Common Switches & Receptacles Reference
Overview
Field reference for the common types of switches + receptacles techs encounter on residential service work. Mis-matching a replacement to its application is a common error - a 15A switch on a 20A circuit is legal in some configurations but illegal in others; a tamper-resistant outlet has different visual indicators. This card resolves the in-truck "what do I need to install here" question.
Reference Table
Standard switches:
| Switch | Use | Amp ratings |
|---|---|---|
| Single-pole | One switch controls one fixture (most common) | 15A or 20A |
| Double-pole | One switch controls 240V load OR two separate circuits | 15A, 20A, 30A |
| 3-way | Two switches control one fixture | 15A or 20A |
| 4-way | Three or more switches control one fixture (used WITH 3-ways) | 15A or 20A |
| Dimmer (LED-rated) | Variable brightness on dimmable LED loads | Typically 600W or 1000W |
| Dimmer (incandescent-only) | Old dimmers; don't work well with LED | Various |
| Occupancy sensor | Auto on/off based on motion | 1800W typical |
| Vacancy sensor | Auto OFF only (manual on); energy savings | 1800W typical |
| Smart switch (Wi-Fi or Z-Wave) | Remote control + automation | 15A typical; requires neutral |
| Timer switch | Time-based on/off | 15A typical |
Standard receptacles:
| Receptacle | Use | Amp / voltage |
|---|---|---|
| Standard duplex | Most residential outlets | 15A / 125V (NEMA 5-15R) |
| 20A duplex | Kitchen counter, laundry, dedicated circuits | 20A / 125V (NEMA 5-20R) |
| GFCI | Bathroom, kitchen counter, outdoor, garage, unfinished basement | 15A or 20A / 125V |
| AFCI | Habitable rooms (when AFCI breakers not used) | 15A or 20A / 125V |
| Dual-function (CAFCI) | Areas needing both AFCI + GFCI (kitchens, laundry per modern code) | 15A or 20A / 125V |
| Tamper-resistant | Required on most receptacles per modern code | 15A or 20A / 125V |
| Weather-resistant | Outdoor + damp locations | 15A or 20A / 125V |
| USB-integrated | Convenience charging outlet | 15A receptacle + USB ports |
| 240V outlet (dryer) | Electric dryer | 30A / 240V (NEMA 14-30R or 10-30R legacy) |
| 240V outlet (range) | Electric range | 50A / 240V (NEMA 14-50R) |
| 240V outlet (EV charger plug-in) | EV charging | 50A / 240V (NEMA 14-50R) |
Specifications
15A vs 20A receptacles:
- 15A receptacle: 2 parallel slots
- 20A receptacle: one T-shaped slot + one parallel slot
- 15A receptacle CAN be installed on a 20A circuit (legal per NEC, if circuit has 2+ outlets)
- 20A receptacle MUST be on a 20A circuit (matches the high-amp T-slot)
- Verify circuit before installing 20A outlet - installing on a 15A circuit allows a load that overheats the wire
Tamper-resistant indicators:
- Look at the slot openings - TR outlets have visible plastic shutters inside that block single-pin insertion
- Modern NEC requires TR receptacles in most residential locations
- Required slot: TR outlets are marked "TR" on the device
Weather-resistant indicators:
- Marked "WR" on the device
- Used outdoors OR in damp locations
- Also typically GFCI-protected at the outlet OR via upstream GFCI
Notes
- GFCI vs AFCI vs DFCI (dual-function): don't confuse. GFCI protects against ground faults (5mA trip). AFCI protects against arc faults (loose connections, damaged wire). Dual-function protects against both. Modern code requires both protections in most habitable areas; dual-function devices simplify the install.
- Backstabbed vs screw-terminal: backstabs work loose over time; screw terminals are the professional standard. NEVER use backstabs on a replacement; screw terminate every wire.
- Smart switch + neutral: most smart switches require a NEUTRAL in the switch box. Many older homes don't have neutrals at switches; this is a common gotcha at quote time.
Tamper-resistant receptacles are REQUIRED by NEC in most residential locations (since 2008 + various updates). Installing a non-TR receptacle in a TR-required area is a code violation. Verify your stock has TR outlets; the cost difference vs standard is small but the code compliance is non-negotiable on inspections.
References
- NEC Articles 210, 406, 408
- Manufacturer device catalogs (Leviton, Pass & Seymour, Hubbell, Lutron)
- Manuall internal: Wire Color Code Reference, Replace a Light Switch