An outlet to outlet wiring diagram (commonly referred to as daisy-chaining) routes 120V AC power from a breaker panel to the first receptacle's LINE terminals, then jumps from its LOAD terminals to the next receptacle, sharing a single branch circuit. For a standard 15A branch circuit, this requires 14 AWG NM-B cable protected by a 15A breaker; for a 20A circuit, you must use 12 AWG NM-B and a 20A breaker. This guide provides a literal node-by-node trace of the circuit path, maps the physical device terminals, and details exactly how to verify your work with a multimeter before energizing the system.

Decoding the Diagram: NEC Symbols and Physical Device Mapping

Before tracing the physical wires, you must translate the schematic symbols used in standard National Electrical Code (NEC) compliant drawings to the physical hardware on your workbench.

  • Receptacle Symbol: A circle with two parallel slits extending from it represents a standard duplex receptacle. If the circle has the letters 'GFCI' or 'GF' inside, it denotes a Ground Fault Circuit Interrupter.
  • Ungrounded Conductor (Hot): Represented by a solid black line on the diagram. Physically, this is the black wire in NM-B cable, which terminates on the brass-colored screws on the receptacle.
  • Grounded Conductor (Neutral): Represented by a dashed or white line. Physically, this is the white wire, terminating on the silver-colored screws.
  • Equipment Grounding Conductor: Represented by a green line or a line with standard ground symbols (three decreasing horizontal lines). Physically, this is the bare copper wire, terminating on the green grounding screw.
Bench Tip: Always identify the LINE vs. LOAD terminals on the physical device. On standard receptacles (like the Leviton 5262), the top and bottom screw pairs are internally bridged by a break-off brass tab. The side where the power enters from the panel is your LINE; the side where power exits to the next outlet is your LOAD.

Node-by-Node Trace: Source to Load Path

Follow this exact sequence to trace the current path from the overcurrent protective device to the final outlet in the run.

  1. Node 1: The Panel (Source). The black (hot) wire from your 14/2 or 12/2 NM-B cable lands on the terminal of a 15A or 20A single-pole breaker. The white (neutral) wire lands on the neutral bar. The bare copper (ground) lands on the equipment grounding bar. Safety check: Ensure the main breaker is OFF and test for dead before touching any bus bars.
  2. Node 2: Cable 1 (The Line Run). The cable travels through the framing to the first outlet box. You strip back 3/4 inch of insulation from the black and white wires, and leave 3/4 inch of bare copper exposed on the ground wire.
  3. Node 3: Outlet 1 (The Junction). The incoming black wire loops clockwise around the top brass screw (LINE). The incoming white wire loops clockwise around the top silver screw (LINE). The incoming bare copper loops around the green grounding screw.
  4. Node 4: The Jumper (The Load Run). A second piece of NM-B cable enters the box to feed the next outlet. The outgoing black wire lands on the bottom brass screw (LOAD). The outgoing white wire lands on the bottom silver screw (LOAD).
  5. Node 5: The Ground Pigtail. Because NEC 250.148 requires that the grounding path remain continuous even if a device is removed, you cannot simply loop the ground wire from one screw to the next. You must use a wire nut to join the incoming bare ground, the outgoing bare ground, and a 6-inch bare copper 'pigtail' that lands on the receptacle's green screw.
  6. Node 6: Outlet 2 (End of Run). The cable from Node 4 enters the second box. The black wire lands on a brass screw, the white wire on a silver screw, and the bare ground on the green screw. Because this is the end of the run, the LOAD terminals remain empty, and you do not break off the connecting fins on the brass or silver tabs.

Terminal and Pin Mapping Specification Table

Use this reference sheet when terminating standard 15A and 20A duplex receptacles. Torque specifications are critical; under-torqued terminals cause high-resistance connections that lead to arcing and melted faceplates over time.

