Essential Tools
Multimeter
Measures voltage (AC/DC), continuity, and amperage. Essential for verifying circuits are dead and diagnosing faults.
Non-Contact Voltage Tester
Pen-style tester that beeps near live voltage. Test on a known-live source before and after each use.
Receptacle Tester
Plugs into an outlet and lights up to show correct/incorrect wiring (open ground, reversed hot/neutral, etc.).
Wire Strippers
Strips insulation without nicking the conductor. Get one with gauged holes for 10–18 AWG.
Lineman's Pliers
Heavy-duty pliers for twisting wires, cutting, and bending. The electrician's primary tool.
Insulated Screwdrivers
Flat and Phillips drivers with insulated handles, rated 1000V. Needed for outlets, switches, and panels.
Fish Tape
Pulls wire through walls, conduit, and ceilings. 25ft is enough for most residential runs.
Flashlight / Headlamp
Panels and junction boxes are dark. Headlamps keep both hands free.
Wire Nuts (Connectors)
Twist-on connectors for splices. Match the color to the wire count and gauge on the package.
Electrical Tape
600V-rated tape for insulating splices and marking wires. Never a substitute for proper connectors.
NM-B Cable (Romex)
Standard indoor residential wiring cable. Match gauge to breaker size (see wire chart below).
Boxes (Device / Junction)
All splices must live in an accessible box. Plastic (non-metallic) boxes for Romex; metal with conduit.
Wire Size Chart
Copper wire ampacity at typical residential temperatures — always match breaker size to wire.
| Wire | Max Amps | Breaker | Typical Use |
|---|---|---|---|
| 14 AWG | 15 A | 15 A | Lighting, standard outlets |
| 12 AWG | 20 A | 20 A | Kitchen outlets, bathrooms, garages, GFCI circuits |
| 10 AWG | 30 A | 30 A | Water heater, AC condenser, dryer (some) |
| 8 AWG | 40 A | 40 A | Electric range, large appliances |
| 6 AWG | 55 A | 50 A | Range/oven, subpanel feed |
| 4 AWG | 70 A | 60–70 A | Subpanel feed, large loads |
What Size Breaker?
Typical circuit sizing by load. Always confirm with the appliance nameplate.
| Load | Breaker | Wire | Notes |
|---|---|---|---|
| Lighting circuit | 15 A | 14 AWG | Up to ~12 outlets/lights is common. |
| General outlets (bedroom, living) | 15 A or 20 A | 14 or 12 AWG | 20A for more headroom; match wire to breaker. |
| Kitchen countertop | 20 A × 2 | 12 AWG | Two 20A small-appliance circuits required by code; GFCI protected. |
| Bathroom | 20 A | 12 AWG | GFCI-protected receptacle circuit. |
| Electric dryer | 30 A | 10 AWG | 240V, 4-wire (NEMA 14-30) in modern homes. |
| Electric water heater | 30 A | 10 AWG | 240V dedicated circuit. |
| Electric range/oven | 40–50 A | 8 or 6 AWG | 240V dedicated; check appliance nameplate. |
| Central AC / Heat pump | 30–60 A | Per nameplate (MIN circuit ampacity) | Size from the unit's data plate — not guesswork. |
| Garbage disposal / dishwasher | 15–20 A | 14 or 12 AWG | Often shared; dedicated is cleaner. |
Sizing Rules of Thumb
- Match wire to breaker: breaker ampacity must never exceed the wire's ampacity rating.
- Continuous loads (running 3+ hours) should only use 80% of the breaker's rating — a 20A circuit carries 16A continuous.
- Voltage drop matters on long runs: over ~100 ft, go one gauge larger.
- Always read the appliance nameplate — it lists minimum circuit ampacity (MCA) and max breaker size.
