What are the basic steps to diagnose a single dead outlet when the rest of the circuit works?

Short answer

Start by checking for a tripped GFCI or breaker, verify the outlet isn’t controlled by a wall switch (half‑hot), and test for power with a plug-in tester or non-contact voltage tester. If power is present at the box but the outlet is dead, replace the receptacle. If there’s no power at the outlet, open the last working and first dead outlets on the circuit to find a loose connection—often a failed backstab—then repair with proper pigtails and wirenuts/lever connectors. Always turn off the breaker and verify power is off before opening boxes.

Why a single outlet can be dead while others work

Most homes use daisy-chained receptacles. A single bad device or loose connection (commonly at the last working receptacle or the dead one) can open the hot or neutral path downstream. Other common causes:
- A tripped upstream GFCI (bath, kitchen, garage, exterior, basement) protecting downstream outlets
- A half-switched receptacle (top or bottom controlled by a wall switch)
- A tripped AFCI breaker or combination GFCI/AFCI
- Damaged receptacle, burned stab connection, or loose wirenut
- Miswired GFCI (line/load reversed)

Tools and materials

• Non-contact voltage tester (NCVT)
• Plug-in outlet tester (three-light) and/or a multimeter
• Flashlight/headlamp
• Insulated screwdrivers
• Needle-nose pliers, wire strippers
• UL-listed wirenuts or lever connectors (e.g., Wago)
• 15A or 20A replacement receptacle (match circuit and wire size), GFCI if replacing a protected first-in-line
• Electrical tape and labels

Time and cost: 15–60 minutes. $20–$60 in basic tools and parts (tester $10–$20, NCVT $15–$25, receptacle $2–$5, GFCI $15–$25).

Step-by-step diagnosis

1. Safety first

   • Turn off and unplug anything in the dead outlet. If you’ll open a box, switch off the breaker and verify with your tester. Wear eye protection.

2. Quick checks

   • Try a known-good lamp or device at the dead outlet to rule out a bad plug/device.
   • Check the breaker panel. Reset any tripped breakers (firmly OFF, then ON). Look for AFCI/GFCI breakers with indicator lights.
   • Hunt for tripped GFCIs: press RESET on all GFCI outlets in bathrooms, kitchen, garage, basement, exterior, laundry. One tripped GFCI can kill multiple downstream outlets.

3. Is it a half-switched outlet?

   • Plug a lamp into top and bottom. Toggle nearby wall switches. If one half works only with a switch, the receptacle is split (tab removed). If both halves are dead unless a certain switch is on, you’ve found the cause.

4. Test for voltage at the dead outlet

   • With power ON and caution, use a NCVT at the hot slot (shorter slot). If it doesn’t beep, hot may be open or upstream GFCI tripped.
   • A plug-in outlet tester can show open hot/neutral/ground patterns. Be aware these testers can’t detect all faults (e.g., bootleg grounds).
   • With a multimeter (if comfortable): Hot (narrow slot) to Neutral (wide slot): ~120 VAC Hot to Ground (U-shaped): ~120 VAC Neutral to Ground: ~0 VAC
     • ~120V hot-to-ground but 0V hot-to-neutral = likely open neutral.
     • 0V on all = open hot or tripped upstream device.

5. Identify the fault location (upstream vs. at the outlet)

   • Map the run: find the last working outlet on the circuit and the first dead one. Problems are often in one of these two boxes.
   • Turn OFF the breaker. Pull the dead outlet from the box. Inspect for:
     • Backstabbed wires (pushed into spring holes) — these often fail
     • Loose wirenuts, charred insulation, broken tab on the wrong side
     • Red or switched wire indicating a split receptacle
   • If the dead outlet looks fine, open the last working outlet and check the pass-through connections. A loose connection here can kill the next outlet.

6. Make solid repairs

   • Replace any backstab connections with screw terminals and pigtails:
     • Join feed and onward conductors with a wirenut/lever connector and a short pigtail to the receptacle hot; do the same for neutral and ground.
   • If replacing the device, match ratings:
     • 15A receptacle for 15A circuit with 14 AWG wire
     • 15A or 20A receptacle for 20A circuit with 12 AWG wire (do not put a 20A receptacle on a 15A circuit)
   • For split/switched outlets, ensure the correct side tab is removed (hot side only) and conductors return to their original locations.
   • Reassemble, restore power, and retest.

Safety considerations

• Always de-energize and verify before handling conductors.
• Aluminum wiring, overheated/charred parts, or brittle insulation warrant a licensed electrician.
• On multi-wire branch circuits (shared neutral with red/black hots), neutrals must stay continuous and breakers must be handle-tied/two-pole. If you see red and black hots with a shared neutral, call a pro if you’re unsure.

Tips for best results

• Label the breaker once you find it. Consider a small map of GFCI-protected outlets.
• Upgrade old receptacles when you’re there; tamper-resistant devices are usually $2–$5 more.
• Use pigtails rather than landing multiple wires under one screw. Avoid backstabs.
• In kitchens, baths, garage, exterior, unfinished basements, use GFCI protection as required by code.

Common mistakes

• Replacing the dead receptacle without fixing a loose upstream connection.
• Miswiring GFCI line/load; this will leave downstream outlets dead. The incoming feed goes to LINE.
• Mixing wire sizes or installing a 20A receptacle on a 15A circuit.
• Failing to fully reset a tripped breaker (must click OFF first, then ON).

When to call a professional

• Scorched/melted insulation or repeated tripping
• Aluminum branch wiring, knob-and-tube, or uncertain wiring methods
• Evidence of a multi-wire branch circuit you’re not comfortable with
• No ground present where required and you need GFCI or grounding upgrades

With a tester, a screwdriver, and careful inspection, most single dead-outlet issues can be found and fixed in under an hour. The most frequent culprit: a loose backstab or a tripped upstream GFCI.