NOTE: This is an unformatted excerpt from our online fire protection training library.
Zone Classification
Type of Protection "n"
Type "n" is equivalent to nonincendive.
This protection type has three variations:
"Na" - Nonsparking equipment
"Nc" - Sparking equipment in which contacts are suitably protected by a method other than restricted breathing. (Similar to "nonincendive components" as defined in Article 500)
"Nr" - Restricted breathing enclosure (Sometimes hermetically sealed or otherwise constructed so that flammable gases and vapors will not enter the enclosure or will enter too slowly to make a hazard likely.) This equipment must be marked "Caution - Restricted breathing device. To maintain restricted breathing properties, a seal must be provided on all conduit or cable entries."
© Hughes Associates,Inc. 2012
NOTE: This is an unformatted excerpt from our online fire protection training library.