Find answers to the most frequently asked questions about circuit breakers, sizing, brands, applications, and costs. All answers from AllBreakerSales.com industry experts.
Categories: Buying Guide | Technical Guide | Brand Comparison | Industry Guide | Local Guide
Yes — provided you buy from a reputable distributor that verifies part authenticity. Look for companies that offer a warranty, list their physical location, and have verifiable customer reviews. Avoid marketplace listings with no return policy or no stated condition.
Read full articleYou need the catalog number (printed on the breaker label), the brand, the amperage, the number of poles, and the voltage rating. If the label is worn, the frame size and trip type can help narrow it down.
Read full articleAllBreakerSales.com offers same-day quotes and ships from US warehouse stock. Call before 4PM EST for same-day processing on in-stock items.
Read full articleYes, when purchased from a reputable supplier who follows NETA or PEARL reconditioning standards. A properly reconditioned breaker has been cleaned, tested, and certified to meet original manufacturer specifications. The key is buying from a supplier who discloses their reconditioning process and offers a warranty.
Read full articleA surplus breaker is new or like-new stock that was never installed — often from a cancelled project, a plant upgrade, or overstock. Surplus parts are typically sold at 30–60% below new list price and carry the same performance as new parts.
Read full articleFor common residential Square D QO breakers, big-box stores are competitive. For commercial I-Line, PowerPact, or Masterpact breakers, specialist distributors like AllBreakerSales.com typically offer better pricing than electrical supply houses, especially on surplus and reconditioned stock.
Read full articleA 200A residential main breaker (Square D QO2200, Siemens Q2200) typically costs $30–$80 new. A 200A commercial MCCB (Square D QDL22200, Eaton EHD) runs $150–$600 depending on the frame and interrupting rating.
Read full articleA 400A 3-pole commercial MCCB (Square D I-Line, Eaton PowerDefense, Siemens HFD) typically costs $400–$1,500 new depending on the frame, interrupting rating, and trip type. Surplus stock is often available at 30–50% below new pricing.
Read full articleHigh-amperage breakers, electronic trip units, draw-out construction, and obsolete/discontinued models all drive prices up. A 2000A air circuit breaker with an LSIG electronic trip unit can cost $15,000–$40,000 new because of the precision engineering and low production volumes involved.
Read full articleAn obsolete breaker that has been properly inspected, tested, and reconditioned to original specifications is safe to use. The key is sourcing from a reputable supplier who discloses the condition and testing process. An untested, uninspected used breaker of unknown history is a different matter.
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In most catalog numbers, the number represents the amperage rating. For example, in Square D HFD36100, the '100' is 100 amps. In Eaton EDB3100, the '100' is also 100 amps. In Siemens HFD62F040, the '040' is 40 amps.
Read full articleThe pole count tells you how many conductors the breaker protects. '1' or '1P' is single-pole (one hot wire, used for 120V circuits). '2' or '2P' is double-pole (two hot wires, used for 240V circuits). '3' or '3P' is three-pole (three hot wires, used for 3-phase 208V or 480V circuits).
Read full articleThe catalog number is printed on the breaker's label, usually on the front face or side. On older breakers, it may be stamped into the case. If the label is worn, look for the frame designation (like 'HFD' or 'EDB') and the amperage rating, which together can identify the part.
Read full articleWestinghouse's circuit breaker division was acquired by Eaton (Cutler-Hammer) in the 1990s. Eaton continues to manufacture some Westinghouse-compatible breakers and is the primary source for Westinghouse replacement parts. Some Westinghouse models have direct Eaton equivalents; others require sourcing original surplus or reconditioned stock.
Read full articleSome are, some aren't. Eaton acquired Westinghouse's breaker business and produces listed replacements for many Westinghouse models. However, not all Westinghouse breakers have a direct Eaton equivalent — particularly older industrial frames. Always verify the UL listing before substituting.
Read full articleGenerally no. Square D breakers are not listed for use in Westinghouse panels. Using an unlisted breaker in a panel violates the NEC and voids the panel's UL listing. The correct approach is to use either original Westinghouse stock or a listed Eaton replacement.
Read full articleThe terms are often used interchangeably, but 'reconditioned' typically implies a more rigorous process — disassembly, cleaning, inspection, repair, and testing to original specifications. 'Refurbished' can mean anything from a simple cleaning to full reconditioning. Always ask what the process involved.
Read full articleNETA (InterNational Electrical Testing Association) publishes standards for testing electrical equipment. A NETA-tested circuit breaker has been tested by a qualified technician to verify that it meets original manufacturer specifications for contact resistance, insulation resistance, trip timing, and other parameters.
