understanding explosion proof and intrinsic safety devices
Electrical equipment sometimes must be installed in areas where combustible vapors and gases are used or may be present. These are commonly referred to as hazardous locations as defined by the National Electrical Code (NEC) in the US, or the Canadian Electrical Code (CEC) in Canada. To prevent inadvertent ignition, the two most common methods of protection are “explosion proof” and “intrinsically safe”.
Explosion Proof
This classification means the housing is engineered to safely contain a flash or explosion. Cast aluminum or stainless steel enclosures prevent the resulting flame or surface temperature from escaping and igniting the outside atmosphere.
Intrinsically Safe
This design dictates that an electronic circuit and its wiring simply cannot store sufficient energy to ignite a flammable gas, nor produce a surface temperature high enough to cause ignition. It physically prevents sparks or arcing.
Class I: Gases and Vapors Classifications
The North American classifications for hazardous locations strictly dictate what hardware can be used based on the frequency and type of flammable gases present.
Division 1
Gases or vapors are usually present and/or may be present at any time in sufficient concentrations to create an active explosion hazard.
Division 2
Gases or vapors are not normally present. They are present only in the event of an accidental leak or rupture in a containment vessel or piping.
Atmosphere Safety Groups
Groups are categorized by volatility and ignition temperatures. Group "A" represents the most hazardous atmospheres, while Group "D" represents the least hazardous.
Atmospheres containing highly volatile acetylene.
Atmospheres containing hydrogen or gases of equivalent hazard.
Atmospheres containing ethyl-ether vapors, ethylene, or cyclo-propane.
Atmospheres containing gasoline, hexane, benzene, butane, propane, acetone, lacquer solvent vapors, or natural gas (methane).
The Core Difference: Containment vs. Prevention
While both methods protect hazardous environments, they achieve safety in completely opposite ways. Here is a quick reference guide to help you determine the right hardware methodology for your facility.
| Feature | Explosion Proof (Containment) | Intrinsically Safe (Prevention) |
|---|---|---|
| Method of Protection | Built to withstand and contain an internal explosion. It allows the spark to happen, but prevents the resulting flame from escaping the heavy-duty enclosure. | Engineered to strictly limit electrical and thermal energy. It physically prevents sparks or extreme heat from ever occurring in the first place. |
| Hardware Design | Heavy, bulky, cast-aluminum or stainless steel enclosures with tight seals and heavy-duty conduit. | Lightweight, standard-looking devices connected to an energy-limiting "barrier" located safely outside the hazardous zone. |
| Installation & Maintenance | Complex and expensive. Requires specialized rigid conduit and seals. Power must be completely shut off to perform any maintenance. | Easier and more cost-effective. Uses standard wiring. Maintenance and calibration can often be performed while the system is "live." |
Common Industry Applications
Unsure if your facility requires HazLoc rated equipment? Here are a few common commercial and industrial applications where Class I and Division 1 or 2 standards are strictly enforced.
Automotive & Manufacturing
Paint spray booths, finishing areas, and facilities utilizing highly volatile lacquer solvent vapors or acetone.
Oil, Gas & Petrochemical
Offshore drilling rigs, petroleum refineries, and fuel storage facilities where gasoline and methane are present.
Agriculture & Food Processing
Grain silos, flour mills, and processing plants where airborne combustible dust creates severe explosion hazards.
Aviation & Aerospace
Aircraft hangars, fueling stations, and aerospace manufacturing where jet fuels and volatile chemicals are utilized.
Maglocks Expert Recommendation
Intrinsically safe is considered the superior method for hazardous locations since it altogether prevents an explosion from taking place. For this reason, we recommend using this method whenever possible.
The major downside to intrinsic safety is that it cannot be used for all applications. It is simply impossible to run certain high-draw devices, such as heavy lighting fixtures and motors, on such low currents and voltage. In those scenarios, explosion proof containment is required.
Featured Explosion Proof Hardware
Explore our top-rated containment hardware specifically engineered, tested, and UL Listed for volatile environments.
MC-HD176 Explosion Proof Maglock (600 lbs)
UL Listed for Class 1 Div 2 environments. Features a heavy-duty satin anodized aluminum enclosure.
view product →
Heavy-Duty Explosion Proof Exit Button
Cast iron enclosure designed to prevent hazardous atmosphere ignition during emergency egress.
view product →
Explosion Proof Manual Pull Station
High-visibility, corrosion-resistant pull station for immediate alarm triggering in volatile zones.
view product →We Are Here To Assist You
Whether you are in the office or at a job site, we are here for you.
Connect on Social
Follow us for industry news and product updates.