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NEC Article 500 · FM Certified · Class I Div 1 & 2

Explosion-Proof Circuit Breakers
for Hazardous Locations

Class I Division 1 & 2 · Groups A–D · T6 Rated · FM & UL Listed
— Stocked in Houston & New Orleans, Shipped Nationwide

✓ NEC Article 500 Compliant FM File #301885 Class I Div 1 & 2 Groups A · B · C · D T6 Rated · In Stock Ships Same Day

What Are Explosion-Proof Circuit Breakers?

An explosion-proof circuit breaker is a circuit protection device housed in a reinforced enclosure designed to contain any internal arc, spark, or explosion — preventing ignition of flammable gases, vapors, or combustible dust in the surrounding atmosphere. They are required by the National Electrical Code (NEC) in any classified hazardous location.

Unlike standard circuit breakers, explosion-proof models are built to UL 1077, UL 508, FM, and CSA standards and must be certified for the specific hazardous location class, division, and group where they will be installed. The enclosure is designed so that if an internal arc occurs during a fault, the explosion is contained within the housing and hot gases are cooled before escaping — eliminating the risk of igniting the external atmosphere.

Explosion-proof circuit breakers are used as branch circuit protection, control circuit protection, and supplementary protection in hazardous location control panels, junction boxes, and motor control centers. They are commonly installed on DIN rails inside NEMA 7 or NEMA 9 enclosures.

Industrial Equipment Company stocks CRI APBM series explosion-proof circuit breakers — FM certified, Made in New Orleans, and rated for Class I Division 1 and Division 2 locations. Available in 1A through 20A DC ratings and 1A through 15A AC ratings.
Key Requirements
Governing Standard NEC Article 500–506
Required Certifications FM, UL, or CSA
Enclosure Rating NEMA 7 (Class I) / NEMA 9 (Class II)
Installation Standard NEC 501.115 / NFPA 70
Inspection Authority AHJ (Authority Having Jurisdiction)
Marking Requirement Class, Division, Group, T-Code
Key Takeaways

What You Need to Know About Explosion-Proof Circuit Breakers

  • ✓Explosion-proof circuit breakers are required by NEC Article 500 in any classified hazardous location where flammable gases, vapors, or combustible dust may be present.
  • ✓Class I Division 1 locations require fully explosion-proof equipment; Class I Division 2 locations may use nonincendive (non-sparking) equipment under normal operating conditions.
  • ✓Hazardous Groups A–D classify the type of flammable gas or vapor. Group D (propane, natural gas) is the most common in oil & gas; Groups A and B (acetylene, hydrogen) are the most severe.
  • ✓The T-code (temperature rating) must be lower than the auto-ignition temperature of the hazardous substance. T6 (85°C max) is the safest and most broadly applicable rating.
  • ✓Required certifications include FM, UL, or CSA. The enclosure must be rated NEMA 7 for Class I (gas/vapor) or NEMA 9 for Class II (dust) hazardous locations.
  • ✓Common industries requiring explosion-proof breakers include oil & gas, petroleum refineries, chemical plants, paint spray booths, marine/offshore, grain elevators, and wastewater treatment facilities.
  • ✓The CRI APBM series is FM certified (File #301885), T6 rated, rated for Groups A–D, and available in DC 1–20A and AC 1–15A. Made in New Orleans, LA. Stocked by Industrial Equipment Company in Houston and New Orleans.
  • ✓Industrial Equipment Company is an authorized stocking distributor of CRI explosion-proof circuit breakers with same-day shipping from Houston, TX and New Orleans, LA.

NEC Hazardous Location Classifications

Understanding Class, Division, and Group is essential for selecting the correct explosion-proof equipment.

CLASS I — DIVISION 1

Continuously Hazardous

Flammable gases or vapors are present continuously, intermittently, or periodically under normal operating conditions. Equipment failure could release hazardous concentrations.

TYPICAL LOCATIONS
Interiors of spray booths · Inadequately ventilated pump rooms · Areas adjacent to open tanks of flammable liquids · Interiors of refrigerators storing flammable materials
Required: Fully Explosion-Proof Equipment
CLASS I — DIVISION 2

Abnormal Conditions Only

Flammable materials are present only under abnormal conditions — such as a container failure, equipment malfunction, or inadequate ventilation. Under normal operation, concentrations are below hazardous levels.

