Top Circuit Breaker Replacement Parts That Help You Avoid Costly Panel Upgrades

A circuit breaker that has stopped working properly does not always need to be replaced, and replacing it does not always mean a new panel. Often the fault is in one part that can be changed on its own: a rating plug, a shunt trip, an undervoltage release, a closing coil, a lug kit, a handle or a small repair part. When the breaker frame, contacts and mechanism are sound and the equipment still suits the load, replacing that part can return the breaker to service.

That does not hold in every case. A breaker that is damaged, fails testing or is under-rated for the system has to be replaced, and no accessory changes that. This guide goes through the nine types of circuit breaker part BRAH Electric lists, what each one does, and which breaker families they are made for.

Circuit breaker replacement parts at a glance

The table covers the part types under Circuit Breakers in the BRAH catalogue. The families column names the breaker lines the listed parts are made for.

For anything not in the table, call (855) 355-2724 with the part number.

When a replacement part is enough, and when it is not

Replacing a part makes sense when the fault is isolated to that part. Typical cases are a burnt shunt trip or undervoltage coil, a rating plug that is missing or is the wrong value for the load, a lug that has overheated, or a handle or bumper that has broken. The breaker itself is still mechanically and electrically sound.

A part will not fix a breaker or a panel with a deeper problem. Plan on replacing the breaker, or on a larger upgrade, when:

• the load has grown beyond the rating of the breaker frame, the bus or the feeder conductors;
• the available fault current is higher than the interrupting rating of the breaker;
• the breaker fails its trip or insulation tests, or its main contacts or mechanism are damaged;
• the case is cracked or shows burn or tracking marks, or the bus and enclosure are damaged;
• the breaker has been under water or in a fire.

If you are not sure which side of that line a breaker is on, have it tested by a qualified service provider before buying parts for it.

Rating plugs: setting the trip rating

A rating plug sets the ampere rating of the electronic trip unit in a breaker. It is chosen against the current sensor in the breaker: one catalogue example is a 150A plug for use with a 200A sensor. A plug can set the rating at or below the sensor rating. It does not raise the capacity of the frame, the bus or the cables, and changing the rating is an engineering decision that has to respect the conductor size and the coordination study.

BRAH lists rating plugs for GE Spectra Series molded case breakers in the SE, SF, SG and SK frames, for GE Power Break and AKR breakers with MicroVersaTrip RMS-9 or MicroVersaTrip Plus trip units, for Siemens SB Series breakers, and for Square D breakers with MicroLogic Series 3B trip units. Examples are the BE-SRPG600A600 and the BE-TR16B1600. Each has its own guide: SRPG600A600 and TR16B1600.

Shunt trips: tripping a breaker remotely

A shunt trip is a coil that trips the breaker when a control voltage is applied to it. It is how a remote push button, a fire alarm panel or a protection relay opens a breaker. The coil voltage must match the control circuit. BRAH lists shunt trips for GE Power Break I breakers in the small and large frames and for Merlin Gerin Compact CM breakers, in voltages from 12VDC to 480/600VAC. One example is the 24VDC BE-TPST8.

Undervoltage releases: tripping on loss of control voltage

An undervoltage release works the other way round. It trips the breaker when its control voltage drops out, and the breaker will not stay closed until the voltage returns. It is used where equipment must not restart on its own after a power loss. BRAH lists 18 undervoltage releases for GE Power Break I breakers, from 12VDC to 600VAC. The GE TPUV8 guide lists the whole series with the breaker types each one fits.

Closing coils: closing a breaker remotely

A closing coil, also called a closing release, closes an electrically operated breaker when it receives a control signal. With a failed coil, the breaker cannot be closed by its remote control circuit. BRAH lists closing coils for Merlin Gerin Masterpact MP breakers rated 800A to 5000A in two voltage ranges, such as the BE-685654CC for 110/127VAC and 100/110VDC.

Lug terminal kits: cable connections

Lugs clamp the incoming and outgoing cables to the breaker terminals. A lug that has run hot, stripped its thread or cracked should be replaced, because a poor connection keeps heating until it damages the breaker. The details that matter are the wire range, the number of barrels and the number of lugs in the kit. BRAH lists lug terminal kits for Merlin Gerin Compact CJ, CK and NS/NSF frames, for Siemens/ITE Sentron QJ2, QJH2, QJ2H and HQJ2H frames and for Square D NE and NX frames. Examples are the CK3L and the BTA1Q300.

