Buyer Guide: Explosion Proof and Intrinsic Safety Devices

Explosive 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”, and are defined by the National Electrical Code (NEC) in the US, or the Canadian Electrical Code (CEC) in Canada. When equipment must be installed in hazardous locations, there are strict requirements for the construction of the installation, including materials and design requirements. To prevent inadvertent ignition of flammable gases and vapors by electrical equipment, the two most common methods of protection are “Explosion Proof” and “Intrinsically Safe”.

  • An "explosion proof" classification for a sensor/transmitter means that the housing has been engineered and constructed to contain a flash or explosion. Such housings are usually made of cast aluminum or stainless steel and are of sufficient mass and strength to safely contain an explosion should flammable gases or vapors penetrate the housing and the internal electronics or wiring cause an ignition. The design must prevent any surface temperatures that could exceed the ignition temperature of the gases or vapors covered by its Group rating.
  • An "intrinsically safe" classification and design means that an electronic circuit and it’s wiring will not cause any sparking or arcing and cannot store sufficient energy to ignite a flammable gas or vapor, and cannot produce a surface temperature high enough to cause ignition. Such a design is not explosion proof, nor does it need to be. For permanent installations, such an installation may include “intrinsically safe barriers” that are located outside the hazardous location, and limit the amount of energy available to the device located in the hazardous area.

The North American classifications for hazardous locations as related to flammable gases and vapors: Class I: Gases and vapors

Division 1: Gases or vapors are usually present and/or may be present at any time in sufficient concentrations for an explosion hazard.

Division 2: Gases or vapors are not normally present and are present only in the event of a leak in some kind of containment vessel or piping, again in potentially hazardous concentrations.

Groups A, B, C, D: Groups of atmospheres categorized by the volatility and/or ignition temperatures. “A” is the most hazardous and “D” is the least hazardous group for gases and vapors.

  • Group A: Atmospheres containing acetylene.
  • Group B: Atmospheres containing hydrogen or gases or vapors of equivalent hazard.
  • Group C: Atmospheres containing ethyl-ether vapors, ethylene, or cyclo-propane.
  • Group D: Atmospheres containing gasoline, hexane, naptha, benzene, butane, propane, alcohol, acetone, benzol, lacquer solvent vapors, or natural gas (methane).


Pros and Cons

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 can’t be used for all applications. It is simply impossible to run certain types of devices, such as lighting fixtures and motors, on such low currents and voltage.

Maglocks offers a full line of products to support intrinsic Safety design and implementation. If you would like one of our advisors and help with your product requirements or answer any open questions, give us a call 888.500.5625. We would be happy to assist.



MC-HD176 Explosion Proof UL listed maglock, 600lbs

UL listed explosion proof magnetic lock for use in Class 1 Div 2 All Groups A, B, C, D environments.

Standard Features:

  • UL Certified for Class 1 Div 2 All Groups A, B, C, D Environment,
  • Only Singles Available (use two for double door applications).
  • Built-In Spike or Surge Suppressions.
  • Satin Anodized Aluminum Finish.
  • Functionality for utilization as a door contact switch - Form "C" contact.
  • The only UL (Underwriters Labs) approved explosion proof maglock.

Technical Specifications:

  • Holding Force 600lbs at 24VDC, (324lbs at 12VDC)
  • 0.25 Amps - 24VDC, (0.50 Amps - 12VDC)
  • Approx. size 10 ½” x 2” x 2”


  • MC-HD176 24: single maglock for outswing doors, push side mount. 24VDC.
  • MC-HDZB176 24: single maglock for inswing doors, pull side mount. 24VDC. *

* must be specific for UL Certification. Inswing maglocks come with the required inswing bracket assembly.

Explosion Proof Handing Diagram



Explosion Proof Devices

Visit our full line of Explosion Proof Devices including pust-to-exit buttons, readers, magnetic locks and door closures.



We are here to help

If you would like one of our advisors and help with your product requirements or answer any open questions, give us a call 1.866.500.5625. We would be happy to assist. Simply, complete the project planner form below and we will contact you to discuss ways we may assist. When you complete the project planner, we will add your email to our newsletter to keep you informed of industry news and special offers. You may amend your subscription, at any time, to limit contact.

Door Access Control Project

* indicates required
Is A Usage Log Needed?