FIRST AID GUIDE

Electric Shock First Aid UK: What to Do — and What Not to Do

Life-critical guide to electric shock first aid in the UK. The most important rule: do NOT touch the casualty while they are in contact with the source. Isolate the supply first, call 999, and always ensure the casualty is seen by a doctor — even if they appear unharmed.

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13 min readUpdated 2026-05-18Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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Key Takeaways

  • 1NEVER touch a person who is still in contact with the electrical source — you risk becoming a second casualty. Isolate the supply first.
  • 2Call 999 immediately for any electric shock — even if the person appears unharmed, internal injury, cardiac damage, and delayed arrhythmia can occur.
  • 3If the casualty is unresponsive and not breathing normally, begin CPR immediately after calling 999. Early CPR is critical.
  • 4Low-voltage shocks (UK domestic 230V) can be fatal — voltage level alone is not a reliable guide to severity of injury.
  • 5Electric shock can cause delayed cardiac arrhythmia hours after the incident — anyone who has received a shock MUST be assessed by a doctor, even if they feel fine immediately afterwards.
  • 6High-voltage shocks (above 1,000V) cause additional injuries including severe internal burns along the current path — NEVER approach high-voltage equipment after an incident until the supply is confirmed isolated.
01 · First Aid Guide

CRITICAL: Do NOT Touch the Casualty While They Are in Contact with the Source

Do NOT touch the casualty if they are still in contact with the electrical source.

If you touch a person who is still connected to a live electrical source, current will pass through you as well. You will become a second casualty, incapacitated and potentially killed, leaving the original casualty with no help. This is how multiple fatalities from a single electrical accident occur.

The golden rule of electric shock first aid is:

  1. Make the situation safe first — isolate the supply
  2. Only then approach and help the casualty
  3. Call 999 — do this as soon as possible, ideally at the same time as step 1

This sequence is not about prioritising the power over the person — it is the only approach that allows you to actually help the casualty without becoming a casualty yourself.

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02 · First Aid Guide

How to Isolate the Electrical Supply

Isolating the supply removes the danger to both the casualty and to you. The method depends on the situation.

  • Turn off at the consumer unit — if the consumer unit is nearby and you can reach it safely without crossing the affected area, turn off the main switch. This isolates all circuits in the property.
  • Switch off the appliance at the wall — if the casualty is in contact with an appliance (a faulty tool, appliance, or lead), switch off or unplug it at the wall socket — not the appliance switch, as the fault may be in the appliance itself.
  • If you cannot switch off the supply — use a dry, non-conducting object to move the source away from the casualty or the casualty away from the source. Suitable materials include a dry wooden broom handle, a folded dry newspaper, or a dry rubber mat. Do not use anything damp, metal, or wet. Stand on a dry, insulating surface if possible.
  • High voltage — do not approach — if the source is high voltage (overhead power lines, railway electrification, substations), do not approach within 15 metres. Call 999 immediately and keep bystanders well back. Only approach when the relevant authority confirms the supply is isolated.
03 · First Aid Guide

Call 999 — Always, for Every Electric Shock

Call 999 immediately for any electric shock, regardless of how the casualty appears. Do not delay calling because the person says they feel fine. Electric shock injuries include delayed effects that make immediate medical assessment essential for every case.

  • Tell the emergency operator:
    • That the casualty has received an electric shock
    • Whether they are conscious and breathing
    • The exact location
    • Whether the supply has been isolated
    • Any visible injuries
  • Do not hang up — the emergency operator will guide you through what to do while the ambulance is on its way. Follow their instructions exactly.
  • If a bystander is present — direct a specific person to call 999 while you begin first aid. Say: "You — call 999 now and tell them someone has had an electric shock at [address]." Giving a specific person the task ensures it is done.
04 · First Aid Guide

CPR If the Casualty Is Not Breathing

Once the casualty is away from the electrical source and you are certain you are not at risk of electrocution, check for response and breathing. If the casualty is unresponsive and not breathing normally, begin CPR immediately. Early CPR is the single most important factor in survival from cardiac arrest.

  1. Check for response — call their name and tap their shoulders firmly. If no response, shout for help.
  2. Open the airway — tilt the head back gently by placing one hand on the forehead and lifting the chin with two fingers. Look for no more than 10 seconds for normal breathing (normal breathing is not occasional gasps).
  3. Start chest compressions — place the heel of one hand on the centre of the chest (lower half of the breastbone). Place your other hand on top and interlace your fingers. Press down 5 to 6 cm, keeping your arms straight. Compress at a rate of 100 to 120 per minute (the beat of "Stayin' Alive" by the Bee Gees is a useful guide).
  4. Rescue breaths (if trained) — after every 30 compressions, give 2 rescue breaths: pinch the nose, seal your lips over the casualty's mouth, and blow steadily for about 1 second. If you are not trained or not confident in rescue breaths, continue with compressions only — hands-only CPR is effective.
  5. Use an AED if available — Automated External Defibrillators (AEDs) are available in many public places. Send a bystander to find one while you continue CPR. Follow the AED's voice instructions exactly — they are designed to be used by untrained bystanders.
  6. Continue until help arrives — do not stop CPR until a paramedic takes over, the casualty shows signs of life (normal breathing, movement), or you are physically unable to continue.
05 · First Aid Guide

Low Voltage vs High Voltage: How Severity Differs

The terms "low voltage" and "high voltage" have specific technical meanings, but the key point is: both can be fatal. Low voltage does not mean low risk.

