Electric Shock Triage Guideline: Hospital Referral and ECG

Draft v0.1, 9 November 2026.

Reviewed and endorsed by

Dr Alana Bond FACEM Emergency Physician, Dr Tim Harraway FACEM Emergency Physician and Dr Jon Field FACEM, FCICM Intensive Care and Emergency Physician

This guideline sets out who should be sent to hospital, and who needs an ECG, after an electric shock reported to the triage call centre. It replaces the blanket rule that every shock needs an ED ECG with a risk-based approach that matches the evidence. It separates trivial exposures (static discharge, extra-low voltage, brief mains tingles in well people) from exposures that warrant cardiac assessment.

Summary

This guideline recommends an ECG only for mains-level or unknown-voltage exposures with a defined risk feature, and no hospital attendance for trivial exposures in well people with safety-net advice.

Triage tiers

Tier 1: Ambulance (000)

• Loss of consciousness, collapse, seizure or cardiac arrest
• Ongoing chest pain, palpitations, breathlessness, new confusion or new weakness
• High voltage (over 1000 V, such as power lines, substations and rail) or lightning
• Significant burns, or a fall or trauma associated with the event
• A child with an oral burn from biting or sucking a live cord

Tier 2: Same-day ED attendance for ECG

Mains-level source (230/240 V AC, 415 V three-phase) or unknown voltage, plus any one of the following:

• Brief loss of consciousness, near-syncope or a "funny turn" at the time, or any residual symptom
• Current passing through the chest (hand to hand, or contact at the head or chest), prolonged contact, or tetany (unable to let go)
• Visible entry or exit burn or skin mark
• Wet conditions or immersion
• Known heart disease, pacemaker or ICD, antiarrhythmic medication, or family history of sudden cardiac death
• Pregnancy

The patient should be driven by someone else and should not drive. The aim is an ECG.

Tier 3: No hospital attendance, with safety-net advice

All of the following apply:

• Source is extra-low voltage (50 V AC or less, or 120 V DC or less, such as 12 V vehicle or battery systems), static discharge, or a brief mains "tingle" or zap
• No loss of consciousness and no current symptoms
• No burn or skin mark
• Single-limb contact, with no current path through the chest
• No cardiac history or implanted device, and not pregnant

Young, well patients fall in this tier by default. Age alone is not a trigger. Static discharge and extra-low voltage sources are well below any plausible threshold for ventricular fibrillation in a structurally normal heart (this is physiological reasoning, not a study finding). A person with an implanted cardiac device is handled in Tier 2 regardless of source.

Call-centre question set

1. What was the source: mains, battery, static or unknown? Were conditions wet?
2. Did the person collapse, black out or feel faint? Did they fall?
3. Where did the current enter and leave the body, and could they let go?
4. Are there any symptoms now: chest pain, palpitations, breathlessness, dizziness, tingling or weakness?
5. Is there any burn or skin mark, including in the mouth?
6. Is there a heart condition, pacemaker or ICD, or cardiac medication? Is the person pregnant?
7. What is the person's age?

Any Tier 1 answer means 000. Any Tier 2 trigger with a mains-level or unknown source means ED for ECG. Otherwise Tier 3. Document the answers for every call.

Safety-net advice for Tier 3

Seek urgent care if palpitations, fainting, chest pain, breathlessness, or new numbness or weakness develop, particularly in the next 24 to 48 hours. Report the incident to the employer under the usual workplace incident process.

Determining whether the source is mains-level

The call centre cannot measure voltage, so the source is inferred from what the person touched and how it was powered. Assume mains-level unless the source is clearly low voltage. If the source cannot be established, classify it as unknown voltage and manage it as mains-level.

Ask in this order:

1. What exactly did you touch? Record the object or equipment (power point, appliance, power tool, extension lead, switchboard, vehicle, charger, machinery).
2. Was it plugged into a wall socket, hardwired into the building or machine, or running on a battery? A wall socket or hardwired connection means mains. A three-pin plug is 230/240 V AC.
3. Was it switched on or connected at the time? Confirm the source is now isolated.
4. If it was battery powered, what type? A car or caravan 12 V battery, a 12 V or 24 V accessory, or a cordless tool pack (about 18 to 36 V) is extra-low voltage. Solar panels, home batteries, electric vehicles, forklifts and UPS units can carry hundreds of volts DC, so classify them as unknown or high voltage. Ask whether anything was plugged into an inverter, because inverter output is 240 V.
5. Is it industrial or three-phase equipment, such as a switchboard, distribution board, motor, welder, large machinery, commercial kitchen equipment or a caravan park pedestal? Treat it as 415 V or higher. Ask whether an electrician or maintenance person on site can confirm.
6. Can someone safely read the rating plate or label (for example 230 V~, 240 V, 415 V or 12 V DC)?
7. Was there a visible spark, flash, bang or burn mark, or did the safety switch (RCD) trip? These point to mains-level or arc involvement. Arc flash from a switchboard is a burn problem and goes to Tier 1 or 2 regardless of voltage.
8. What did it feel like? A grip, being unable to let go, or being thrown makes mains-level or higher more likely. A brief tingle does not rule mains out, because mains tingles and static can feel alike.
9. For possible static: was there no cable or appliance involved, in dry conditions, with carpet, a car door, clothing or a trolley, and a brief spark or snap with no sustained contact? If any cable, appliance or wall socket was involved, it is not static.

