Devices, Switches, Receptacles, and Outlet and Lighting Installations
Domain 5 tests device-level code knowledge: switch and receptacle rules, lighting outlets, box mounting for devices, and the placement geometry of 210.52.
Switches and lighting outlets
404.2 requires the switch to be within sight of the load unless a disconnecting means is provided, and 404.2(C) requires a grounded conductor at switch boxes controlling lighting loads, with limited exceptions where the wiring method can accommodate one later. 210.70 requires switch-controlled lighting outlets in habitable rooms, bathrooms, hallways, stairways, attached garages, and at exterior entrances; equipment rooms and attic equipment spaces need a lighting outlet too. 410.16 keeps luminaires clear of closet storage - 12 in for surface-mounted incandescent or LED and 6 in for recessed or fluorescent types.
Receptacles
210.52(A) measures 6 ft along the floor line: no point may sit more than 6 ft from a receptacle, so devices typically land no more than 12 ft apart. 210.52(C) requires countertop receptacles so no point is more than 24 in from one, at least one per island or peninsula, and a receptacle for any counter 12 in or wider. 406.12 requires tamper-resistant receptacles in dwellings; 406.9 requires weather-resistant types in damp and wet locations; 406.4(D) governs replacements, permitting a GFCI-protected three-prong receptacle on an ungrounded circuit only with the required marking.
Mounting devices
314.20 requires boxes set back no more than ¼ in from a noncombustible finish and flush with a combustible finish, with gaps over ⅛ in repaired. 406.5 requires receptacles to be mounted securely with a proper cover plate.
Worked example
A 22 ft wall with doorways at both ends: receptacles at 5 ft and 17 ft from the left edge leave a 12 ft gap. The midpoint (11 ft) is 6 ft from each device, and the ends are 5 ft away. The installation satisfies 210.52(A)(1).
Traps
Measuring the 6 ft through a doorway instead of along the floor line; assuming a switch satisfies the lighting-outlet rule without a luminaire; skipping the island receptacle; ignoring box fill when adding a device to an existing box.