Customer Says They Got A Shock, Translation To Real Fault Decision Tree

Why this matters

A reported shock is never a nuisance call. It means current found a path through a person, and that path exists because a normally-dead surface became energized: an open or missing ground, a hot-to-ground reversal, a ground-fault on an appliance frame, a bonding failure, or stray voltage on metallic water/gas piping. The verbal complaint ("I got a shock off the dryer," "the faucet bites me") translates to a specific fault that must be found and cleared, not just reassured away. Treating it as a one-off risks a fatal repeat. The discipline is to verify the shock source is de-energized or GFCI-protected before anyone touches it again, then methodically measure where the unwanted voltage is and how it is getting to a touchable surface.

Symptom presentation

The customer reports a tingle or jolt from a normally safe object: an appliance case (dryer, washer, range, fridge), a metal faucet or sink, a light fixture or switch plate, a pool or spa surface, or a metal door frame. Useful detail: the shock happens when they are also touching something grounded (a faucet, a wet floor, plumbing), happens only when the appliance runs, or is worse when barefoot or wet. A shock that requires touching two surfaces at once points to a voltage difference between them (a bonding or stray-voltage problem); a shock from one object alone points to that object being energized with a missing safe ground.

Quick checks

• Establish urgency: if the source is a major appliance or wet location, advise the customer to stop using it until cleared.
• With a meter, measure the suspect surface to a known good ground (a verified grounding electrode or a confirmed ground): any significant voltage there is the fault.
• Measure the suspect surface to the neutral and to building ground separately to see which reference shows the difference.
• At the feeding receptacle, use a tester and meter to check for an open ground, reversed hot/ground, or a bootleg ground (neutral tied to ground at the device).
• Check whether the circuit is GFCI-protected and whether the appliance case is properly bonded to equipment ground.

Isolation tree

1. Suspect surface reads near line voltage (around 120 V) to a known good ground? The surface is energized. A hot conductor or component is contacting the frame and there is no effective equipment-grounding path to clear it. Find the internal fault and the missing/open ground.
2. Surface reads a partial voltage (tens of volts) to ground that varies with load? Stray or induced voltage, often from a high-resistance neutral, a shared neutral leaking, or capacitive/inductive coupling on an ungrounded run. Trace the leakage source.
3. Receptacle tester shows open ground? The equipment-grounding conductor is broken or never connected, so a fault on the appliance cannot trip the breaker and instead energizes the case. Restore the ground.
4. Tester shows hot/ground reversed or a bootleg ground (neutral and ground bonded at the device)? The grounding system is mis-wired so the "ground" carries current or is at the wrong potential. Correct the wiring.
5. Shock only when touching the object and a plumbing fixture simultaneously? Voltage difference between systems: a bonding failure between the electrical ground and the metallic water/gas piping, or stray voltage on the piping. Verify and restore bonding.
6. Pool, spa, or wet location involved? Treat as a bonding/equipotential-grid problem and a high-hazard condition; the bonding grid or a fault is the likely cause.

Confirming diagnosis

Confirm an energized frame by metering case-to-ground with the appliance off and on: a fault that appears only when running points to internal insulation breakdown under load. Confirm the grounding path by measuring continuity from the appliance case back to the panel ground bar (de-energized): an open reading proves the missing ground that let the case energize. Confirm wiring faults at the receptacle with a meter, distinguishing a true open ground from a bootleg ground (a bootleg shows near-0 V ground-to-neutral but carries current). For stray voltage between systems, measure the potential difference between the electrical equipment ground and the water/gas pipe; a real difference confirms a bonding gap. A GFCI that trips when you energize the suspect circuit corroborates a ground-fault leakage path.

Remediation

Energized frame with internal fault: repair or replace the appliance causing the hot-to-case contact, and restore the equipment-grounding path so any future fault trips the breaker. Open or missing ground: re-establish the equipment-grounding conductor end to end, or add the required ground; on legacy ungrounded circuits, provide GFCI protection and label per code where a true ground cannot be run. Reversed or bootleg ground: rewire the device to correct polarity and separate ground from neutral (neutrals and grounds bond only at the service). Bonding failure between systems: restore bonding of metallic water and gas piping to the grounding electrode system. Stray voltage from a high-resistance neutral: repair the neutral. Pool/spa: restore the equipotential bonding grid and clear the fault. After any repair, re-measure the surface to ground (near 0 V), verify the grounding path, and confirm GFCI operation where required.

References

• National Electrical Code (NFPA 70), Article 250, Grounding and Bonding.
• NEC Article 250.114, Equipment That Is Required to Be Grounded.
• NEC Article 406.4(D), Replacements (GFCI protection for non-grounding receptacle replacements).
• NEC Article 680, Swimming Pools, Fountains, and Similar Installations (equipotential bonding).
• NFPA 70E, Standard for Electrical Safety in the Workplace.