Electrical Outlet Diagram: How to Wire a Standard Duplex Receptacle

Electrical Outlet Diagram: How to Wire a Standard Duplex Receptacle — interactive diagram. Open it in the editor to customise components and wiring.

This is a free printable electrical outlet diagram: download the diagram as SVG or open it and print to paper or PDF.

An electrical outlet (duplex receptacle) connects to a hot, neutral, and ground conductor from the circuit wiring, with terminal screws colour-coded to identify each connection and prevent dangerous wiring errors.

A standard duplex receptacle (electrical outlet) in a North American residential installation is a 3-wire device with six terminal screws arranged in three pairs. Each pair corresponds to one of the three conductors in the circuit wiring. The colour coding of the terminal screws is universal and is one of the most important safety conventions in residential electrical work.

Terminal identification:

1. Brass (gold) screws — Hot (Line): Located on the right side of the receptacle when the face is toward you. The hot conductor (black wire in US wiring convention) connects here. The black wire carries the energised live voltage from the circuit breaker.

2. Silver screws — Neutral: Located on the left side. The neutral conductor (white wire) connects here. Neutral carries the return current to the supply panel's neutral bar at near-zero voltage under normal conditions.

3. Green screw — Protective Earth (Ground): Located at the bottom. The bare copper or green-insulated ground conductor connects here. The ground does not carry operating current — it connects the receptacle's ground pin to the equipment grounding conductor that runs back to the main panel's grounding bus, providing a low-impedance fault return path to trip the breaker in the event of an insulation fault.

In the UK, a standard 13 A BS 1363 socket has three connections: Line (brown wire, 'L' terminal), Neutral (blue wire, 'N' terminal), and Earth (green/yellow wire, 'E' terminal). Always follow the national wiring colour code for your jurisdiction.

Receptacles in a circuit may be wired in two ways. In a 'home run' configuration, only one cable enters the box and connects to the receptacle. In a 'daisy-chain' or 'through wiring' configuration, two cables enter the box — one from the panel (or the previous device) and one feeding the next device. In this case, the hot, neutral, and ground wires are connected in pairs at the receptacle terminals or via wire nuts.

GFCI (Ground Fault Circuit Interrupter) receptacles have additional LINE and LOAD terminals to protect downstream receptacles from ground faults.

All mains electrical work must be performed by a licensed electrician and must comply with applicable codes.

Outlet wiring diagrams vary by region, circuit configuration, and installation type. In the Philippines the standard is 2-pin flat or 3-pin grounded outlets on a 220 V supply, while North American residential outlets run 120 V with a hot, neutral, and ground. Multiple outlets can be wired in parallel by daisy-chaining from the feed outlet, and double duplex receptacles are common for high-demand areas. You can sketch any outlet layout — single, double, or multiple — free in the browser at circuitdiagrammaker.com.

How to wire electrical outlet diagram

Isolate the circuit and verify dead Switch off the circuit breaker protecting the outlet circuit. Verify that the outlet is dead using a plug-in outlet tester or multimeter. Do not rely on the breaker label alone — circuits are sometimes mislabelled. Apply lock-out/tag-out to the breaker before opening the outlet box.
Remove the old outlet and inspect the wiring Remove the cover plate and outlet mounting screws. Pull the outlet carefully from the box. Before disconnecting, photograph the existing wiring arrangement. Check for the number of cables entering the box (single home-run or through-wired daisy-chain). Identify each conductor and verify colours and connections using a multimeter after confirming the circuit is dead.
Prepare the conductors Strip approximately 19 mm (3/4 inch) of insulation from each conductor end if making new connections. Form a J-hook on the stripped end to wrap around the terminal screw shank. Alternatively, use the back-wire (push-in) terminals only if they are listed for the wire gauge — prefer screw terminals for reliability.
Connect the ground wire first Connect the bare copper or green ground wire to the green terminal screw on the outlet. If there are multiple ground wires from a daisy-chain, pigtail them together with a wire nut and run a short pigtail to the outlet's green screw. Tighten the screw firmly so the wire cannot be pulled free.
Connect the neutral wire Connect the white neutral wire to the silver screw (left side, wider slot). In a daisy-chain configuration, pigtail the two white wires together with a wire nut and run a short pigtail to the silver screw. Ensure the wire wraps clockwise around the screw so tightening pulls the wire tighter rather than pushing it off.
Connect the hot wire Connect the black hot wire to the brass screw (right side, narrower slot). In a daisy-chain, pigtail both black wires and connect a pigtail to the brass screw. Tighten all screws to the manufacturer's specified torque (typically 0.9–1.1 N·m for residential outlets).
Install, restore power, and test Fold the wires neatly into the box and push the outlet in. Secure the mounting screws. Install the cover plate. Restore power at the breaker. Use a plug-in outlet tester to verify correct wiring: hot (right slot), neutral (left slot), ground (round hole) all correctly connected and no open or reversed connections. Test GFCI trip and reset function if a GFCI outlet was installed.

