Epoxy Certified for UL 1203 Standard

UL 1203 certified epoxy for explosion-proof and dust-ignition-proof electrical equipment for use in hazardous locations

2 min read
Master Bond EP41S-6 meets UL 1203 standard for explosion-proof and dust-ignition-proof electrical equipment in hazardous locations.

Underwriters Laboratories (UL) 1203 is defined as the “Standard for Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous (Classified) Locations." To certify an epoxy for the UL1203, sample castings are exposed to saturated vapors in air for the following chemicals:


UL then assesses the performance of each set of castings in the manner described above: for 168 hours of exposure to the chemicals noted. After exposure to these vapors, the castings in groups of 6 are observed for discoloration, swelling, shrinking, crazing, cracking, leaching, and dissolving. Also, the crushing force needs to be not less than 85 % of the original value in order for the product to be deemed to be suitable for use without exception.

Master Bond EP41S-6: Tested for UL1203

Master Bond EP41S-6 is a two part epoxy system, which resisted each and every chemical without exception, and therefore is suitable for use in Class I, Division 1, Groups A, B, C, and D, and Class II, Division 1, Groups E, F, and G, in accordance with the NEC (National Electrical Code), NFPA 70 (National Fire Protection Association).

The NEC classifies potentially explosive environments into 3 distinct classes: fire or explosion hazards from:

Class I – flammable gases, vapors or liquids,

Class II – combustible dusts, and

Class III – ignitable fibers.

Division 1 represents an area where flammable or hazardous conditions can exist under normal operating conditions.


A – Acetylene,

B – Hydrogen,

C – Ethylene, and

D – Propane;


E – Metal Dusts,

F – Carbonaceous Dusts, and

G – Non-Conductive Dusts

Master Bond EP41S-6 meets UL 1203 standard for explosion-proof and dust-ignition-proof electrical equipment in hazardous locations.

The optimal cure schedule for EP41S-6 is overnight at room temperature, followed by 6-8 hours of heat curing at 150-250°F. This compound features good flow properties, with a dielectric strength of 440 volts/mil for 0.125 inches thick specimens, making it ideal for sealing and potting applications for electrical feedthroughs across various industries.

Download the complete case studies and learn how this epoxy might benefit your application.

The Conversation (0)

Smokey the AI

Smart image analysis algorithms, fed by cameras carried by drones and ground vehicles, can help power companies prevent forest fires

7 min read
Smokey the AI

The 2021 Dixie Fire in northern California is suspected of being caused by Pacific Gas & Electric's equipment. The fire is the second-largest in California history.

Robyn Beck/AFP/Getty Images

The 2020 fire season in the United States was the worst in at least 70 years, with some 4 million hectares burned on the west coast alone. These West Coast fires killed at least 37 people, destroyed hundreds of structures, caused nearly US $20 billion in damage, and filled the air with smoke that threatened the health of millions of people. And this was on top of a 2018 fire season that burned more than 700,000 hectares of land in California, and a 2019-to-2020 wildfire season in Australia that torched nearly 18 million hectares.

While some of these fires started from human carelessness—or arson—far too many were sparked and spread by the electrical power infrastructure and power lines. The California Department of Forestry and Fire Protection (Cal Fire) calculates that nearly 100,000 burned hectares of those 2018 California fires were the fault of the electric power infrastructure, including the devastating Camp Fire, which wiped out most of the town of Paradise. And in July of this year, Pacific Gas & Electric indicated that blown fuses on one of its utility poles may have sparked the Dixie Fire, which burned nearly 400,000 hectares.

Until these recent disasters, most people, even those living in vulnerable areas, didn't give much thought to the fire risk from the electrical infrastructure. Power companies trim trees and inspect lines on a regular—if not particularly frequent—basis.

However, the frequency of these inspections has changed little over the years, even though climate change is causing drier and hotter weather conditions that lead up to more intense wildfires. In addition, many key electrical components are beyond their shelf lives, including insulators, transformers, arrestors, and splices that are more than 40 years old. Many transmission towers, most built for a 40-year lifespan, are entering their final decade.

Keep Reading ↓ Show less