Electrical Work Cheat Sheet

Wire gauges, breaker sizes, and safety guidelines for residential electrical work. Helpful for basic repairs and understanding your home's wiring.

Wire Gauges & Amperage
Wire Gauge (AWG)Max AmperageTypical Use
14 AWG15ALighting circuits, receptacles
12 AWG20AKitchen, bathroom, outdoor receptacles
10 AWG30AElectric dryers, water heaters
8 AWG40AElectric ranges, large AC units
6 AWG55AWelders, large appliances
Wire Types & Cable Designations (NM-B)

Understanding Cable Labels

Cable designations like "14-2" or "12-3" indicate the wire gauge and number of conductors. The first number is the AWG gauge, the second is the number of current-carrying conductors (plus a ground wire which isn't counted).

Cable TypeContainsTypical Use
14-21 black (hot), 1 white (neutral), 1 bare (ground)15A circuits - lights, standard outlets
14-31 black, 1 red, 1 white, 1 bare15A 3-way switches, ceiling fans with separate switch
12-21 black (hot), 1 white (neutral), 1 bare (ground)20A circuits - kitchens, bathrooms, garages
12-31 black, 1 red, 1 white, 1 bare20A 3-way switches, split receptacles, multi-wire branch circuits
10-21 black (hot), 1 white (neutral), 1 bare (ground)30A circuits - electric water heaters, AC units
10-31 black, 1 red, 1 white, 1 bare30A 240V circuits - electric dryers
6-31 black, 1 red, 1 white, 1 bare50A 240V circuits - electric ranges, ovens

Key Differences:

  • 2-wire vs 3-wire: 3-wire cables have an extra hot (red) for 3-way switches or 240V circuits
  • 14 vs 12 gauge: 12 gauge is thicker, handles 20A vs 15A for 14 gauge
  • NM-B vs UF-B: NM-B is for dry indoor use; UF-B is waterproof for underground/outdoor
  • Jacket color: White = 14 AWG, Yellow = 12 AWG, Orange = 10 AWG (common convention)
Circuit Breaker Sizes
Breaker SizeWire GaugeApplication
15A14 AWGStandard lighting and receptacles
20A12 AWGKitchen, bathrooms, laundry
30A10 AWGElectric dryer, water heater
40A8 AWGElectric range, large AC
50A6 AWGElectric range (common size)
Electrical Box Sizes

Single Gang

2" x 3" - One device

Double Gang

2" x 4" - Two devices

Old Work (Retrofit)

For existing walls

New Work

For new construction

Safety Guidelines
  • Always turn off power at the breaker before working
  • Use a non-contact voltage tester to verify power is off
  • Never work on live circuits
  • Use proper wire connectors (wire nuts) - no tape
  • Ground all metal boxes and devices
  • White wire is neutral, black/red are hot, green/bare is ground
  • Leave 6" of wire extending from boxes for connections
  • Staple cables within 8" of boxes and every 4.5 feet
  • GFCI required in bathrooms, kitchens, outdoors, garages
  • AFCI required in bedrooms and living areas (newer codes)
Common Wire Colors & Uses
ColorFunctionNotes
BlackHotAlways assume energized
RedHot (2nd hot)Used in 3-way switches, 240V
WhiteNeutralReturns current to panel
GreenGroundSafety ground
Bare CopperGroundSafety ground
Outlet & Switch Heights

Standard Receptacles: 12-16" above floor

Kitchen Counter Receptacles: 4" above countertop

Switches: 48" above floor (center of box)

ADA Compliant Receptacles: 15-48" above floor

ADA Compliant Switches: 48" maximum above floor

Additional Information

About This Electrical Work Guide

This comprehensive electrical work cheat sheet is designed for DIY homeowners and beginner electricians who need quick access to essential wiring information. Whether you're installing a new outlet, replacing a light switch, or planning a more extensive electrical project, this guide provides the critical specifications you need to work safely and meet code requirements.

Understanding wire gauge sizes, circuit breaker ratings, and proper safety protocols is essential for any electrical work. This reference covers the most common residential electrical scenarios, from determining what size wire for a 20 amp circuit to understanding the color coding of electrical wires. While this guide provides valuable reference information, always consult local building codes and consider hiring a licensed electrician for complex projects or if you're uncertain about any aspect of the work.

Electrical work requires precision and attention to safety. Mistakes can result in fire hazards, code violations, or serious injury. Use this guide as a quick reference, but never skip important safety steps like turning off power at the breaker and verifying circuits are de-energized before beginning work.

Why Use This Electrical Reference Guide?

Having quick access to electrical specifications helps ensure your projects are safe, code-compliant, and professionally executed. This guide saves you time and helps prevent costly mistakes.

  • Quickly determine the correct wire gauge for any amperage requirement
  • Ensure proper circuit breaker sizing to prevent overloads and fire hazards
  • Reference standard outlet and switch heights for consistent, professional installations
  • Understand wire color codes to safely identify hot, neutral, and ground wires
  • Follow critical safety guidelines that protect you and your home
  • Meet electrical code requirements for GFCI and AFCI protection
Frequently Asked Questions

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