Special occupancies and special equipment
Scope
Special occupancies and equipment questions cover Articles 500-516 (hazardous locations), 517 (health care), 518-520 (assembly), 525, 547, 550, 590, 680 (pools), 690 (solar), 695 (fire pumps), 700 (emergency), 705 (interconnected), and low-voltage Articles 725, 760, 770. The exam tests location classification and listed equipment.
Core rules
- Hazardous locations are classified by Class, Division or Zone, and gas or dust group. Equipment must be listed for the classification, not merely heavy duty.
- Intrinsically safe circuits depend on a control drawing; keep IS wiring separated from non-IS wiring and label it.
- Pool and spa low-voltage luminaires need listed pool transformers and must follow Article 680 bonding and installation rules.
- Fire alarm circuits (Article 760) and optical fiber (Article 770) have their own cable and survivability requirements.
- Temporary wiring (Article 590) is not a permanent installation; GFCI protection and support rules still apply.
Worked example
A 24 VDC pressure transmitter is installed in a Class I, Division 1 area and is powered through an intrinsically safe barrier located in the safe area. The installer must follow the barrier manufacturer control drawing: correct barrier, maximum cable length and capacitance/inductance, separate raceway from non-IS circuits, and labels. Simply using a 24 V Class 2 supply does not make the circuit intrinsically safe.
Traps
Assuming low voltage is safe in a hazardous location; mixing IS and non-IS conductors; using a general-purpose enclosure outdoors; omitting pool bonding; and treating fire alarm cable as ordinary Class 2 cable.