Equipment Protection Levels (EPLs) tell buyers how strongly equipment is protected against becoming an ignition source in an explosive atmosphere. For gas hazards, Ga provides very high protection, Gb high protection and Gc enhanced protection. They are normally associated with Zones 0, 1 and 2, respectively.
That difference matters when choosing a videoscope or inspection camera for a refinery, chemical plant or other classified location. A camera approved for Gc cannot be assumed suitable for Zone 1 or Zone 0. The full Ex marking, site classification and approved configuration still control where it may be used.
For the broader relationship between areas and equipment categories, see AIT's ATEX ratings for inspection cameras.
Quick answer: Ga is typically suitable for gas Zones 0, 1 and 2; Gb for Zones 1 and 2; and Gc for Zone 2 only, provided every other part of the approval also matches. A higher protection level does not make gas group, temperature class or certificate conditions optional.
Ga, Gb and Gc Mean Different Levels of Ignition Protection
The letters follow the IEC 60079 equipment protection system. The capital G identifies an explosive gas atmosphere; the lowercase letter describes protection against becoming an ignition source under different operating and fault conditions. Those conditions are the reason a Zone 0 instrument needs a different approval from one intended for Zone 2.
Designed so it is not an ignition source during normal operation, expected malfunctions or rare malfunctions. Typically required for gas Zone 0.
Designed so it is not an ignition source during normal operation or expected malfunctions. Typically associated with gas Zone 1.
Designed not to ignite the atmosphere during normal operation, with additional protection possible for specified regular expected events. Typically associated with gas Zone 2.
Descriptions such as "two faults" and "one fault" can help with a basic explanation, but the IEC definition considers expected and rare malfunctions, not a blanket promise about any possible equipment failure. The U.S. Coast Guard's EPL explanation describes these protection levels using the IEC 60079-0 definitions.
Which EPL Is Suitable for Zone 0, Zone 1 or Zone 2?
The classified area is assigned by the facility's responsible personnel. It describes how often an explosive gas atmosphere can exist. EPL describes the protection built into the equipment. These two classifications are related, but they answer different questions.
ATEX Categories 1G, 2G and 3G commonly correspond to Ga, Gb and Gc in IEC-based Ex markings. They are not interchangeable proof of certification under every regulatory scheme. Check the approval intended for the country of use, the certificate and any conditions attached to it.
Site classification comes first: A clean, empty or temporarily shut-down vessel is not automatically declassified. The facility's approved hazard assessment governs the work, even when no flammable vapor is visible.
Where to Find the EPL on a Camera's Ex Marking
The EPL usually appears at the end of an IEC-based Ex marking. AIT's hazardous-area videoscope provides a useful real-world example:
The final Gc identifies its gas equipment protection level. The rest of the marking remains relevant:
Identifies the category and gas-atmosphere application associated with this Zone 2 instrument.
Names the explosion-protection techniques used for the approved equipment design.
Identifies the gas group, T4 surface-temperature class and Gc protection level. None replaces the others.
For how the full sequence is read, see AIT's ATEX marking explanation. The IIA, IIB and IIC hierarchy is covered separately in its gas-group comparison.
What Happens When the Probe Enters a Different Classified Area?
For a portable inspection camera, the operator and probe may not be in the same atmosphere. A technician could stand near a vessel opening in an area classified as Zone 2 while the probe enters an internal space with a different classification. That is a separate equipment-acceptance problem from choosing the correct probe length.
IEC 60079-26 addresses Ex equipment containing parts with different protection levels across a hazardous-area boundary. It does not mean that a standard Gc videoscope can be inserted into Zone 0 by keeping its handset outside. Such an arrangement needs its own documented approval and facility authorization. The IEC 60079-26 standard overview explains the scope of this special case.
How AITVS Fits a Gc Inspection Requirement
AIT VideoScope (AITVS)
AITVS is AIT's articulating videoscope for applicable ATEX Zone 2 and North American Class I Division 2 gas or vapor applications. Its published ATEX marking ends in Gc and includes IIC T4, with separate approvals for the relevant regulatory systems.
It offers 4-way articulation and several probe-diameter and insertion-length options. The exact configuration and safe-use restrictions must be checked before site approval or quotation. AITVS is not approved as a Zone 0 or Zone 1 camera on the basis of its Gc marking.
A 4-way articulating probe, battery and display may be the right inspection tools, but the site still needs to accept the marked system, permitted components and operating conditions. Separate testing claims do not raise a Gc approval to Gb or Ga.
Why Similar Inspection Cameras Can Get Different Site Decisions
Two videoscopes can have comparable imaging, insertion diameter and reach while carrying different Ex approvals. That difference changes where they are permitted to work. A purchase comparison that starts and ends with camera resolution may miss the site restriction that decides whether the instrument can be used.
Gb protection does not compensate for a gas-group marking that fails to cover the site atmosphere.
An otherwise suitable Gc camera can be excluded by an incompatible temperature class.
Class I Division 2 approval does not automatically establish Ga, Gb or Gc suitability. Each approval needs to match the jurisdiction.
For North American gas-group details, AIT also explains Class I Division 2 Groups A, B, C and D. A site that has standardized on ATEX or IECEx should use its own specified approval requirements, not a label translated by assumption.
The Classified Boundary Does Not Appear in the Inspection Image
A probe can pass through a small opening and show a clear image while the surrounding area stays visually unchanged. Yet the site classification may differ across that opening. If the inserted equipment enters an area requiring Gb or Ga protection, a Gc-only videoscope does not become acceptable because the operator remains outside.
For planned shutdowns, tank entries and process inspections, that distinction is worth settling before the access window opens. Otherwise the team may have a working camera, an accessible target and no approved way to make the inspection.
