What is the first thing to do if someone receives an electric shock?

Do not touch the casualty until you are certain the electrical supply has been isolated. If you touch someone who is still in contact with a live electrical source, the current will pass through you and you will become a second casualty. Switch off the power at the consumer unit, isolator, or plug socket. If you cannot reach the power supply, use a dry non-conductive object (a wooden broom handle, a folded dry blanket, a rubber mat) to push the casualty away from the source — never use anything metal or wet. Only when you are certain the source is isolated should you approach the casualty.

How do I isolate the supply in an emergency?

In a domestic property, switch off the main switch at the consumer unit (the large switch at the top of the fuseboard). If you cannot reach the consumer unit, remove the plug from the socket if it is accessible. For electrical equipment plugged in, pull out the plug. Do not pull cables — they may be damaged. On a construction site, operate the site isolation switch or the nearest isolator. For high-voltage systems (overhead lines, substations), do not attempt to isolate — contact the network operator (National Grid, local DNO) or emergency services. Stand well back and keep others away.

Should I start CPR on someone who has had an electric shock?

Yes, if the casualty is unresponsive and not breathing normally, begin CPR immediately after confirming the electrical supply is isolated. Do not delay CPR to wait for an ambulance. Electric shock commonly causes ventricular fibrillation (VF) — a chaotic heart rhythm that prevents the heart from pumping blood. Without CPR, the brain begins to suffer irreversible damage within 4 to 6 minutes. CPR keeps blood circulating until an AED can deliver a shock to restore normal heart rhythm. Send someone else to call 999 and find an AED while you begin CPR. Thirty chest compressions followed by two rescue breaths — continue until the AED arrives or the casualty starts breathing normally.

Can 230V household electricity kill you?

Yes. The widely cited minimum lethal current through the heart is approximately 100mA — a tenth of an ampere. UK domestic circuits are protected by 32A breakers on ring main circuits and 6A or 16A on lighting and dedicated circuits. Even at skin contact resistance of 1,000 ohms (which is typical for dry skin contact), 230V produces 230mA — more than enough to cause ventricular fibrillation. Wet or broken skin dramatically reduces resistance, increasing current further. The duration of shock also matters — brief contacts may cause burns and muscle contraction without cardiac effects; prolonged contacts are more likely to cause VF. Never assume low voltage is safe.

What are entry and exit wounds from electric shock?

When current passes through the body, it enters at one point and exits at another. The entry wound is typically where the current first contacts the skin — often the hand or fingers. It may appear as a charred, grey, or depressed area. The exit wound is where the current leaves the body, often through the feet (to ground). Exit wounds are often more dramatic — the rapid vaporisation of tissue can cause an explosive appearance. Both wounds require hospital treatment. There is also internal damage along the path of the current — muscle necrosis, nerve damage, and cardiac injury may not be immediately visible.

How should I treat electrical burns at the scene?

Cool the burn with cool running water for 20 minutes. Do not use ice, ice-cold water, butter, toothpaste, or any other home remedy. Cover with a clean non-fluffy dressing or cling film (not wrapped tightly). Do not remove clothing that is stuck to the burn. Do not burst blisters. All electrical burns require hospital assessment, even if they appear minor — the extent of internal damage is not visible from the surface wound. While treating burns, continue to monitor the casualty for signs of cardiac arrest and be prepared to begin CPR.

Is first aid training compulsory for electricians?

The Health and Safety (First-Aid) Regulations 1981 require employers to provide adequate and appropriate first aid equipment, facilities, and personnel for their employees. For electrical contractors, this typically means at least one first aider on site and an appropriate first aid kit. The Management of Health and Safety at Work Regulations 1999 require employers to carry out a risk assessment identifying first aid needs. While specific first aid training is not mandated by name in the Electricity at Work Regulations 1989, the Construction (Design and Management) Regulations 2015 and many client site rules require first aid trained personnel on all construction sites. All practising electricians should hold at minimum a valid Emergency First Aid at Work (EFAW) certificate.

SAFETY CRITICAL

Electrical Rescue Procedure UK: Electric Shock First Aid

Life-saving guidance for responding to electrical accidents — safe isolation before touching the casualty, calling 999, CPR and AED use after electric shock, burn treatment, entry and exit wounds, and why all electricians need first aid training.

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12 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 someone who appears to be in contact with a live electrical source. You will become a second casualty. Isolate the power supply first — or use a non-conductive object to separate the casualty from the source if isolation is not immediately possible.
2After isolating the supply, call 999 immediately. Electric shock can cause cardiac arrest with no external symptoms — always treat as a medical emergency even if the casualty appears conscious.
3CPR should be started immediately if the casualty is unresponsive and not breathing normally. Electric shock causes ventricular fibrillation (VF) — the heart is in chaotic rhythm rather than stopped. An AED (automated external defibrillator) is the definitive treatment for VF. Commence CPR and send someone to find an AED.
4Electric current enters and exits the body, causing damage along its path. Look for both an entry wound (where current entered, often charred or depressed) and an exit wound (where current left the body, often explosive in appearance). Both require medical treatment.
5Household 230V AC can kill. The threshold for ventricular fibrillation is approximately 100mA through the heart — far below what a standard domestic circuit can deliver. Never underestimate low-voltage shock.

