Electrical Equipment and Devices
This domain tests devices and equipment: switches, receptacles, GFCI and AFCI protection, panelboards, disconnects, motors, and the clearances and ratings that keep them safe. The exam often asks whether a device is permitted, not just how to wire it.
Core rules
- Switches must be rated for the load and generally be connected in the ungrounded conductor, not the grounded conductor.
- Receptacles: rating and grounding type must match the circuit. GFCI protection is required in dwelling bathrooms, kitchens, garages, outdoors, basements, and other 210.8 locations. AFCI protection is required for dwelling branch circuits serving outlets in living areas under 210.12.
- Panelboards need working clearance: 30 in wide, 36 in deep, 6.5 ft high, or the greater dimensions in 110.26. Circuit directories must be accurate.
- Motor disconnects must be within sight and readily accessible (430.102); overload and branch-circuit protection are separate functions.
- Equipment must be listed and used per instructions; conductor terminations use the 60°C, 75°C, or 90°C column per 110.14(C).
Worked example
A 1,500 W, 120 V continuous load is on a dedicated branch circuit. What minimum overcurrent protection? Load current = 1,500 / 120 = 12.5 A. Continuous load: OCPD ≥ 125% × 12.5 = 15.625 A (210.20(A)). A 15 A breaker is too small. The next standard rating is 20 A, so use a 20 A circuit with 12 AWG copper and a 20 A receptacle; verify terminal temperature ratings and ampacity after any derating.
Traps
- Applying the 125% continuous factor to the conductor but not the overcurrent device, or vice versa.
- Confusing GFCI (ground-fault shock protection) with AFCI (arc-fault fire protection).
- Installing a 20 A receptacle on a 15 A circuit.
- Reverse-wiring a GFCI by swapping line and load, so downstream outlets are unprotected.
- Ignoring 110.26 working clearance when placing a panel.
- Assuming a disconnect can serve as motor overload protection.