TYPICAL LOCATIONS
Adequately ventilated storage areas · Locations adjacent to Div 1 areas · Areas where flammable liquids are handled in closed systems · Outdoor petrochemical facilities
Permitted: Nonincendive (Non-Sparking) Equipment

Hazardous Material Groups — Class I

Group Representative Gas Common Substances Typical Industry CRI APBM Rated
Group A Acetylene Acetylene gas, welding operations Metal fabrication, chemical ✓
Group B Hydrogen Hydrogen gas, butadiene, ethylene oxide Chemical, semiconductor, refinery ✓
Group C Ethylene Ethylene, cyclopropane, ethyl ether Petrochemical, plastics, pharmaceutical ✓
Group D Propane Propane, butane, natural gas, gasoline, benzene Oil & gas, refinery, pipeline, marine ✓

Temperature Codes (T-Codes)

The T-code indicates the maximum surface temperature of the equipment. It must be lower than the auto-ignition temperature of the hazardous substance present.

T-Code Max Surface Temp Suitable For CRI APBM
T1 450°C (842°F) Most substances —
T2 300°C (572°F) Acetylene, hydrogen —
T3 200°C (392°F) Gasoline, jet fuel —
T4 135°C (275°F) Ethylene, acetaldehyde —
T5 100°C (212°F) Carbon disulfide —
T6 ★ 85°C (185°F) Most conservative — suitable for all Group A–D substances ✓

★ CRI APBM series breakers are T6 rated — the most conservative and widely applicable temperature code.

CRI APBM Series — FM Certified · Class I Div 1 & 2 · In Stock · Ships Same Day Order Now →

Industries Requiring Explosion-Proof Circuit Breakers

Any facility where flammable gases, vapors, or combustible dust may be present is subject to NEC hazardous location requirements.

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Oil & Gas Production
Wellheads, pump jacks, compressor stations, gas processing facilities, pipeline metering stations. Groups C and D — propane, natural gas, H₂S.
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Petroleum Refineries
Distillation units, cracking units, hydroprocessing, tank farms, loading racks. Multiple groups — gasoline, benzene, ethylene, hydrogen.
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Chemical & Petrochemical
Chemical reactors, solvent handling, ethylene plants, polymer production. Groups A–D depending on specific chemicals processed.
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Paint Spray Booths
Automotive finishing, industrial coating operations, wood finishing. Solvent vapors — typically Group D. Often Class I Division 1 during spraying operations.
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Marine & Offshore
Offshore platforms, tank vessels, bilge areas, fuel handling areas. ATEX and IECEx equivalents required for international vessels. Groups C and D.
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Grain & Agricultural
Grain elevators, feed mills, flour mills, starch processing. Class II (combustible dust) — Groups E, F, G. Requires NEMA 9 enclosures for dust-ignitionproof equipment.
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Wastewater Treatment
Digester areas, pump stations, enclosed wet wells. Methane (Group D) and hydrogen sulfide (Group C) are common hazards in wastewater facilities.
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Pharmaceutical
Solvent extraction, tablet coating, fermentation. Ethanol and other solvent vapors — typically Group C or D. FDA-regulated facilities with strict electrical safety requirements.
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Power Generation
Gas turbine enclosures, hydrogen-cooled generators, fuel handling areas, battery rooms. Groups B (hydrogen) and D (natural gas) are common in power generation facilities.
Ready to Order CRI Explosion-Proof Breakers?
DC 1–20A & AC 1–15A · Groups A–D · T6 Rated · FM File #301885 · Made in New Orleans
 Order Now → Request a Quote

How to Select the Right Explosion-Proof Circuit Breaker

Four steps to ensure you specify the correct breaker for your hazardous location application.

01
Determine the Classification
Identify the NEC Class (I, II, or III), Division (1 or 2), and Group (A–G) for your specific location. This is determined by the type and concentration of hazardous material present.
02
Verify the T-Code
Look up the auto-ignition temperature of the hazardous substance. Select a breaker with a T-code whose maximum surface temperature is below the substance's ignition temperature. T6 is the safest choice.
03
Select Amperage & Voltage
Size the breaker for the circuit load — typically 125% of continuous load per NEC 210.20. Confirm the voltage rating matches your system (AC or DC, 24V, 120V, 240V, etc.).
04
Confirm Certification
Verify the breaker carries the required FM, UL, or CSA certification for your Class, Division, and Group. Request the certification documentation and FM file number for your records and AHJ inspection.

