The honest answer is no. Not in the way most people use them. Extension leads are designed for temporary use, and the fact that they survive years of permanent use in most homes doesn’t mean they’re safe. It means the consequences haven’t happened yet.
This guide explains why permanent extension lead use is a genuine hazard, what the specific risks are for different types of lead, and what the right solution is.
What Extension Leads Are Designed For
An extension lead is designed to provide a temporary supply to an appliance that cannot conveniently reach a fixed socket outlet. The word temporary is doing a lot of work there. In practice, the extension lead behind most people’s televisions has been in that position for years. The one under the desk has been there since the desk was moved in. The one in the kitchen has been powering the microwave and the coffee machine since the last tenant moved out.
BS 7671, the IET Wiring Regulations 18th Edition, is clear at Regulation 553.1.7 that socket outlets should be provided in sufficient numbers to avoid the need for extension leads and adaptors in normal use. The regulation exists precisely because extension leads, used permanently and casually, represent a significant and largely invisible risk.
Electrical Safety First reports that electrical faults account for 53.4% of all accidental dwelling fires in England, and overloaded extension leads and sockets are a recognised contributor to that figure. This is not a theoretical risk.
Not All Extension Leads Are Equal: Ratings and Cable Quality
One of the most important things to understand about extension leads is that they are not all rated the same, and the rating matters enormously when high-draw appliances are connected.
Extension leads commonly sold in the UK are rated at 5A, 10A, or 13A. The rating refers to the maximum current that can be safely drawn through the lead continuously without the cable overheating.
A 5A lead, often found as a single-socket trailing lead with a lightweight cable, is suitable only for low-power equipment such as lamps, phone chargers, and small electronics. The plug on a 5A lead should be fused at 5A. If someone fits or leaves a 13A fuse in a lead that is only rated for 5A, the fuse will not blow until the current reaches 13A, by which time the cable itself will have been carrying more than double its rated load for some time and may already be seriously overheating.
A 10A lead is suitable for moderately loaded applications but not for high-draw appliances. A 13A lead, using appropriately sized cable throughout, can safely carry up to 3,000 watts of continuous load, though in a multi-outlet strip this is the total across all outlets combined, not 13A per socket.
The cable gauge inside the lead is the physical determinant of its current-carrying capacity. Thinner cable has higher resistance and generates more heat for a given current. A long lead with undersized cable is more dangerous than a short lead of the same rating because the resistance increases with length. Cheap, unbranded extension leads frequently use undersized conductors even when the packaging implies a 13A rating. A lead with thin, flexible cable that noticeably warms up under moderate load is a lead with inadequate conductors for its claimed rating. The correct test is whether the lead is certificated to the relevant British Standard, not whether it has a 13A fuse in the plug.
A fused strip lead offers better protection than an unfused one, because the fuse in the plug protects the lead cable itself. However, the fuse only protects against a fault large enough to blow it. It does not protect against the sustained overloading that causes gradual heating, insulation breakdown, and eventual fire.
The Overloading Problem
Every appliance draws a current that can be expressed in amps. High-draw appliances include electric kettles (around 10 to 13A), toasters (around 8 to 10A), electric irons (around 10 to 13A), hair dryers and straighteners (around 8 to 13A), fan heaters (around 8 to 13A), and tumble dryers (around 10 to 13A). These are the appliances that can individually approach or reach the maximum rating of a 13A lead on their own.
The problem occurs when multiple appliances share a multi-gang extension lead. A television, a games console, a soundbar, and a phone charger are a perfectly reasonable combination that sits well within 13A total. A kettle, a toaster, and a microwave sharing a four-gang strip behind the kitchen worktop can easily exceed it. The fuse in the plug will protect against a serious overload but will not trip at the point where sustained heating begins. The lead will run warm. Over time the insulation degrades. The connections at the socket outlets begin to work loose. A fault develops that may not announce itself clearly until it is well advanced.
The daisy-chain is the most dangerous configuration of all. Plugging one extension lead into another does not double the capacity. The first lead in the chain must carry the combined load of everything connected to the second, and possibly a third. The fuse in the original plug protects against a catastrophic overload but not against the sustained heating that develops from running near capacity. The London Fire Brigade is explicit that daisy-chaining is one of the most common causes of preventable electrical fires in UK homes.
Extension Reels and the Coiled Cable Hazard
Extension reels, the drum-type leads on a winding mechanism, introduce an additional and very specific hazard that is not well understood by most people who use them.
A cable carrying electrical current generates heat as a natural consequence of the resistance in the conductors. Under normal circumstances this heat dissipates into the surrounding air and the cable remains at a safe temperature. When the same cable is coiled onto a reel, the heat from each turn is trapped by the turns next to it. The tightly packed coil cannot dissipate heat effectively, and the temperature of the cable rises with use. The more current drawn and the longer the reel is in use, the more the temperature rises.
Most extension reels carry two ratings printed on the drum or label: a higher rating for use when fully unwound, and a significantly lower rating for use while coiled. A reel might be rated at 13A fully unwound but only 5A or 6A while coiled. This is not a recommendation. It is a warning. Using a 13A appliance through a coiled reel rated at 5A coiled is asking the cable to carry more than twice its safe continuous load in a configuration where the heat cannot escape.
