No Power: Which to Check First, Breaker vs Device vs Wire

Why this matters

A "no power" call wastes the most labor when the tech chases the wrong layer. Power can stop at the source (breaker or panel bus), at the conductor run (open splice, broken backstab, damaged cable), or at the device (failed receptacle, switch, or fixture). Starting at the wrong end means pulling devices that test fine while the real open sits two boxes upstream. A disciplined source-to-load sequence finds the break in one pass and keeps you from energizing a fault you have not located.

Symptom presentation

The customer reports one or more dead outlets, a dead room, or a dead lighting circuit. The breaker may look ON, may be tripped, or may sit in the ambiguous center position. Other circuits work normally. There may be a recent trigger: a tripped GFCI, a remodel, a new device install, or a storm. The pattern of what is dead versus alive is your first map of where the open lives.

Quick checks

Before opening anything, gather data from the load side:

• Plug a known-good tester or lamp into every dead outlet and note which are dead and which still work. The boundary between live and dead points at the open.
• Press RESET on every accessible GFCI, including bathrooms, garage, exterior, and kitchen. A tripped upstream GFCI kills all downstream feed-through receptacles and is the single most common "dead outlet" cause.
• Check whether the dead items share a wall switch. A switched receptacle with the switch off reads dead and is not a fault.
• At the panel, read the breaker for that circuit. Cycle it fully OFF then ON; a tripped breaker can sit mid-travel and look closed.
• Use a meter, not just a neon or plug-in tester, on dead points. A solenoid or non-contact tester can show phantom voltage on a capacitively coupled open conductor and send you chasing a circuit that is actually dead. A loaded reading (meter plus a known load) tells the truth.

Mapping the live/dead boundary first is what makes the rest of the call fast. If half a room is dead and half is live, the open is at the last live box; you start there instead of at the panel. If an entire multi-room circuit is dead, start at the panel. If only one device is dead while everything downstream of it still works, the fault is at that device or its feed-through tap.

Isolation tree

Work source to load. At each node, a voltage reading decides the branch.

1. Breaker output. With the cover off and the panel energized, meter from the breaker load terminal to neutral bar. Expect about 120 V on a single-pole circuit.
   • No voltage at the breaker terminal: the breaker is tripped, failed internally, or loose on the bus. Cycle it; if still dead, swap to a known-good breaker in another slot to confirm.
   • 120 V present: the source is good. The open is downstream. Go to step 2.
2. First box on the run. Identify the first device fed by the circuit (often nearest the panel). Read line-side terminals.
   • 120 V at the line side: feed into this box is good; continue downstream.
   • 0 V: the open is between the panel and this box, or at an upstream GFCI feed-through. Re-check GFCIs, then inspect the upstream splice.
3. Walk the chain device by device. At each box, read both line and load terminals. The first box that shows voltage on line but not on load contains the open: a failed device, a burned backstab, a loose screw, or a broken pigtail. Read line-to-neutral and line-to-ground at each point; if line-to-ground is 120 V but line-to-neutral is low or zero, the open is on the neutral side, not the hot. Backstab terminations are the most frequent break: the spring loses tension under heat cycling and the conductor backs out enough to open while still looking seated.
4. Neutral path. If every hot reads 120 V to ground but loads still will not run, test hot to neutral. A reading near 0 V with 120 V hot-to-ground means an open neutral upstream. Track the neutral splices the same way, box by box, line to load. An open neutral on a shared/multiwire circuit can also place 240 V across two 120 V loads in series, so confirm nothing was damaged before re-energizing.
5. Box without the conductor at all. If a box reads dead on line, load, and neutral with no other circuit present, the feed cable itself may be cut, abandoned, or never landed - common after a remodel where a wall was opened. Trace the cable physically; the homeowner's recent work names the spot.

Confirming diagnosis

You have the fault when voltage is present on the supply side of one connection and absent on the load side of that same connection, with the conductor continuous. Confirm by:

• Re-reading after a slight tug or wiggle of the suspect conductor. A reading that flickers between 0 and 120 V is a loose or arcing connection, not a clean break.
• De-energizing and ohming the suspect segment. Continuity confirms the conductor; an open reading confirms a broken splice or conductor.
• Verifying device function in isolation: pull the receptacle, jumper a known-good one in its place, and confirm the box now feeds downstream.

Remediation

• Breaker fault: replace with a like-rated breaker listed for the panel. Torque the bus and load lugs to the marked value. A breaker that trips again on a clean circuit signals a downstream fault, not a bad breaker.
• Open conductor or splice: remake the connection with the correct connector for the conductor count and material. Replace any backstabbed device connection with a side-screw termination or pigtail; backstabs are the dominant failure point on these calls.
• Failed device: replace the receptacle or switch. Inspect for heat damage that signals an undersized or loose termination, and correct the cause, not just the device.
• After repair, re-energize and verify 120 V at every previously dead point, then confirm neutral integrity hot-to-neutral.

References

• NFPA 70 (NEC) Article 110 - General requirements for examination, identification, and installation of conductors and connections.
• NFPA 70 (NEC) Article 210 - Branch circuits, including receptacle and conductor requirements.
• NFPA 70 (NEC) Article 406 - Receptacles, cord connectors, and attachment plugs.
• NFPA 70E - Standard for Electrical Safety in the Workplace, energized work and PPE selection.
• NFPA 70B - Recommended Practice for Electrical Equipment Maintenance, connection and termination inspection.