Read full articleYes, in most cases. Reconditioned breakers are appropriate for new installations when the part is properly tested and certified. Some specifications or insurance policies may require new equipment — check your project specs before using reconditioned stock.
Read full articleA molded case circuit breaker (MCCB) is a type of circuit breaker — the term refers to the construction where the operating mechanism, contacts, and arc extinguishing system are enclosed in a molded insulating case. MCCBs are used for commercial and industrial applications at higher amperages and voltages than residential breakers.
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Generally no. Circuit breakers are designed to work with specific panelboards and switchgear. A Siemens breaker should not be used in a Square D panel unless it is specifically listed as compatible. Using an incompatible breaker can void the panel's UL listing and create a safety hazard.
Read full articleBoth are tier-one manufacturers with excellent quality and UL listings. Square D (Schneider Electric) has a larger US market share and broader distribution network. Siemens has a strong presence in industrial and switchgear applications. The better choice depends on what's already installed in your facility.
Read full articleSquare D has the widest distribution network in North America, making common parts easier to find locally. Siemens parts are widely available through electrical distributors and specialists. For obsolete or discontinued models, both brands require a specialist distributor.
Read full articleYes. Eaton acquired Cutler-Hammer in 1978 and has continued to sell products under both the Eaton and Cutler-Hammer brand names. Many older breakers are labeled Cutler-Hammer; current production uses the Eaton brand. Parts are fully compatible within the same product line.
Read full articleYes — Eaton and Cutler-Hammer are the same company. Current Eaton breakers are direct replacements for Cutler-Hammer breakers of the same catalog number or equivalent.
Read full articleNo. Eaton and Square D breakers are not interchangeable in each other's panelboards. Each manufacturer's breakers are designed and listed for specific panel enclosures. Using a non-listed breaker in a panel voids the UL listing and creates a safety hazard.
Read full articleA motor circuit protector (MCP) is a type of circuit breaker designed specifically for motor branch circuits. Unlike a standard MCCB, an MCP has only instantaneous (magnetic) trip protection — it does not have thermal overload protection. The thermal overload function is handled by a separate overload relay. MCPs are allowed by NEC 430.52 for motor branch circuit protection.
Read full articleGenerally no. Motor control centers are designed for specific breaker brands and models. Using a non-listed breaker in an MCC violates the UL listing of the MCC. Always use breakers that are listed for your specific MCC manufacturer and model.
Read full articleA standard MCCB provides both thermal (overload) and magnetic (short-circuit) protection. An MCP provides only magnetic (short-circuit) protection — thermal protection is provided by a separate overload relay. MCPs are typically smaller and less expensive for motor applications where a separate overload relay is used.
Read full articleData centers primarily use electronic-trip MCCBs (LSIG) for main and feeder breakers to enable selective coordination — ensuring only the breaker closest to a fault trips while the rest of the facility stays energized. Branch circuits typically use thermal-magnetic breakers. Power distribution units (PDUs) use specialized breakers with remote monitoring capabilities. Main switchgear uses air circuit breakers (ACBs) or power circuit breakers for 1,600A+ applications.
Read full articleSelective coordination means that during a fault, ONLY the breaker immediately upstream of the fault trips — all other breakers remain closed. This prevents a single fault from cascading and taking down multiple circuits or an entire floor. NEC 700.32 and 701.32 require selective coordination for emergency and legally required standby systems. Data centers achieve this using electronic trip breakers with adjustable short-time delay settings.
Read full articleYes. Tier III and IV data centers require concurrent maintainability or fault tolerance, which means every electrical path must have a redundant parallel path. This includes redundant breakers in an A/B power configuration — each server rack receives power from two independent sources through two independent breaker paths. If one breaker trips or needs maintenance, the other path carries the full load.
Read full articleA motor circuit protector is a circuit breaker with magnetic-only trip (no thermal element). It provides short-circuit protection for motor branch circuits while allowing a separate overload relay (in the motor starter) to handle overload protection. MCPs are set to trip at 8-13x motor full-load amps, which allows the high inrush current during motor starting (6-8x FLA) without nuisance tripping. Standard thermal-magnetic breakers would trip during normal motor starting.
Read full articleManufacturing facilities typically have large utility transformers (1,000-10,000 kVA) located close to the electrical equipment. This creates very high available fault currents — often 42,000 to 100,000+ amps at the main switchboard. Every breaker in the system must be rated to safely interrupt these fault levels. Additionally, large motors contribute fault current back into the system during a fault, further increasing the available fault current.
