Two things make electricity different from other injuries: the danger is still present when you arrive, and the visible wound is almost never the injury.
1. Making it safe
| Situation | What to do |
|---|---|
| Domestic supply, indoors | Isolate at the consumer unit, or unplug at the socket. If neither is possible, move the source away with something dry and non-conducting — a wooden broom handle, a plastic chair — standing on something dry. This is a last resort, not a technique |
| Overhead power lines | Stay at least 25 metres away and keep everyone else back. Electricity arcs and travels through the ground — you do not have to touch anything. Only the network operator can confirm the line is dead, and a line that has fallen may reenergise automatically. Call 999 and say overhead line |
| Railway lines | Third rail and overhead catenary both remain live until an operator isolates them. Do not go on the track |
| A vehicle in contact with a cable | Tell the occupants to stay inside. The car is a safer place than the ground beside it. If they must get out because of fire, they should jump clear without touching the vehicle and ground at once, then shuffle away with both feet together and never step |
| Water involved | Water spreads the hazard. Isolate before entering any wet area |
2. Then treat them
Unresponsive and not breathing normally: CPR and a defibrillator, immediately
Electrical injury is one of the situations most likely to produce a shockable rhythm in an otherwise healthy heart, and outcomes from prompt resuscitation are correspondingly good — better than for most causes of arrest. It can also stop breathing while the heart continues, by paralysing the chest muscles or the respiratory centre, so rescue breaths matter here more than in a typical adult arrest. Follow the resuscitation chapter and keep going.
Assume a fall as well as a shock
Being thrown, or falling from a ladder or roof, is part of most serious electrical injuries. Treat the neck and spine as potentially injured, and look for the fractures nobody mentioned.
Look for two burns, not one
An entry wound and an exit wound — commonly a hand and a foot. Small, deep, and often painless. Cool them and cover as in burns and scalds.
Everyone with more than a trivial shock gets assessed
Criteria in section 4. The point is that looking well does not settle it.
Why the skin tells you almost nothing
- Current takes the shortest path between entry and exit and heats everything on the way. Muscle, nerve and blood vessel conduct better than skin, so the damage runs deep along the track while the surface shows two small marks.
- Deep muscle injury releases myoglobin, which damages the kidneys — the same mechanism as crush injury. This is why a person with two unimpressive burns can need intravenous fluids and blood tests.
- Limb swelling inside its fascial compartments can cut off circulation hours later, and needs surgery to release. Increasing pain, tightness, numbness or a cold hand or foot after an electrical injury is an emergency.
- Alternating current locks muscles on — the reason a hand grips a live wire rather than dropping it, and the reason contact times with domestic AC are longer than people assume.
- The heart's electrical system can be upset without any burn at all. A current across the chest is what matters, not the size of the mark.
3. Lightning, which behaves differently
- Someone struck by lightning is safe to touch. They hold no charge. Nobody should hesitate.
- Reverse the usual triage. In a group struck together, treat the ones who appear dead first — the opposite of every other multiple-casualty situation. Lightning typically causes a brief arrest from which people recover well with immediate CPR, while those who are moving and groaning are, for the moment, alive. This is the single most important thing to know about it.
- Expect temporary paralysis, deafness and confusion that resolve. Limbs may be blue, mottled and pulseless for a period and then recover.
- Look for ruptured eardrums, and for eye injury including cataract developing later.
- Lightning strikes indoors are not impossible — through plumbing, wiring and corded phones. The safest place in a storm is a substantial building or a hard-topped vehicle, away from windows, plumbing and wired electronics. Not a shelter, not a tree, not high ground.
- The 30-30 rule: if thunder follows the flash within 30 seconds, the storm is close enough to strike you; wait 30 minutes after the last thunder before going back out.
4. Who needs a hospital, and who needs monitoring
| Assessment needed — and cardiac monitoring — if | Usually fine after a look |
|---|---|
| Any loss of consciousness, however brief High voltage, lightning, or any industrial supply Current likely to have crossed the chest — hand to hand, or hand to opposite foot Any palpitations, chest pain or breathlessness Burns, particularly two of them A fall, or any injury from being thrown Wet skin at the time, which lowers resistance and increases the current Known heart disease, a pacemaker, or pregnancy A child who has bitten or mouthed a cable — and this one carries an action beyond the assessment. An oral commissure burn can bleed heavily and suddenly from the labial artery around 5 to 14 days later, as the dead tissue separates. So it needs specialist review arranged before discharge, and the family must be told explicitly what to expect and what to do: pinch the lip firmly between finger and thumb, sit the child up, and call 999. A parent who has not been warned will not know that squeezing the lip is the correct first move |
A brief low-voltage domestic shock in a well adult with no symptoms, no burn, no loss of consciousness, dry skin, and a current path not crossing the chest — a finger touched on a socket, for example. Even then, advise them to seek help for any palpitations, dizziness or new pain |
On delayed arrhythmia, since it is widely believed and mostly wrong — and read this against the left-hand column above, not on its own: a person with none of the features in that list, with a normal heart trace and no symptoms after a low-voltage domestic shock, does not need prolonged monitoring — the risk of an arrhythmia appearing later out of nowhere is very low. What earns monitoring is the list on the left, not the shock itself. Getting this right matters in both directions: unnecessary admissions for trivial shocks, and discharged patients who should have been watched, are both common.