Chapter 14 Key Takeaways

Wire Types — Know What's in Your Home

• Knob-and-tube buried in attic insulation is a specific fire hazard. Most insurers require its removal or certification.
• Aluminum branch circuit wiring is not an emergency, but does require CO/ALR rated devices at every connection point.

Wire Gauge — The Most Important Specification

• AWG numbers run backward: higher gauge = thinner wire.
• 14-gauge = 15A max. 12-gauge = 20A max. 10-gauge = 30A max.
• The breaker size must match the wire, not the desired load. Oversizing the breaker on undersized wire removes fire protection.
• Never use push-in backstab connections. Always use screw terminals.

Outlet Types — Right Device, Right Location

• GFCI: Required in bathrooms, kitchens (near sinks), garages, outdoors, basements, crawl spaces. One upstream GFCI can protect all downstream outlets on the circuit via LOAD terminals.
• AFCI: Required in bedrooms, living areas, and most rooms in new work under current NEC. Protects against arc faults that cause fires.
• Tamper-resistant (TR): Required in new construction; inexpensive; worth using everywhere when replacing outlets.
• USB outlets: Useful but not a lifetime product — the USB electronics eventually fail while the receptacle continues to work.

Switch Types — Match the Switch to the Job

• Single-pole: One switch, one light.
• Three-way: Two switches, one light (stairways, hallways).
• Dimmer: Must be rated for your specific bulb type. LED dimmers differ from incandescent dimmers. Never use a light dimmer on a motor.
• Smart switches: Most require a neutral wire at the switch box. Switch loops in older homes often lack a neutral.

Junction Boxes — Non-Negotiable

• Every wire splice must be in an accessible junction box with a cover plate.
• Burying a junction box behind drywall or flooring violates NEC 314.29 and creates a fire hazard.
• Box fill limits must be respected — overfilling damages insulation and causes heat buildup.

Safe DIY Outlet Replacement

Always do before touching anything: 1. Turn off the circuit breaker 2. Verify with a non-contact voltage tester (NCV tester) that the outlet is dead 3. Test the NCV tester on a known-live circuit first 4. Test every wire in the box — other circuits may share the box

Connection rules: - Black wire → brass screw (hot) - White wire → silver screw (neutral) - Bare copper → green screw (ground) - Always use screw terminals, never backstab - J-hook the wire clockwise around the screw; tighten firmly

After: Verify with outlet tester that all three indicators show correct.

Warning Signs Requiring Attention

• Scorch marks, discoloration, or burning smell at any outlet or switch
• Warm outlet or switch plate
• Buzzing, crackling, or flickering lights
• Outlet hot/neutral reversed (shock hazard)
• Repeated circuit breaker trips without clear cause
• Outlets that stop working in groups (failed connection upstream)

Permits and DIY

• Replacing an existing outlet or switch in-kind: Usually no permit required; within homeowner capability.
• Adding new circuits: Permit required; licensed electrician in most jurisdictions.
• Sub-panel, service work, any 240V circuits: Permit required; licensed electrician.
• The permit inspection catches mistakes before they become fires. Pull the permit.

Red-Line Safety Rules

• Turn off the circuit breaker AND verify with a non-contact tester before touching any wiring.
• Never assume a box has only one circuit's wires. Test every conductor.
• Never work inside the panel cover.
• If you find aluminum wiring, call an electrician before proceeding.