01 · Safety Critical

CRITICAL: Do NOT Touch the Casualty Until the Supply Is Isolated

If someone appears to be in contact with a live electrical source, touching them will pass current through you. You will become a second casualty.

This is the most important rule in electrical rescue. The instinct to help someone in distress is powerful — but reaching out to grab a casualty who is still connected to a live electrical source is one of the most common ways rescuers are killed. Control that instinct. Isolate first.

Signs that a casualty may still be in contact with a live electrical source include: visible sparking, the casualty gripping or frozen to a conductor (muscle tetanus caused by AC current at power frequency can lock the hand around a live conductor), smoke or burning from the point of contact, or the casualty being unable to release their grip.

If the casualty is clearly no longer in contact with the source and the source has been confirmed isolated, approach and begin assessment. But if there is any doubt — isolate first.

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02 · Safety Critical

How to Isolate the Supply Safely

Isolating the electrical supply is the first action in any electrical rescue. How you do this depends on the type of electrical system and the environment.

1Domestic property — switch off the main switch at the consumer unit (the large isolating switch at the top of the fuseboard). If a specific circuit is involved and you know which breaker controls it, switch that off as well. Pull out the plug if the item is plug-connected and the plug is accessible without touching the casualty.
2Construction site or commercial premises — use the site emergency stop or main isolator. These are typically clearly labelled and brightly coloured. On construction sites, the main isolator is usually located at the site distribution board or the temporary supply intake.
3Cannot reach the isolation point — if the isolation point is inaccessible, use a dry non-conductive object to push the casualty away from the source. A wooden broom handle, a dry rope, a folded dry blanket, or a rubber mat can be used. NEVER use anything metal, wet, or damp. Push the casualty away — do not pull them towards you.
4High voltage systems — do NOT attempt to isolate high-voltage overhead lines or substation equipment. Stand well back (at least 15 metres from any fallen overhead line), keep others away, call 999, and wait for the network operator. Only authorised engineers with specialist equipment can safely isolate HV systems.

03 · Safety Critical

Calling 999 — Always Treat as a Medical Emergency

Call 999 immediately after isolating the supply — even if the casualty appears conscious and uninjured. Electric shock causes internal injuries that are not immediately visible, including cardiac arrhythmias that can develop minutes or hours after the shock.

What to tell the 999 operator — state that this is an electrical injury, give the exact location, state how many casualties there are, describe the casualty's current condition (conscious/unconscious, breathing/not breathing), and confirm that the electrical supply has been isolated.
Do not leave the casualty — once on the phone, follow the operator's instructions. If another person is present, send them to guide the ambulance and locate an AED. Stay with the casualty and monitor their condition.
All electric shock casualties must go to hospital — even if the casualty refuses or says they feel fine. Cardiac arrhythmias, rhabdomyolysis (muscle breakdown), and internal burns can present with delayed symptoms. Paramedics will carry out an ECG on scene and transport for further monitoring.

04 · Safety Critical

CPR for Cardiac Arrest After Electric Shock

Electric shock commonly causes ventricular fibrillation (VF) — the heart goes into a rapid, chaotic rhythm that does not pump blood. VF is the leading cause of death from electric shock. CPR and an AED are the definitive treatments.

Check for response — shake the casualty's shoulders and call loudly "Are you all right?" If no response, shout for help and call 999 (or direct someone to call). Open the airway by tilting the head back and lifting the chin.
Check for normal breathing — look, listen, and feel for no more than 10 seconds. Occasional gasps (agonal breathing) do not count as normal breathing. If in any doubt — begin CPR.
30 chest compressions — place the heel of your hand on the centre of the chest. Place your other hand on top and interlace your fingers. Push down hard and fast — at least 5cm deep, at a rate of 100 to 120 per minute. Allow the chest to fully recoil between compressions.
2 rescue breaths — tilt the head back, lift the chin, pinch the nose, seal your mouth over theirs, and breathe steadily for about one second until the chest rises. Two breaths, then return to 30 compressions. If you are untrained or unwilling to give rescue breaths, hands-only CPR (compressions only) is better than no CPR.
AED as soon as possible — an automated external defibrillator delivers a controlled electric shock that can restore normal heart rhythm from VF. Many public buildings carry AEDs. Send someone to find the nearest one while CPR continues. The AED will guide you with voice instructions — follow them exactly.

Continue CPR without stopping until paramedics take over, the casualty starts breathing normally, or you are physically unable to continue.

05 · Safety Critical

Burn Treatment at the Scene

Electric shock causes burns at the points of entry and exit, and can cause internal thermal burns along the path of the current. Flash burns from electrical arcing can also cause severe surface burns to exposed skin.

