The thing you plug into an outlet is technically called an attachment plug (or cord cap), while the wall device itself is a receptacle. In everyday language, people say 'plug' and 'outlet,' but the National Electrical Code (NEC) strictly defines the wall socket as a receptacle and the pronged connector on your appliance cord as an attachment plug. The wall box housing it is the outlet box, and the assembly is a receptacle outlet.
If your wall receptacle is worn out, loose, or shows scorch marks, replacing it is a fundamental DIY electrical skill. Below is a complete terminology breakdown followed by a professional-grade, step-by-step guide to wiring a standard 120V duplex receptacle.
Receptacle vs. Plug: Getting the Terminology Right
Before pulling out your wire strippers, it helps to speak the language of the trade. Using the correct terminology ensures you buy the right replacement parts at the hardware store and understand electrical safety labels.
| Layman Term | NEC / Pro Term | Definition |
|---|---|---|
| Outlet | Receptacle | The contact device installed at the outlet box for the connection of an attachment plug. |
| Plug | Attachment Plug / Cord Cap | The device attached to the end of a flexible cord, with prongs that insert into the receptacle. |
| Socket | Lamp Holder | Specifically the device that holds a light bulb, not a general power connection. |
| Power Strip | Multi-Outlet Assembly | A corded device providing multiple receptacles, often with surge protection. |
For a deeper look at official definitions, you can reference the National Fire Protection Association (NFPA) NEC guidelines, which govern these terms in Article 100.
Tools, Materials, and Device Ratings
Do not buy the cheapest receptacle on the shelf. Residential-grade 'builder' receptacles (often under $1.00) use thin internal brass contacts that wear out quickly, leading to loose-fitting plugs and arcing hazards. Spend the extra few dollars on commercial-grade or spec-grade devices.
Materials List
- Receptacle: Leviton 5262-W (15A Commercial Grade) or Leviton 5362-W (20A Commercial Grade). Expect to pay $3.50 to $5.00 each.
- Wire Gauge: 14 AWG copper for 15-amp circuits; 12 AWG copper for 20-amp circuits. Never put 14 AWG wire on a 20-amp breaker.
- Wall Plate: Standard 1-gang or 2-gang nylon faceplate (nylon resists cracking better than polycarbonate).
Tool List
- Non-contact voltage tester (NCVT)
- Digital multimeter or plug-in receptacle tester (e.g., Gardner Bender GFI-3501)
- Wire strippers (capable of cleanly stripping 12 and 14 AWG solid wire)
- Lineman's pliers for bending wire hooks
- Phillips and flathead screwdrivers (preferably insulated)
Step-by-Step: Wiring a 120V Duplex Receptacle
Follow these steps to wire a standard 15A or 20A 120V receptacle. This procedure assumes you are working with standard NM-B (Romex) cable containing a black (hot), white (neutral), and bare copper (ground) wire.
- Kill Power and Verify Dead: Turn off the breaker. Test the existing receptacle slots with your NCVT. Insert the probes of your multimeter into the slots to confirm 0V. Remove the old receptacle from the box.
- Prep the Wires: Strip exactly 3/4 inch of insulation from the black and white wires. If the bare copper ground wire is frayed, trim it and strip back 3/4 inch of insulation if it is a green-coated wire, or leave the bare wire clean and straight.
- Connect the Ground (Bare/Green to Green Screw): Loop the bare copper ground wire clockwise around the green grounding screw at the bottom of the receptacle. Tighten firmly. The clockwise loop ensures the screw pulls the wire tighter as you turn it, rather than pushing it out.
- Connect the Neutral (White to Silver Screw): Loop the white neutral wire clockwise around one of the silver-colored screws on the side of the receptacle. Ensure no bare wire is exposed outside the terminal pad, and ensure the wire insulation is not pinched under the screw head. Tighten securely.
- Connect the Hot (Black to Brass Screw): Loop the black hot wire clockwise around one of the brass-colored (gold) screws on the opposite side. Again, ensure a clean connection with no exposed bare copper and no pinched insulation. Tighten securely.