Specifications

Standard rating (US residential)	15 A, 125 V AC (NEMA 5-15R) or 20 A, 125 V AC (NEMA 5-20R)
Standard rating (UK)	13 A, 230 V AC (BS 1363)
Terminal colour coding (US)	Brass = hot (black wire); Silver = neutral (white wire); Green = ground (bare or green wire)
Terminal colour coding (UK)	L terminal = brown (live); N terminal = blue (neutral); E terminal = green/yellow (earth)
Wire gauge (US 15 A circuit)	14 AWG (2.08 mm²)
Wire gauge (US 20 A circuit)	12 AWG (3.31 mm²)
GFCI trip threshold	5 mA current imbalance between hot and neutral (UL 943 standard)
Applicable codes	NEC/NFPA 70 (US), BS 7671 (UK), AS/NZS 3000 (AU/NZ), IEC 60364

Safety warnings

Mains electrical work is dangerous and potentially fatal. All outlet installation and wiring work must be performed by a licensed electrician in accordance with NEC/NFPA 70 (USA/Canada), BS 7671 (UK), AS/NZS 3000 (Australia/NZ), or applicable local electrical code. A permit and inspection may be required by your local authority having jurisdiction (AHJ).
Always isolate the circuit at the breaker and verify absence of voltage at the outlet using a calibrated tester before opening the outlet box. Do not rely on a visual check of the breaker position alone.
Never use the 'back-stab' (push-in) terminals on standard (non-listed) outlets with 14 AWG or 12 AWG solid wire — screw terminals provide a far more reliable and code-compliant connection. Loose back-stab connections cause arcing, which is a major cause of electrical fires.
Use the correct outlet ampere rating for the circuit. A 15 A outlet must not be installed on a 20 A circuit unless it is one of multiple outlets on the circuit (as permitted by code). A 20 A circuit feeding a single outlet location requires a 20 A outlet rated for T-slot configuration.
GFCI protection is required by code in specific locations — bathrooms, kitchens, garages, outdoors, unfinished basements, and near sinks. Never replace a GFCI outlet with a standard outlet in these locations. Check current NEC or local code for exact GFCI requirement locations, as requirements are updated in each code cycle.

Tools needed

Non-contact voltage tester
Digital multimeter
Flathead and Pozidrive screwdrivers
Wire strippers (marked for 12 AWG and 14 AWG)
Long-nose pliers (for forming J-hooks)
Plug-in outlet tester
Lockout/tagout device
Flashlight or work light

Common mistakes

Reversed polarity — connecting the black hot wire to the silver (neutral) screw and white wire to the brass screw. This energises the neutral side of connected devices, creating a hidden shock hazard. Always verify polarity with an outlet tester after installation.
Using back-stab (push-in) terminals rather than screw terminals. Push-in connections have higher failure rates and are a source of arcing faults. Use screw terminals exclusively for reliable connections.
Failing to pigtail conductors in daisy-chain boxes, instead looping both wires around a single terminal screw. Most outlet terminal screws are rated for only one conductor — verify the outlet's wiring specifications.
Exceeding the outlet box cubic inch (volume) capacity by adding too many conductors and devices. Code (NEC Article 314.16) specifies minimum box volume based on conductor count and size. Overstuffed boxes are difficult to close, damage wire insulation, and increase fire risk.
Not connecting the ground wire because the old outlet was ungrounded. An ungrounded 3-prong outlet creates a false sense of safety — devices with a ground pin appear grounded but are not. Install a GFCI outlet and label it correctly, or run a ground conductor.

Troubleshooting

Outlet tester shows 'open ground': Cause: Ground wire not connected at outlet, or ground conductor missing from the circuit cable Fix: Shut off circuit, remove outlet, and verify the bare copper or green wire is connected to the green screw. If no ground conductor is present in the circuit, install a GFCI outlet and label it 'No Equipment Ground' per code, or run a ground conductor to the panel.
Outlet tester shows 'reversed polarity': Cause: Hot (black) wire connected to silver screw; neutral (white) wire connected to brass screw Fix: Shut off circuit, remove outlet, and swap the hot and neutral wires to their correct terminals: black to brass, white to silver. Re-test with outlet tester.
GFCI outlet trips immediately on reset: Cause: Ground fault on the load side of the outlet; moisture in the outlet box or a connected device; wiring fault in downstream outlets wired on the LOAD terminals Fix: Disconnect any plugged-in devices and any downstream outlets wired to the LOAD terminals. Reset GFCI — if it holds, the fault is in a connected device or downstream wiring. Inspect downstream wiring for damaged insulation or moisture.
Outlet has no power despite breaker being on: Cause: Tripped GFCI outlet upstream controlling this outlet; loose wire nut in a daisy-chain box; breaker tripped without visual indicator Fix: Check if there is a GFCI outlet elsewhere on the same circuit — press RESET on any GFCI outlet in the area. If no GFCI, check all wire nut connections in the upstream outlet box. Confirm breaker is fully on (reset by switching fully off then on).
Outlet is loose or rocks in the wall: Cause: Mounting screws not tightened; oversized box relative to drywall opening; worn outlet mounting slots Fix: Tighten the outlet mounting screws. If the box is recessed, use box extenders or outlet shims. Replace the outlet if the mounting tabs are stripped.