  • Low voltage (up to 1,000V AC) — includes UK mains (230V)

    UK domestic mains electricity (230V, 50Hz AC) is fully capable of causing cardiac arrest. The 50Hz frequency of UK mains is particularly dangerous because it falls within the range most likely to induce ventricular fibrillation. The path of current through the body is critical — hand-to-hand or hand-to-foot paths passing through the chest carry the highest risk of cardiac injury. Burns at the contact points may be visible but are not a reliable guide to internal injury severity.

  • High voltage (above 1,000V AC) — power lines, railway, substations

    High-voltage shocks cause additional injury patterns not seen with domestic voltages. The current travels through the body along the path of least resistance (nerve sheaths, blood vessels), causing deep internal burns from entry to exit point. Flash burns from the electrical arc can cause severe surface burns even without direct contact. Tetanic muscle contraction may cause fractures or joint dislocations from the violent involuntary movement. Blast injuries from the arc explosion can occur. High-voltage injury is a major trauma requiring specialist burns and surgical care.

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06 · First Aid Guide

After Treatment: Why Everyone Must See a Doctor

Anyone who has received an electric shock — even if they appear completely unharmed — must be assessed by a doctor. This is not optional.

  • Internal burns are not visible — current passing through the body can cause internal burns along blood vessels and nerves that cause no immediate pain or visible surface injury.
  • Cardiac monitoring is required — the heart's conduction system may have been disrupted without causing immediate arrest. An ECG (electrocardiogram) is needed to assess the heart rhythm. Abnormalities may not be immediately apparent and may require monitoring over several hours.
  • Secondary injury from falls — electric shocks can cause violent involuntary muscle contraction and unconsciousness, leading to falls and impact injuries. Head injury from a fall must be assessed and ruled out.
  • Tetanic muscle contraction injuries — severe involuntary muscle contraction can be strong enough to cause fractures of the long bones or dislocations of major joints. These may not be immediately obvious in the post-shock confusion.

Do not allow a shock casualty to drive themselves to hospital or to be left alone in the hours after an incident. They must be accompanied to Accident and Emergency or taken by ambulance.

07 · First Aid Guide

Delayed Cardiac Arrhythmia: The Hidden Risk

One of the most serious and least-understood aspects of electric shock injury is the risk of delayed cardiac arrhythmia — abnormal heart rhythms that develop in the hours after the incident rather than immediately.

  • What happens — the electrical current can cause temporary disruption to the heart's conduction system (the electrical signals that coordinate the heartbeat). The heart may continue to beat normally immediately after the shock, but the myocardium (heart muscle) may have been damaged or irritated sufficiently to trigger ventricular fibrillation or other dangerous arrhythmias hours later.
  • Documented time frame — delayed arrhythmias have been documented occurring up to 24 hours after the initial shock. The risk is highest in the first 12 hours. This is why medical protocols call for ECG monitoring for at least 12 to 24 hours for any significant shock exposure.
  • Warning symptoms — anyone who has received an electric shock should seek immediate emergency attention if they develop any of the following in the hours after the incident: chest pain or tightness, palpitations (awareness of irregular or rapid heartbeat), dizziness or fainting, difficulty breathing, or confusion.

This is why even a person who received a seemingly minor shock and feels fine immediately must be seen by a doctor. A brief ECG in A&E and a period of monitoring can be life-saving.

08 · First Aid Guide

Prevention: Reducing the Risk of Electric Shock

The best electric shock first aid is never needing it. Most domestic electric shock incidents are preventable.

  • Test your RCD monthly — a functioning 30mA RCD can trip fast enough to prevent a fatal shock in many situations. Test by pressing the test button on your consumer unit monthly. See our home electrical safety guide for full testing instructions.
  • Use RCD-protected extension leads for power tools — when using power tools, always use an RCD-protected extension lead or a plug-in RCD adaptor rated at 30mA. See our guide on extension lead safety.
  • Replace damaged cables immediately — never use appliances with damaged leads. Replace flexes rather than wrapping them with tape.
  • Have your installation inspected regularly — an Electrical Installation Condition Report (EICR) every ten years for owner-occupied homes identifies hidden wiring faults before they cause accidents.
  • Learn CPR — consider taking a first aid course that includes CPR. The British Red Cross and St John Ambulance offer courses throughout the UK. Knowing how to perform CPR could save a life.

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