Fishy or Burning Smell in the House: Is It Electrical?
If your house smells of fish and nobody has cooked any, treat it as an electrical warning until you have ruled it out. Electricians know the smell well: some of the heat resistant plastics used in plugs, sockets, switches and fittings give off a sharp fishy or urine like odour as they overheat, often before they visibly burn. Find the source, switch it off, and do not use it again until it has been checked.
A plain burning smell carries the same warning. The steps are the same for both.
If you smell it right now
Work through this calmly, in order:
Smoke or flames? Get everyone out, close the doors behind you and call 999. Do not go back in to switch anything off.
Follow your nose room by room. The smell is usually strongest close to the source.
Check for heat without grabbing. Hold the back of your hand close to sockets, plugs, adaptors, light switches and dimmer switches. A warm phone charger is normal; a plug or socket faceplate giving off real heat is not.
Switch off and unplug the suspect item if it is safe to reach and not visibly scorched or melting. If the plug or socket is hot, scorched or discoloured, do not pull the plug: switch that circuit off at the consumer unit instead, then unplug once it has cooled.
If you cannot find it, or the smell is coming from the consumer unit itself, switch off the main switch if you can reach it without touching anything hot or smoking, and call an emergency electrician to trace it.
Never take the cover off a socket, switch or the consumer unit to look for the source, and do not keep testing a socket to see if the smell comes back.
Why overheating electrics smell of fish
Heat breaks down the chemicals in some of the heat resistant plastics used in electrical accessories and appliance housings, and that is what you smell. The fishy note often comes before any visible damage, which makes it a useful early warning. By the time the plastic turns brown or the smell becomes an obvious burnt plastic smell, the fitting has been running hot for a while.
Electrical Safety First says half of accidental domestic fires in the UK are caused by electricity, and lists burn marks, buzzing or crackling, fuses blowing, breakers tripping and anything hot to the touch as signs to act on.
Where the smell usually comes from
In our experience the source is usually one of these:
A plug with a loose terminal or wrong fuse. A loose screw on a terminal creates resistance and heat right inside the plug top. Electrical Safety First advises replacing a fuse only with one of the same rating, and says a standard UK plug usually takes a 3 A or 13 A fuse.
A worn socket. Old sockets lose grip on the plug pins over time. Poor contact makes heat, and you may see brown marks around one pin hole.
An overloaded adaptor or extension lead. Most extension leads are rated at 13 A (about 3,000 W in total), and some older leads and cable reels are rated lower. A heater plus a kettle on one lead goes over that.
A dimmer switch. Dimmers run warm by design, but one that is hot, buzzing or smelly is overloaded or failing, often after bulbs were swapped for a type it was not rated for.
A light fitting. Lamps above their rated wattage cook the lampholder and the wiring above it. Electrical Safety First lists curled labels, discolouration and scorch marks on light fittings as warning signs.
The consumer unit. A loose connection on a busbar or main cable can heat up inside the enclosure. If the smell is at the board, do not open it. Call an electrician.
An appliance. Motors and elements in washing machines, tumble dryers, fan heaters and extractor fans can overheat internally.
Hot plug or hot socket: what it means
A plug getting hot is one of the most common versions of this problem. The usual causes are a loose connection in the plug, a worn socket, or a high load such as a heater, tumble dryer or kettle running for a long time.
Do not keep swapping a hot plug between sockets to find out which is to blame. With the circuit off and everything cooled, look instead: brown marks on the plug pins or a softened plug top point to the plug or its flex, while discolouration around the pin holes points to the socket. Stop using both until they are checked. A like for like socket replacement is not notifiable, but a socket that has overheated may have damaged the cable behind it too, so it needs checking by an electrician. If the socket has also stopped working, our guide to a plug socket not working covers the checks.
When it is an emergency
Some smells can wait for a booked visit once the item is unplugged. These cannot, and need an electrician the same day:
the smell is coming from the consumer unit, a wall socket or a light fitting rather than an unplugged appliance;
the smell continues after you have unplugged everything nearby;
you can see scorching, melting or smoke stains on a faceplate;
you hear buzzing or crackling from a socket, switch or the board;
breakers or the RCD have also been tripping. Our post on whether it is dangerous if a circuit breaker keeps tripping explains why the two together matter.
Flames or smoke are always a 999 call first.
Smells that are not electrical
Not every fishy or burning smell is your wiring. Rule these out once the electrics are safe:
Dust burning off a heater the first time it is used after summer. It smells for a few minutes, then stops.
Drains and traps that have dried out in an unused bathroom, or a blocked sink trap.
Something that has died under the floor or in a wall cavity, which usually gets worse over days.
New furniture, carpets or paint, which can give off chemical smells for a while.
Gas, which smells of rotten eggs rather than fish. If you smell gas, do not operate any switches, open doors and windows, leave, and call the gas emergency number, 0800 111 999.
Burning smell questions, answered
Can a light switch smell of fish?
Yes, particularly dimmer switches and old switches with loose terminals. Switch the light off at the switch, leave it off, and have the switch checked.
Why does my house smell fishy only when the heating is on?
That points to an electric heater, an immersion heater, a boiler's electrical controls or a fused spur feeding them, all of which carry load when the heating runs. Check those plugs and spur faceplates for heat or discolouration first, without opening anything.
Should I get my wiring inspected after a fishy smell?
If the cause was an overheated socket, switch or connection, yes. One loose terminal is often a sign of others, and an EICR inspects and tests the whole installation to find them.
If you have a fishy or burning smell in the house in Shifnal, Telford, Wolverhampton or across the West Midlands, switch the suspect item off and call our team so we can find the source before it gets worse.
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