AS NZS 60079.15:2020 Explosive atmospheres Part 15: Equipment protection by type of protection “n” (IEC 60079-15:2017 (ED.5.0) MOD).
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60079-0 and the following apply.
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devices and components “nC”
hermetically-sealed device “nC”
device which is so constructed that it cannot be opened and is sealed effectively by fusion to prevent entry of an external atmosphere
non-incendive component “nC”
component having contacts for making or breaking a specified ignition capable circuit but in which the contacting mechanism is designed and constructed so that the component is not capable of causing ignition of the specified explosive gas atmosphere
Note 1 to entry: The enclosure or the non-incendive component is not intended to either exclude the explosive gas atmosphere or contain an explosion. This is usually applied to specially constructed switch contacts that are mechanically designed to quench any arc or spark so that they are not a source of ignition.
sealed device “nC”
device which is so constructed that it cannot be opened during normal service and is sealed effectively to prevent entry of an external atmosphere
normally sparking device
device with spacings in line with the industrial requirements and which produces arcs and sparks during normal operating conditions
Note 1 to entry: Normally sparking devices include switches, relays, and contactors not otherwise Ex protected.
restricted-breathing enclosure “nR”
enclosure that is designed to restrict the entry of gases, vapours and mists
sealing device
device employing a method other than encapsulation to prevent the flow of a gas or a liquid between equipment and a conduit or between separate parts of the equipment by providing sealing facilities
Note 1 to entry: This device is not a device covered by IEC TS 60079-40.
shortest distance through solid insulating material between two conductive parts.AS NZS 60079.15 pdf download.