Terminal Color Function Wire Color (US NEC) AWG Size (15A / 20A) Torque Spec (Typical) Connection Method
Brass Ungrounded (Hot) Black 14 AWG / 12 AWG 14 in-lbs Screw terminal (side wire)
Silver Grounded (Neutral) White 14 AWG / 12 AWG 14 in-lbs Screw terminal (side wire)
Green Equipment Ground Bare / Green 14 AWG / 12 AWG 14 in-lbs Screw terminal via pigtail
Backstab (Push-in) Line/Load (15A only) Black / White 14 AWG ONLY N/A (Spring loaded) Avoid: Prone to failure

Note: Torque values are based on standard manufacturer specs (e.g., Pass & Seymour, Leviton) for #10-32 or #8-32 terminal screws. Always verify against the spec sheet included in the device box, as mandated by OSHA and NEC 110.14(D).

Verifying Your Connections with a Multimeter

Never energize a newly wired circuit without performing a two-stage verification. You will need a True-RMS digital multimeter (like a Fluke 117) and a non-contact voltage tester.

Stage 1: De-energized Continuity Check

  1. Keep the breaker OFF.
  2. Set your multimeter to Continuity (the diode/sound wave symbol).
  3. Place one probe on the bare ground wire at the panel and the other probe on the green grounding screw at Outlet 2. You should read less than 1.0 ohm (or hear a continuous beep), confirming an unbroken equipment grounding path.
  4. Check for dead shorts: Place one probe on the brass (hot) terminal and the other on the silver (neutral) terminal at Outlet 2. The meter should read 'OL' (Open Line). If it reads near zero ohms, you have a hot-to-neutral short that will trip the breaker instantly.

Stage 2: Energized Voltage Check

  1. Turn the breaker ON.
  2. Set the multimeter to AC Voltage (V~).
  3. Insert the black probe into the ground slot (U-shape) and the red probe into the hot slot (the shorter vertical slot). You should read between 114V and 126V.
  4. Move the red probe to the neutral slot (the longer vertical slot). You should read less than 2V. A reading higher than 5V indicates a high-resistance neutral connection or an open neutral upstream.

Frequently Asked Questions

How do I read an outlet to outlet wiring diagram when the first device is a GFCI?

When a Ground Fault Circuit Interrupter (GFCI) is the first device in a daisy chain, the wiring diagram changes slightly at Node 3. The incoming power from the panel must land on the terminals explicitly marked 'LINE' on the back of the GFCI. The outgoing cable feeding the downstream standard outlets must land on the terminals marked 'LOAD'. If you reverse these, the GFCI will power itself but will not provide ground-fault protection to the downstream outlets, and the 'TEST' button will not trip the circuit. Furthermore, downstream outlets wired to the LOAD terminals will trip off if the GFCI detects a fault, which is the intended behavior for protecting multiple nodes on a single branch.

Can I use an outlet to outlet wiring diagram for a 20-amp kitchen small-appliance circuit?

Yes, but with strict material constraints. NEC 210.52 requires at least two 20-amp small-appliance branch circuits for kitchen countertops. When wiring outlet to outlet on these circuits, you must use 12 AWG copper wire and 20-amp rated receptacles (identified by the T-shaped neutral slot on the faceplate). You cannot use 15-amp receptacles on a 20-amp breaker unless they are part of a multi-outlet branch circuit, but using 20-amp rated devices throughout is the safest, most code-compliant practice for kitchen environments where high-draw appliances like microwaves and air fryers are common.

Why do professional outlet to outlet wiring diagrams show pigtails for the ground wire instead of a pass-through loop?

While it is physically possible to loop a single ground wire onto the green screw and continue it to the next box, NEC 250.148 strictly requires that the grounding continuity remain intact even if the receptacle is removed for replacement. If you use a pass-through loop on the hot or neutral wires and someone removes the outlet, the downstream outlets lose power (which is obvious and annoying). If you use a pass-through loop on the ground wire and someone removes the outlet, the downstream outlets lose their safety ground while remaining powered—a lethal, invisible hazard. Pigtailing the ground (and best practice dictates pigtailing the hot and neutral as well) ensures that removing the device does not break the circuit path for downstream nodes.