Read full articleNEC 430 requires motor branch circuit protection using either: (1) a standard circuit breaker sized at 250% of motor FLA (thermal-magnetic), or (2) a motor circuit protector (MCP) sized at 800-1300% of motor FLA (magnetic-only). The MCP approach is preferred because it allows normal motor starting without tripping, while the separate overload relay in the starter provides precise overload protection at 115-125% of motor FLA.
Read full articleCommercial building panel size depends on the total connected load. A typical 10,000 sq ft office needs 200-400A service. A 50,000 sq ft retail space needs 800-1600A. A 100,000+ sq ft mixed-use building needs 2000-4000A main service with multiple sub-panels. The electrical engineer performs a load calculation per NEC Article 220 to determine exact sizing. Always plan for 20-30% growth capacity.
Read full articleYes, in specific locations. NEC 210.8(B) requires GFCI in commercial buildings for: bathrooms, kitchens, rooftops, outdoors, indoor wet locations, garages, and locker rooms with showers. NEC 2023 expanded GFCI requirements to include 250V circuits in these locations. Additionally, NEC 230.95 requires ground-fault protection of equipment (GFPE) on services rated 1,000A or more at 277/480V.
Read full articleGFPE (NEC 230.95) is different from personnel GFCI. It protects equipment from arcing ground faults that are too small to trip a standard breaker but large enough to start a fire. Required on 277/480V services rated 1,000A+. Typically set at 1,200A pickup with 1-second maximum delay. This is usually built into the main breaker's electronic trip unit (the 'G' in LSIG).
Read full articleNEC 517.26 divides the essential electrical system into three branches: (1) Life Safety Branch — exit lighting, fire alarms, emergency communication, generator accessories; (2) Critical Branch — patient care lighting, nurse call, medical gas alarms, pharmacy, blood bank, selected receptacles in patient care areas; (3) Equipment Branch — HVAC for critical areas, elevators, sump pumps, medical air compressors. Each branch has its own transfer switch and distribution panel with specific breaker coordination requirements.
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AllBreakerSales.com ships to all Los Angeles ZIP codes (90001-93599) with same-day shipping on orders placed before 2 PM PST. We stock all major brands including Square D, Eaton, Siemens, and GE in residential, commercial, and industrial configurations.
Read full articleYes. The City of Los Angeles Department of Building and Safety requires a permit for most electrical work including breaker replacement. A licensed C-10 electrical contractor must pull the permit. Simple like-for-like residential breaker replacements may qualify for an express permit.
Read full articleSquare D dominates commercial and industrial installations in LA. Eaton/Cutler-Hammer and Siemens are common in residential. Older buildings (pre-1990) often have GE, Westinghouse, or Federal Pacific panels that need replacement or compatible breakers.
Read full articleWe offer same-day shipping from our US warehouse on orders placed before 2 PM PST. Standard ground delivery reaches most LA-area addresses in 1-2 business days. Expedited overnight shipping is available for urgent plant-down situations.
Read full articleAllBreakerSales.com ships to all NYC boroughs and Tri-State ZIP codes with same-day shipping on orders before 2 PM EST. We stock all major brands for residential, commercial, and industrial applications — including hard-to-find obsolete parts for NYC's older building stock.
Read full articleYes. New York City has its own electrical code (NYC Electrical Code) which is based on NEC but includes NYC-specific amendments. Key differences include stricter requirements for high-rise buildings, specific rules for old-law tenements, and additional requirements for fire alarm integration. Always verify NYC-specific requirements with your licensed electrician.
Read full articleSquare D I-Line and PowerPact dominate commercial high-rises. Eaton Pow-R-Line in older commercial buildings. Residential varies by era: newer buildings use Square D QO or Eaton CH; pre-war buildings often have obsolete GE, Westinghouse, or Bulldog panels requiring specialty replacement parts.
Read full articleYes. We offer overnight and 2-day express shipping to all NYC ZIP codes (10001-11697). Same-day shipping on orders placed before 2 PM EST. For emergency plant-down situations, call (877) 611-0034 for expedited handling.
Read full articleAllBreakerSales.com ships to all Miami and South Florida ZIP codes (33001-34997) with same-day shipping on orders before 2 PM EST. We stock hurricane-rated equipment and all major brands for residential, commercial, and industrial applications.
Read full articleYes. Florida Building Code requires equipment rated for the local wind speed zone. In Miami-Dade County, electrical equipment must meet the Miami-Dade Notice of Acceptance (NOA) for products exposed to wind. Indoor panels don't need wind rating, but outdoor equipment and enclosures must be rated for the High-Velocity Hurricane Zone (HVHZ).
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