Cool with running water for 20 minutes — use cool (not cold) running water. Start cooling as soon as possible — ideally within 3 minutes of the burn occurring. Cooling is effective for up to 3 hours after the burn.
Cover with cling film or a clean dressing — after cooling, cover loosely with non-fluffy cling film or a clean non-adhesive dressing. Do not wrap tightly — burns swell. Do not use ice, butter, toothpaste, or any home remedy.
Do not remove stuck clothing — if clothing is adhered to burned skin, do not attempt to remove it. Cut around the area if possible. Leave removal to medical professionals.
All electrical burns require hospital treatment — the surface wound does not reflect internal damage. Even a small entry wound may mask extensive internal muscle and nerve damage.

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06 · Safety Critical

Entry and Exit Wounds

Understanding the nature of electrical wounds helps you communicate effectively with the 999 operator and paramedics, and ensures that both injuries are treated.

Entry wound — typically located on the hand or fingers where the casualty made contact with the live conductor. Often appears as a charred, grey, or punched-out wound. May be relatively small, particularly from low-voltage DC sources. On AC systems, the entry point may show a dry, parchment-like appearance.
Exit wound — typically located on the foot, heel, or wherever the current completed its path to earth. Exit wounds are often more severe than entry wounds — the rapid vaporisation of body fluids causes an explosive appearance. Shoes and socks may be blown off.
Internal damage along the current path — muscles, nerves, and blood vessels along the path between entry and exit are damaged by the current. This damage (particularly muscle necrosis or rhabdomyolysis) may not be immediately apparent and can cause life-threatening kidney failure days later.

When giving information to paramedics, tell them both wound locations. This helps them understand the likely path of the current and the organs at risk.

07 · Safety Critical

Low Voltage vs High Voltage — When Can Each Kill?

A common and dangerous misconception is that low-voltage electricity (230V or 400V) is not as dangerous as high voltage. In practice, low-voltage electricity kills many people in the UK every year.

Low voltage (below 1,000V AC) — the threshold for ventricular fibrillation is approximately 100mA. UK domestic 230V circuits can deliver far more than 100mA through the body, even accounting for skin resistance. AC at 50Hz (UK mains frequency) is particularly dangerous because it causes muscle tetanus (sustained contraction), preventing the casualty from releasing their grip on a live conductor and prolonging the contact.
High voltage (above 1,000V AC) — high-voltage contacts cause immediate and severe burns, arc flash injuries, and blast injuries in addition to cardiac effects. The arc from a high-voltage flashover can extend across several metres — you do not need to touch HV equipment to be injured by it. HV contacts are more likely to cause cardiac arrest from the direct thermal effect on the heart rather than VF. Survival rates for HV contacts are lower than LV contacts.
Wet conditions — water dramatically reduces skin resistance and increases current for a given voltage. A 230V shock in dry conditions that causes a painful muscle contraction may cause cardiac arrest in wet conditions. Working around electrical equipment in the rain, in bathrooms, or in areas with standing water significantly increases the risk of electrocution.

08 · Safety Critical

First Aid Training — Why It Is Essential for Electricians

Electrical accidents happen quickly and without warning. Bystanders and colleagues at the scene have the best chance of saving a casualty's life — but only if they are trained. Every electrician should hold a valid first aid certificate.

Emergency First Aid at Work (EFAW) — one-day course covering CPR, AED use, management of unconscious casualties, burns, wounds, and shock. Valid for three years. This is the minimum recommended qualification for all electricians, particularly sole traders working alone.
First Aid at Work (FAW) — three-day course (or equivalent blended learning). Required for designated first aiders on larger sites. Covers a broader range of medical emergencies and is the standard required by many principal contractors on construction sites.
AED training — modern AEDs are designed to be used by untrained bystanders, but formal training in their use builds confidence. Many first aid courses include AED practical sessions. Know where the nearest AED is located on every site you work on.

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09 · Safety Critical

For Electricians: Emergency Procedure Documentation

Your RAMS (Risk Assessment and Method Statement) must include an electrical emergency procedure for every project. This documents what to do in the event of an electric shock, who the first aider is, where the nearest AED is located, and how the electrical supply can be isolated in an emergency.

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Frequently Asked Questions About Electrical Rescue

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Electrical Rescue Procedure UK: Electric Shock First Aid

Key Takeaways

CRITICAL: Do NOT Touch the Casualty Until the Supply Is Isolated

Get the BS 7671 A4:2026 Cheat Sheet — free

How to Isolate the Supply Safely

Calling 999 — Always Treat as a Medical Emergency

CPR for Cardiac Arrest After Electric Shock

Burn Treatment at the Scene

Generate RAMS in minutes

Entry and Exit Wounds

Low Voltage vs High Voltage — When Can Each Kill?

First Aid Training — Why It Is Essential for Electricians

Include rescue procedures in your site RAMS

For Electricians: Emergency Procedure Documentation

Generate Site RAMS with Emergency Procedures

Frequently Asked Questions About Electrical Rescue

What is the first thing to do if someone receives an electric shock?

How do I isolate the supply in an emergency?

Should I start CPR on someone who has had an electric shock?

Can 230V household electricity kill you?

What are entry and exit wounds from electric shock?

How should I treat electrical burns at the scene?

Is first aid training compulsory for electricians?

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