I identify my SPB breaker model and order replacement parts?

To identify your SPB breaker: (1) Locate the nameplate on the breaker front — it shows the catalog number, style number, and frame/trip ratings. (2) Check the edge number stamped on the breaker frame for detailed configuration. (3) Note the trip unit model (visible on the trip unit face). With any of these identifiers, contact Voyten Electric at 1-800-458-4001 or visit spbbreakers.com — their team can cross-reference to the exact renewal parts needed.

Technical Reference Guide

Eaton Type SPB Systems Pow-R BreakerComplete Technical Reference — Models, Specifications & Parts Guide

Everything you need to know about the Eaton/Cutler-Hammer/Westinghouse Type SPB insulated case circuit breaker — from model identification and specifications to trip unit selection, upgrade paths, and parts sourcing.

What Is the SPB Breaker?

The Type SPB (Systems Pow-R Breaker) is a low voltage insulated case circuit breaker (ICCB) manufactured continuously since 1976. It is one of the most widely deployed ICCBs in North American industrial, commercial, and utility power distribution systems.

The breaker has been produced under three brand names — Westinghouse (original manufacturer), Cutler-Hammer (after Eaton's acquisition of Westinghouse's electrical division), and Eaton (current branding). All three nameplates represent the same product lineage with full parts interchangeability.

SPB breakers are offered in two mounting families. In drawout form, the breaker rides a cassette that racks between Connected, Test, and Disconnected without disturbing primary bus connections — the cell stays wired while the breaker is pulled for testing or renewal-part work. In fixed-mount form (also called bolt-in or stationary), the breaker is bolted directly to the bus with front- or rear-connected terminals — typical in feeder applications where racking access isn't required. Frames span 800–5000A, with interrupting capacities from 50 kA to 150 kA RMS symmetrical at 480V.

Drawout breakers ship with one of two factory door interfaces:

Behind-the-Door (BTD) — breaker and cassette are fully enclosed by the cell door; operating, racking, and trip-unit access all require opening the door. Cleanest gear face and maximum environmental protection for the operating mechanism and trip unit.
Through-the-Door (TTD) — the trip unit display and manual operators project through an escutcheon in the cell door, letting operators read Digitrip / Pow-R Trip 7 settings, check trip status, and rack with the door closed and latched. Typically specified where arc-flash mitigation and routine diagnostic access drive the design.

SPB Model Lineup

Model	Designation	Interrupting (480V)	Frame Range	Notes
SPB-50	SPBSR	50 kA	800–3200A	Same frame as SPB-65/100
SPB-65	SPBSR	65 kA	800–3200A	Same frame as SPB-50/100
SPB-100	SPBR	100 kA	800–3200A	Drop-in for SPB-50/65
SPB-150	SPBHR	150 kA	800–5000A	Larger frame
SPBN	Non-automatic	N/A	800–5000A	Switching duty, no trip
SPBNH	Non-automatic	N/A	800–5000A	High-withstand switch

SPB-50/65 to SPB-100 Upgrade Path

Drop-In 100 kA Upgrade — No Structural Modifications

Applicable to all SPB-50 and SPB-65 installations

The SPB-50, SPB-65, and SPB-100 are electrically and mechanically identical in external dimensions. The difference in interrupting rating is achieved entirely through internal components — different arc chutes, moving contacts, and stationary contacts.

This means an SPB-100 will slide directly into an existing SPB-50 or SPB-65 cubicle with zero modifications to the surrounding structure, bus connections, or control wiring. For facilities whose available fault current has grown past the original 50 or 65 kA rating, this provides a clean, cost-effective upgrade to 100 kA without replacing switchgear.

Note: The SPB-150 uses a different (larger) frame and is not a drop-in replacement for SPB-50/65/100 cubicles.

Catalog Number Prefixes

SPB catalog numbers begin with a prefix that encodes the breaker type and configuration:

Prefix	Meaning	Interrupting
SR / R	Standard breaker	50/65/100 kA
MR	Motor-operated breaker	50/65/100 kA
HR	High-interrupting breaker	150 kA
WR	Wide-frame breaker	50/65/100 kA
WHR	Wide high-interrupting breaker	150 kA
N	Non-automatic switch	N/A
NH	Non-automatic high-withstand switch	N/A

“M” prefix variants (MSR, MHR, etc.) indicate metric construction for IEC applications.

Understanding the SPB Edge Number

Every SPB breaker has a 30-digit edge number stamped on the breaker frame. This is the definitive identifier for ordering exact replacement parts and is more specific than the catalog number.

Edge Number Structure

Positions 1–10: Westinghouse/Eaton style number (e.g., 8702C## for newer Eaton production, 7805C## for older Westinghouse production)
Positions 11–30: 20-digit option code encoding 13 configuration fields — mounting type, connection method, trip unit, sensor rating, shunt trip voltage, undervoltage release, auxiliary switches, motor operator, and other factory options

When contacting Voyten for parts, providing the edge number ensures an exact match to your breaker's specific configuration — including the correct mounting style, connection type, and factory-installed accessories.

Trip Units & Rating Plugs

SPB breakers use interchangeable electronic trip units that provide adjustable overcurrent protection. The trip unit mounts to the breaker front and connects via a rating plug sized to the breaker's sensor.

Trip Unit	Protection	Features
Pow-R Trip 7	LSIG	Standard legacy trip unit
Digitrip RMS 910	LS / LSI / LSG / LSIG	Power quality monitoring (IL 29-889)
Digitrip RMS 810	LS / LSI / LSG / LSIG	Full protection suite (IL 29-888)
Digitrip RMS 610	LS / LSI / LSG / LSIG	Advanced metering, communications (IL 29-886)
Digitrip RMS 510	LS / LSI / LSG / LSIG	Ground fault, zone interlocking (IL 29-885)
Digitrip RMS 310	LS / LSI / LSG / LSIG	Basic metering (IL 29C883E)
Digitrip RMS 210	LI	Basic overcurrent protection

L = Long-time, S = Short-time, I = Instantaneous, G = Ground fault. All trip units require a matching rating plug.

Brand History & Nameplate Cross-Reference

The SPB breaker has been manufactured under three brand names due to corporate acquisitions. All three nameplates represent the same product with full parts interchangeability:

Westinghouse

Original manufacturer (1976–1994)

Style: 7805C##

Cutler-Hammer

Eaton acquisition era (1994–~2010)

Style: 8702C##

Eaton

Current branding (~2010–present)

Style: 8702C##

Parts from any era are interchangeable. A Westinghouse-branded SPB-100 uses the same renewal parts as an Eaton-branded SPB-100 of the same frame size.

Renewal Parts Categories

Voyten Electric stocks the following SPB renewal part categories for immediate shipment:

Trip Units & Rating Plugs

Electrical Attachments

Auxiliary Switches

Electrical Operator Kits

Gear / Motors

Handles / Hub Assemblies

Key Interlock Provisions

Shunt Trip Kits

Spring Release Kits (400–5000A)

Terminals / Drawout Stabs

Undervoltage Release Devices

Breaker Covers

Need SPB Parts or Technical Support?

Voyten Electric is the New Surplus authorized aftermarket source for the complete SPB product line. New and reconditioned breakers, trip units, rating plugs, and every renewal part — tested, in stock, and backed by 1 year warranty.

1-800-458-4001 Request a Quote

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