The consequences of ignoring this are documented. Cables have melted together in their coil, fusing the insulation of adjacent turns. In more serious cases, overheated drum reels have started fires. The County Durham and Darlington Fire and Rescue Service specifically warns that cable drum extension leads must be completely unwound before use to prevent overheating.
The correct approach is simple and non-negotiable: always fully unwind a cable reel before connecting any load to it, regardless of whether the full cable length is needed. If only two metres are required, unwind the full ten metres anyway and lay them out or loop them loosely. A coiled reel in use is not just a minor inconvenience. It is a fire waiting for conditions to be slightly worse than average.
Some extension reels include a thermal cut-out device, a small button that trips if the reel overheats, cutting the supply until it cools and is manually reset. This is a useful safety feature but not a substitute for correct use. A thermal cut-out that trips under load is telling you the reel is being used incorrectly, not that everything is fine now it has been reset.
The Physical Damage Risk
Extension leads run under carpets, through doorways, pinched behind heavy furniture, or bent repeatedly at the same point develop internal damage that is invisible from the outside. The cable sheath may appear intact while the conductors inside have fractured or the insulation between them has worn through.
A damaged cable can cause a short circuit or develop an intermittent arcing fault. Arcing faults generate intense localised heat that can ignite surrounding materials without the fault current being large enough to trip the protective device. This is one of the reasons Arc Fault Detection Devices are becoming more common in modern installations, but an extension lead under a carpet is not protected by the AFDD in the consumer unit in the same way a fixed installation would be.
Running a cable under a carpet is one of the most consistently cited causes of extension lead fires. The carpet compresses the cable, restricts heat dissipation, prevents visual inspection of damage, and provides combustible material immediately adjacent to any fault that does develop. It is not acceptable in any circumstances regardless of the load or the quality of the lead.
Outdoor Use: Most Extension Leads Are Not Suitable
The vast majority of domestic extension leads sold in UK shops carry an IP20 rating or no IP rating at all. IP20 means the lead is protected against solid objects larger than 12mm but has no water resistance whatsoever. It is rated for indoor use in dry conditions only.
Using a standard domestic extension lead outdoors, even temporarily, exposes it to moisture, dew, rain splash, and ground water. Water ingress into an unprotected extension lead or its socket outlets creates a direct path to earth that will trip the RCD on the circuit, but only if the circuit has RCD protection. A circuit without RCD protection, which is still found in older properties, offers no protection against the shock or fire risk created by a wet extension lead in contact with the ground.
For outdoor use where a fixed weatherproof socket is not available, only leads rated to at least IP44 (splash-resistant) should be used, and the connection between the lead and the socket outlet should be kept off the ground and away from water. For any sustained outdoor power requirement, a properly installed weatherproof socket outlet on a dedicated RCD-protected circuit is the correct answer.
Outdoor extension leads used for garden power tools, pressure washers, or EV charging are frequently left coiled, plugged in for extended periods, and used in wet conditions. Each of these factors alone increases risk. Combined, they represent a serious and avoidable hazard.
Where the Risk Is Highest
Kitchens: High-draw appliances, moisture, and the temptation to run multiple appliances from a single strip make the kitchen one of the highest-risk environments for extension lead misuse. Kettles, toasters, and microwaves should not share a single extension lead. Each should have its own fixed socket outlet.
Bedrooms: Chargers left connected overnight, multiple devices on a single lead, and the occupant being asleep when a fault develops make bedrooms the location where electrical fires most frequently cause injury. The fire that starts in a bedroom at 2am is not one that wakes the household in time.
Garages and workshops: Heavy power tools draw high starting currents, leads are frequently damaged by being driven over or crushed, and the environment is often damp. A domestic extension lead in a garage workshop is almost always the wrong tool for the job.
Outdoors: As covered above, virtually every domestic extension lead is unsuitable for outdoor use. Even a brief shower can render a standard lead dangerous.
The Right Solution
The only permanent solution to permanently needing power in a location is a fixed socket outlet. This is not a counsel of perfection. It is what BS 7671 requires, and it is what decades of fire statistics support.
Adding a socket to an existing ring main or radial circuit is typically straightforward where the existing wiring is in good condition. The cost of having a qualified electrician install one or two additional double sockets is modest. The cost of an electrical fire, in property, in insurance consequences, or in human terms, is not.
If adding fixed sockets is not immediately possible, the interim approach should be: use only leads that are correctly rated for the load, never daisy-chain, keep all cables fully visible and accessible, never run under carpets or behind furniture permanently, never use coiled reels under load, and use RCD-protected leads where available for higher-risk applications.
But the interim approach should be exactly that, interim. The extension lead that has been in the same position for three years has ceased to be a temporary solution and become a permanent risk.
Talk to Flodman Electrical
Flodman Electrical are NAPIT-approved electricians based in Farnborough, covering Hampshire, Surrey, and Berkshire. If your home has insufficient socket outlets and extension leads have become a permanent fixture, we can assess what is needed and install additional sockets cleanly and correctly. We also carry out EICRs to assess the overall condition of your electrical installation.
Contact Flodman Electrical to discuss adding sockets to your home
Flodman Electrical Ltd, NAPIT Approved Contractor. Serving Farnborough, Hampshire, Surrey and Berkshire.