Our Stocked Solution: CRI APBM Series

Industrial Equipment Company stocks CRI explosion-proof circuit breakers — FM certified, Made in New Orleans, and rated for Class I Division 1 and 2 locations across Groups A, B, C, and D.

CRI APBM SERIES — KEY SPECS
Classification Class I Div 1 & 2, Groups A–D
Temperature Rating T6 (85°C max surface)
DC Amperage Range 1A, 2A, 3A, 5A, 7A, 10A, 15A, 20A
AC Amperage Range 1A, 2A, 3A, 5A, 7A, 10A, 15A
Certification FM File #301885 · UL 1077 · CSA 22.2
Enclosure NEMA 7 & 9 rated
Mounting DIN Rail (IEC 60715)
Made In New Orleans, Louisiana, USA
View CRI APBM Part Numbers & Pricing →

Why CRI?

Made in the USA — New Orleans, LA
CRI breakers are manufactured in New Orleans, Louisiana — not overseas. Consistent quality, domestic supply chain, and fast replenishment.
FM Certified — File #301885
Factory Mutual certification is the gold standard for hazardous location equipment. FM File #301885 covers the full APBM series.
Stocked in Texas & Louisiana
We stock CRI breakers at our Houston and New Orleans locations. Same-day shipping on in-stock items. No waiting on overseas lead times.
Custom Panel Builds Available
Need a complete hazardous location control panel? We can source CRI breakers alongside ASCO solenoid valves, Fireye controls, and other components for a complete solution.
Documentation Available
Spec sheets, FM certificates, wiring diagrams, and installation drawings available on request for all CRI APBM models.
Have your part number? Order directly from our online store — no account required. Order Now →

Frequently Asked Questions

What is an explosion-proof circuit breaker?
An explosion-proof circuit breaker is a circuit protection device housed in an enclosure designed to contain any internal arc or explosion and prevent ignition of surrounding flammable gases, vapors, or dust. They are rated for use in NEC-classified hazardous locations and must be FM, UL, or CSA certified for the specific hazardous location class and group.
What is the difference between Class I Division 1 and Class I Division 2?
Class I Division 1 locations have flammable gases or vapors present continuously, intermittently, or periodically under normal operating conditions. Class I Division 2 locations have flammable materials present only under abnormal conditions — such as a container failure or equipment malfunction. Division 2 allows the use of nonincendive (non-sparking) equipment, which is less costly than fully explosion-proof Division 1 equipment.
What hazardous groups do CRI explosion-proof breakers cover?
CRI APBM series breakers are rated for Groups A, B, C, and D — covering acetylene, hydrogen, ethylene, propane, butane, natural gas, and gasoline vapors. This covers the vast majority of oil and gas, petrochemical, and industrial applications.
What is a T-code or temperature rating?
The T-code indicates the maximum surface temperature of the equipment under normal operation. It must be lower than the auto-ignition temperature of the hazardous substance present. T6 (85°C maximum) is the most conservative rating — suitable for all Group A–D substances. CRI APBM breakers are T6 rated.
Can I use a standard circuit breaker in a hazardous location?
No. Standard circuit breakers are not approved for use in NEC-classified hazardous locations. Using non-rated equipment in a hazardous location is a code violation and creates a serious explosion and fire risk. All electrical equipment in classified areas must be specifically rated and certified for the applicable class, division, and group.
What is the difference between explosion-proof and intrinsically safe?
Explosion-proof equipment contains any internal ignition within its enclosure. Intrinsically safe equipment operates at energy levels too low to ignite a hazardous atmosphere — no containment needed. Intrinsically safe is used for low-power instrumentation; explosion-proof is used for higher-power devices like circuit breakers, motors, and lighting.
What industries require explosion-proof circuit breakers?
Oil and gas production, petroleum refineries, chemical and petrochemical plants, grain handling facilities, paint spray booths, marine and offshore platforms, wastewater treatment, pharmaceutical manufacturing, and any other location where flammable gases, vapors, or combustible dust may be present.
Where can I buy CRI explosion-proof breakers in Texas and Louisiana?
Industrial Equipment Company stocks CRI APBM series breakers at our Houston, TX and New Orleans, LA locations. Same-day shipping on in-stock items. Call 713-928-3181 (Houston) or 504-734-1147 (New Orleans), or request a quote online.

Need Explosion-Proof Circuit Breakers?

We stock CRI APBM series in Houston and New Orleans. Same-day shipping on in-stock items.

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