Special Installations and Locations (Hazardous Areas, Medical, Wet Areas, Construction Sites)
Special locations override the general rules of AS/NZS 3000, and questions test the specific standard and the key control. Hazardous areas use the AS/NZS 60079 series: classify the zone (gas Zones 0, 1, 2; dust Zones 20, 21, 22), identify the gas/dust group and temperature class, then select Ex equipment with the correct marking (e.g. Ex d, Ex e, Ex i) and wiring method. Medical locations use AS/NZS 3003: patient areas require equipotential bonding, isolated supplies or RCDs depending on the group, and stricter limits on leakage and fault loop. Wet areas (bathrooms, pools) require supplementary bonding, RCD protection and zone-based restrictions on equipment location. Construction sites use AS/NZS 3012: robust wiring, RCD protection on all circuits, regular inspection and testing, and protection against mechanical damage.
Traps: treating a hazardous area as a normal area with a heavier enclosure; forgetting that Zone 0/20 permits only the most highly protected equipment (e.g. Ex ia); using a standard RCD where medical location rules demand specific arrangements; and missing the periodic verification requirements for construction sites.
Worked example: A workshop storing flammable solvent vapour is classified Zone 1. You must select equipment marked for Zone 1, with the correct gas group and temperature class, and install it using a wiring system permitted for that zone - a standard IP-rated enclosure is not sufficient regardless of how robust it looks.