Type of Protection for Electrical Equipment
The technique of protection which is applied to equipment to prevent the ignition of flammable vapours and gases or combustible dusts in Hazardous areas have a prefix “Ex” most commonly used protection types are outlined below.
| Type of Protection | Description | Standard | Zone |
|---|---|---|---|
| Flameproof enclosure Ex d |
Containment – explosion within an enclosure will not be propagated outside the enclosure. | IEC 60079-1 | Zone 1 & 2 |
| Pressurised enclosure Ex p |
Enclosure in a protective gas is maintained at a pressure greater than that of the external atmosphere. | IEC 60079-2 | Zone 1 & 2 |
| Powder Filling Ex q |
Mounting of potentially incendive components in an enclosure filled with quartz or solid glass particles. | IEC 60079-5 | Zone 1 & 2 |
| Oil Immersion Ex o |
Equipment or parts are immersed in protective liquid such as oil. The protective liquid acts as an insulating medium. | IEC 60079-6 | Zone 1 & 2 |
| Increased safety Ex e |
Non sparking components are designed to substantially reduce the likelihood of the occurrence of fault conditions which could cause ignition. | IEC 60079-7 | Zone 1 & 2 |
| Intrinsic safety Ex i |
The potential spark energy of a circuit is reduced to below the amount required for ignition. | IEC 60079-11 | Zone 0, 1 & 2 |
| Non-sparking Ex n |
Electrical apparatus in normal operating conditions and in certain specified abnormal conditions, that is not capable of igniting a surrounding explosive gas atmosphere. | IEC 60079-15 | Zone 2 |
| Encapsulation Ex m |
Parts that are capable of igniting an explosive atmosphere by either sparking or heating, are enclosed in a compound so that the explosive atmosphere cannot be ignited under operating or installation conditions. | IEC 60079-18 | Zone 0, 1 & 2 |
| Dust protection by enclosure Ex t |
Electrical equipment is protected by the enclosure and surface temperature limitation for use in explosive and dust atmospheres. | IEC 60079-31 | Zone 20, 21 & 22 |