- Fold and Mount: Carefully fold the wires into the back of the electrical box in a Z-pattern (ground first, then neutral, then hot). Push the receptacle into the box and secure it with the provided 6-32 mounting screws. Attach the faceplate, tightening the screws just until snug to avoid cracking the nylon.
The Most Common Botch (and How to Avoid It)
The single most common mistake DIYers make when wiring a receptacle is using the push-in 'backstab' terminals on the back of the device instead of the side-binding screws.
The Symptom: The outlet works fine for a phone charger, but when you plug in a 1500W space heater or a window AC unit, the voltage drops, the plug gets hot, or the power intermittently cuts out. Over time, the tiny internal spring clips in the backstab terminals lose their tension, leading to high-resistance connections, arcing, and melted plastic.
The Fix: Always use the side-binding screws (the 'side-wire' method) as detailed in the steps above. If your wire is 12 AWG and the receptacle only accepts 14 AWG in the backstabs (as many modern devices do), you are physically forced to use the side screws anyway. For 20A circuits, side-wiring is mandatory.
A close second botch is reversed polarity (putting the black wire on the silver screw and the white wire on the brass screw). The lamp will still turn on, but the outer threaded metal shell of the light bulb socket becomes energized at 120V, creating a severe shock hazard if you touch it while changing a bulb.
Verify and Test: Confirming a Safe Installation
Never assume a wiring job is correct just because the device powers on. You must verify the electrical characteristics before plugging in expensive electronics.
- Restore Power: Turn the breaker back on at the panel.
- Plug-in Tester Check: Insert a standard 3-light receptacle tester. You should see two yellow lights illuminated (or the specific 'Correct' pattern indicated on the tester's legend). If you see a red light, you have an open ground or reversed polarity. Turn the breaker back off and check your terminations.
- Multimeter Verification: Set your digital multimeter to AC Voltage (V~).
- Hot to Neutral (Short slot to Long slot): Expected reading is 114V to 126V (120V nominal).
- Hot to Ground (Short slot to Ground hole): Expected reading is 114V to 126V.
- Neutral to Ground (Long slot to Ground hole): Expected reading is less than 2V (ideally 0.0V to 0.5V). A reading higher than 2V indicates a loose neutral connection somewhere upstream or an overloaded shared neutral.
Frequently Asked Questions
What is the thing you plug into an extension cord called?
The pronged end that goes into the wall is the attachment plug. The end with the slots that accepts your appliance is technically a cord connector or a receptacle. The Consumer Product Safety Commission (CPSC) notes that extension cords should only be used temporarily, and the connector end should never be daisy-chained into another extension cord.
What is the plastic cover over the thing you plug into an outlet called?
That is called a wall plate or faceplate. It serves both an aesthetic purpose and a critical safety function by preventing fingers from touching the energized terminal screws inside the electrical box. For wet locations (like outdoors or near sinks), you must use an 'in-use' weatherproof bubble cover that allows the cord to exit while keeping the receptacle sealed from moisture.
What is the thing you plug into an outlet to test it called?
It is called a receptacle tester, outlet tester, or circuit analyzer. Basic models use three neon or LED lights to indicate wiring faults like open grounds, open neutrals, or hot/ground reversals. Advanced digital circuit analyzers also measure the exact voltage, line frequency (Hz), and can simulate a ground fault to trip GFCI receptacles to verify they are functioning correctly.
What do you call the thing you plug into an outlet to get more plugs?
Commonly called a power strip or surge protector, the NEC refers to these as multi-outlet assemblies or relocatable power taps (UL 1363). A crucial distinction: a power strip simply adds outlets, while a surge protector contains metal oxide varistors (MOVs) to clamp voltage spikes. Never plug a high-draw appliance (like a space heater or microwave) into a power strip, as the internal 14 AWG wiring and 15A breaker can easily overheat under continuous heavy loads.