Frequently asked questions

What colour are the hot, neutral, and ground wires in a standard outlet circuit?

In US/Canadian residential wiring: black = hot (Line), white = neutral, bare copper or green = ground. In UK wiring: brown = Line (hot), blue = neutral, green/yellow stripe = earth. In Australia: red or brown = active (hot), black or blue = neutral, green/yellow = earth. Always verify using a voltage tester — never rely solely on colour if working on older wiring.

Which side of a US outlet do I connect the hot wire to?

The hot (black) wire connects to the brass (gold-coloured) terminal screw, located on the right side when the outlet face is toward you. The wider neutral slot is on the left, connecting to the silver screw. A memory aid: 'Brass for Black, Silver for White.' Reversing these creates a shock hazard — the neutral prong of a plug would then be energised.

What is the difference between a GFCI outlet and a standard outlet?

A GFCI (Ground Fault Circuit Interrupter) outlet monitors the current balance between the hot and neutral conductors. If a difference of approximately 5 mA or greater is detected — indicating current is leaking through a person or to ground — the GFCI trips within milliseconds, cutting power. GFCI protection is required by code near water sources (kitchens, bathrooms, outdoors, garages) in most jurisdictions.

Can I wire an outlet without a ground wire?

Technically you can — a 2-wire outlet (no ground) is permitted in older ungrounded circuits under some codes as a replacement, but a 3-prong receptacle must not be installed in an ungrounded box without providing GFCI protection and labelling it 'No Equipment Ground'. The preferred and safest solution is to run a grounding conductor to the panel or install a GFCI outlet and label it correctly per NEC Article 406.4.

What causes an outlet to have power on the neutral terminal (hot neutral)?

A reversed polarity connection — the hot wire is connected to the silver (neutral) screw and the white neutral wire to the brass (hot) screw. This is a dangerous wiring fault: the device connected to the outlet is energised at mains voltage on what appears to be the neutral side. Always verify polarity with an outlet tester or multimeter after installation.

How do I draw an electrical wiring diagram for an outlet?

Connect the black (hot) wire to the brass screw, the white (neutral) wire to the silver screw, and the bare or green ground wire to the green screw on the outlet. In a diagram, draw the supply conductors entering the box, the outlet symbol, and label each terminal. If the outlet feeds another, show a continuation of all three conductors from the outlet to the next device.

What is the standard electrical outlet wiring diagram in the Philippines?

Philippine residential wiring uses 220 V single-phase with a live, neutral, and ground. Outlets follow PEC (Philippine Electrical Code) requirements; standard receptacles are Type A or Type B (flat-pin) rated at 220 V 15 A or 20 A. The live wire connects to the right terminal, neutral to the left, and ground to the top round pin. Always verify with a licensed Filipino electrician as local code amendments apply.

How do you wire multiple electrical outlets on one circuit?

Multiple outlets on one circuit are wired in parallel: the hot, neutral, and ground from the panel feed the first outlet, then short pigtail or pass-through wires carry those three conductors to each subsequent outlet. Each outlet shares the same 120 V (or local equivalent) across its terminals. Ensure the total load does not exceed the circuit breaker rating — typically 15 A or 20 A for a residential branch circuit.

What does a wall outlet wiring diagram show?

A wall outlet wiring diagram shows the incoming supply cable entering the electrical box, the hot conductor (black in North America) terminating at the brass terminal, the neutral (white) at the silver terminal, and the ground (bare copper or green) at the green terminal. It may also show cable clamps, the box ground, and any continuation wiring to the next outlet downstream.

How do you wire a double electrical outlet?

A double duplex outlet (two receptacles on one yoke) is wired the same way as a single: hot to brass, neutral to silver, ground to green. The two receptacles share the same hot and neutral unless a break-off tab is removed, which allows each receptacle to be on a separate circuit (split-wired). Split wiring requires two-pole breaker protection or separate breakers with handle ties per code.

What does a residential electrical outlet wiring diagram look like?

A residential outlet wiring diagram typically shows a 15 A or 20 A duplex receptacle fed from a 15 A or 20 A breaker in the panel. It includes the hot, neutral, and equipment ground conductors, the outlet symbol, and any downstream daisy-chain connections. AFCI or GFCI protection requirements depend on room location per the NEC; bedrooms and wet areas have additional protection requirements.