Classify the source as follows:

• Mains (230/240 V): wall socket, hardwired supply, extension lead or mains appliance.
• 415 V or higher: industrial equipment, switchboard, motor or welder.
• Unknown or high voltage: solar array, electric vehicle, home or industrial battery, inverter output, or any source that cannot be identified. Manage as mains-level.
• Extra-low voltage: car battery, 12 V or 24 V accessory, or cordless tool pack.
• Static: no cable involved, dry conditions and a brief spark.

A mains-powered charger or appliance that gives a brief tingle is still a mains source. Do not classify it as extra-low voltage because the device output is 5 V. If there are no Tier 2 features, a brief mains tingle is managed under Tier 3. Ask about wet conditions early, because wet conditions with a mains-level source are a Tier 2 trigger.

Evidence summary

• Low-voltage injuries with a normal ECG. A prospective three-year audit of 212 presentations to Mount Isa Base Hospital found early transient conduction abnormalities in 4% of patients. Admissions for monitoring fell sharply after a protocol change, with no adverse effects. The authors concluded asymptomatic patients with a normal presenting ECG need no monitoring (Blackwell and Hayllar, Postgrad Med J 2002).
• Higher-risk features. In a 21-centre Canadian study of 134 patients with theoretical risk factors (transthoracic current, tetany, loss of consciousness or voltage of 1000 V or more), asymptomatic patients with transthoracic current and/or tetany and a normal initial ECG did not need monitoring if the voltage was under 1000 V and there was no loss of consciousness (Bailey et al., Emerg Med J 2007).
• Delayed arrhythmia. A 2023 systematic review of low-voltage electrical injuries found no case of delayed arrhythmia in the included studies. It noted that the data are limited and that arrhythmias in this group seldom need intervention (Corrall et al., Br Paramed J 2023). A separate cohort of 333 patients (reference 6), about a third of them children, found all malignant arrhythmias occurred immediately after the injury and that delayed life-threatening arrhythmias were not observed. Its authors concluded that asymptomatic, uninjured adults and children with a normal initial ECG do not need continuous monitoring.
• Timing of risk. The risk of malignant arrhythmia is greatest at the time of injury. The incidence of late arrhythmia is unknown but thought to be very low (RCEM Learning).
• Existing guideline anchor. As summarised in the Budapest cohort paper (reference 5), the European Resuscitation Council recommends ECG monitoring after electrical accident for people with known cardiorespiratory disease, or with loss of consciousness, initial cardiac arrest, soft tissue damage or burns, or an abnormal ECG on arrival. The same paper notes this rests on a few mostly retrospective studies and case reports.

Limits of the evidence

• All studies are observational. There are no randomised trials.
• Every study enrolled people who had already presented to hospital and had an ECG. None tested withholding the ECG from low-risk people, so the evidence shows a normal ECG makes discharge safe but does not prove that skipping the ECG is safe.
• Tier 3 is therefore a reasoned extrapolation based on the very low pre-test probability in trivial exposures. It is not a validated decision rule.
• Evidence on pregnancy is limited to case-level reports, so Tier 2 for pregnancy is a cautious default.

Employer position

• Sending every shock to ED for an ECG is not supported by the literature. The evidence supports risk stratification.
• In the studies reviewed, a normal ECG in an asymptomatic person was followed by safe discharge, with no delayed arrhythmias reported.
• Each Tier 3 call is documented against the question set, giving the employer a defensible record.

References

1. Bailey B, Gaudreault P, Thivierge RL. Cardiac monitoring of high-risk patients after an electrical injury: a prospective multicentre study. Emerg Med J 2007;24:348-52. <https://pmc.ncbi.nlm.nih.gov/articles/PMC2658483>
2. Blackwell N, Hayllar J. A three year prospective audit of 212 presentations to the emergency department after electrical injury with a management protocol. Postgrad Med J 2002;78:283-5. <https://dora.health.qld.gov.au/qldresearchjspui/handle/1/5446>
3. Wilson CM, Fatovich DM. Do children need to be monitored after electric shocks? J Paediatr Child Health 1998;34:474-6. <https://research-repository.uwa.edu.au/en/publications/do-children-need-to-be-monitored-after-electric-shocks/>
4. Corrall S, Laws S, Rice A. Low-voltage electrical injuries and the electrocardiogram: is a "normal" electrocardiogram sufficient for safe discharge from care? A systematic review. Br Paramed J 2023;8(3):27-36. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10690487/>
5. Hungarian Defence Forces Medical Centre cohort. Arrhythmias and ECG abnormalities after electrical accident. Clin Res Cardiol 2019. <https://link.springer.com/article/10.1007/s00392-019-01420-2>
6. Arrhythmias and laboratory abnormalities after an electrical accident, 333-case cohort. <https://www.springermedizin.de/arrhythmias-and-laboratory-abnormalities-after-an-electrical-acc/25874600>
7. RCEM Learning. The management of electrical injuries: patient monitoring. <https://www.rcemlearning.co.uk/modules/electrical-burns-in-the-ed/lessons/the-management-of-electrical-injuries/topic/patient-monitoring/>