Face plates: replacement nameplates

The face plates BRAH lists are laser etched replacement nameplates. A nameplate that is missing or unreadable makes a breaker hard to identify and to operate correctly. BRAH lists face plates for GE Power Break I breakers, in older and newer styles, manually and electrically operated, small and large frame, and for GE HPC II switches, top fed and bottom fed. One example is the PB1NSES.

Mounting brackets for breakers and accessories

A mounting bracket holds a breaker in the panel or an accessory inside the breaker. BRAH lists two mounting brackets: the LC-ILINE-FOOT, an I-Line mounting foot for Square D LC and LX frame breakers, and the PCSNTBRKT, a bracket for mounting shunt trips in Westinghouse/Cutler-Hammer Seltronic PC frame breakers.

Operating handles and handle extensions

The operating handle is what the operator uses to open, close and reset the breaker. A broken handle takes a sound breaker out of use. BRAH lists operating handles for Merlin Gerin Compact CM frame breakers rated 1250A to 3200A: the CMHNDL handle and the CMHNDLEX handle extension.

Repair parts: lug caps, bumper kits, clips and switches

Repair parts are the small items that wear, break or get lost during maintenance. The BRAH listing includes lug caps for GE Spectra SE and SF frames such as the SEPLUGCAP, bumper kits for GE Power Break II, TJL4V and TKL4V breakers such as the PB2-BUMP, a ready-to-close indication switch for Merlin Gerin Masterpact, crowns for Square D LA and MA breakers, and an adaption clip used when fitting a shunt trip to Square D FA/FAL frame breakers.

Before you order: what to check

• The breaker. Record the manufacturer, family, frame type and frame rating from the breaker nameplate. Parts are specific to a frame.
• The part number on the old part. It is the surest cross-reference. Search for the OEM number on the BRAH site.
• Coil voltage. For shunt trips, undervoltage releases and closing coils, measure the control supply and note whether it is AC or DC.
• Trip unit and sensor. For rating plugs, record the trip unit type and the sensor rating. A plug is made for one trip unit family.
• Wire size. For lug kits, check the conductor size and the number of conductors per phase against the wire range of the kit.
• The cause. If a coil burnt out or a lug overheated, find out why before fitting the new part.

BRAH Electric designs its parts in-house and tests them at its Carlsbad, California facility. It is an aftermarket manufacturer and is not an authorized distributor of the OEM brands named here. These parts carry a 2-year warranty from the date of invoice, and in-stock orders placed before 3:00 PM Pacific ship the same business day. For help identifying a part, call (855) 355-2724, Monday to Friday, 6AM to 5PM Pacific.

Safety when replacing breaker parts

Most of these parts are fitted with the breaker out of service, and some require removing its cover. De-energize the breaker and any separate control supply, apply lockout/tagout, and verify the absence of voltage first. The work should be done by qualified personnel following the breaker manufacturer’s instructions. Test the breaker before returning it to service: a shunt trip, undervoltage release or closing coil should be proven by operating it.

Circuit breaker replacement part FAQs

Can replacing a part always avoid a panel upgrade?

No. It avoids one only when the breaker and panel are otherwise sound and correctly rated. If the load or the available fault current has outgrown the equipment, or the breaker is damaged, a part will not solve it.

Can a rating plug increase the capacity of my breaker?

A rating plug sets the trip rating within the limit of the sensor fitted to the breaker. It does not increase the rating of the frame, the bus or the cables. Any change of rating should be reviewed by the engineer responsible for the system.

What is the difference between a shunt trip and an undervoltage release?

A shunt trip opens the breaker when voltage is applied to its coil. An undervoltage release opens the breaker when its voltage is removed. They are separate parts and are not interchangeable.

How do I find the right part for an older breaker?

Start with the number on the part you are replacing and the frame type on the breaker nameplate, then search the circuit breaker parts listing. If the number is worn off, call (855) 355-2724 with the breaker details.

Why do circuit breaker parts fail?

Coils fail from heat, age or the wrong control voltage. Lugs fail from loose connections and the heating that follows. Handles, bumpers and other mechanical parts wear or break with use. Finding the cause matters as much as changing the part.

References

• UL 489, Molded-Case Circuit Breakers, Molded-Case Switches and Circuit-Breaker Enclosures. The UL standard that covers molded-case circuit breakers.
• NFPA 70B, Standard for Electrical Equipment Maintenance.
• OSHA 29 CFR 1910.147, The control of hazardous energy (lockout/tagout).
• NFPA 70E, Standard for Electrical Safety in the Workplace.