Extension leads are found in almost every home, providing a convenient way to power devices when wall sockets aren't in the right place. However, they're also one of the most common causes of electrical fires in UK homes. Misuse of extension leads causes thousands of fires each year, many of which could be prevented with basic safety knowledge. This guide covers everything you need to know to use extension leads safely.
The Hidden Danger of Overloading
The most common and dangerous mistake people make with extension leads is overloading them. Every extension lead has a maximum power rating – typically 13 amps or 3,120 watts for a standard UK extension. Exceeding this rating causes the cable to overheat, which can melt the insulation and start a fire.
The problem is that most people don't think about the total power draw of everything plugged into an extension. A four-gang extension doesn't mean you can safely plug in four high-power appliances – it means you can plug in devices that together don't exceed the extension's rating.
High-Power Appliances to Watch
Some common household appliances draw significant power:
- Electric heater: 2,000-3,000W
- Kettle: 2,200-3,000W
- Iron: 1,000-2,800W
- Hair dryer: 1,000-2,200W
- Toaster: 800-1,500W
- Microwave: 600-1,200W
- Vacuum cleaner: 500-2,000W
As you can see, just one kettle or heater can use almost the entire capacity of an extension lead. Plugging a heater and a kettle into the same extension would significantly exceed its rating.
The Coiled Cable Problem
Many people don't realise that a coiled extension cable is much more dangerous than an uncoiled one. When cable is wound on a reel, it can't dissipate heat effectively. The heat builds up in the coil, and the cable can reach dangerous temperatures even when not overloaded.
Cable reels typically have two ratings:
- Coiled rating: Usually around 5-6 amps (1,200W)
- Uncoiled rating: Usually 13 amps (3,120W)
This means a cable reel that's safe for a 3kW heater when fully unwound might only be safe for a 1kW device when coiled. Always fully unwind cable reels before use, even if you don't need the full length.
Daisy-Chaining: A Dangerous Practice
"Daisy-chaining" means plugging one extension lead into another to extend the reach or add more sockets. This is extremely dangerous and should never be done. Here's why:
- It increases the risk of overloading
- It creates more points of potential failure
- It can overload the wall socket
- It increases voltage drop, which can damage equipment
- It's against electrical safety guidelines
If you need more sockets or longer reach, buy a single extension lead that meets your needs, or better yet, have additional sockets installed. Our socket installation service can add sockets wherever you need them.
Block Adapters: Another Risk
Block adapters (also called cube adapters or multi-plugs) that plug directly into a wall socket and provide multiple outlets are particularly risky. They put significant strain on the wall socket, and if overloaded, can cause the socket to overheat. The weight of multiple plugs can also cause the adapter to pull away from the socket, creating a poor connection that generates heat.
If you must use a multi-plug adapter:
- Never use more than one per socket
- Don't plug in high-power devices
- Check it doesn't feel warm during use
- Consider it a temporary solution only
Signs Your Extension Lead Is Unsafe
Replace your extension lead immediately if you notice:
- Warmth: The cable, plug, or sockets feel warm to the touch
- Burning smell: Any smell of burning plastic
- Discolouration: Yellowing or browning of the plastic
- Damage: Cuts, cracks, or exposed wires in the cable
- Loose sockets: Plugs don't fit snugly
- Sparking: Sparks when plugging in devices
- Intermittent power: Devices cutting in and out
Choosing Safe Extension Leads
When buying extension leads, look for:
- BS 1363 approval: Confirms it meets UK safety standards
- Appropriate length: Don't buy longer than you need
- Surge protection: Protects sensitive electronics
- Individual switches: Allows you to turn off unused sockets
- Adequate rating: Check it's suitable for your intended use
- Quality brand: Avoid very cheap, unbranded products
Extension Lead Safety Rules
Follow these rules to use extension leads safely:
- Calculate the load: Add up the wattage of all devices and ensure it doesn't exceed the extension's rating
- Uncoil fully: Always fully unwind cable reels
- No daisy-chaining: Never plug one extension into another
- Keep dry: Never use extension leads in wet conditions unless specifically rated for outdoor use
- Don't cover: Never cover extension leads with rugs, furniture, or other items that trap heat
- Check regularly: Inspect for damage and replace if necessary
- Turn off when not in use: Reduces fire risk and saves energy
- Don't run under carpets: This traps heat and hides damage
- Avoid trip hazards: Position cables safely
- Use temporary only: Extension leads shouldn't be permanent solutions
When to Call an Electrician
If you find yourself relying heavily on extension leads, it's a sign that your home doesn't have enough sockets for your needs. This is common in older properties that were designed before we had so many electrical devices.
Rather than continuing to use extension leads as a permanent solution, consider having additional sockets installed. This is:
- Safer than using extension leads
- More convenient
- Better for your home's value
- More aesthetically pleasing
Our domestic electrician services include socket installation throughout your home.
Extension Leads and Specific Appliances
Heaters
Portable heaters should ideally be plugged directly into wall sockets, not extension leads. If you must use an extension, ensure it's fully uncoiled, rated for the heater's wattage, and nothing else is plugged into it.
Kitchen Appliances
High-power kitchen appliances like kettles, toasters, and microwaves should be plugged directly into wall sockets. The kitchen is one area where having enough sockets is particularly important.
Computing Equipment
Computers and peripherals are generally low-power and safe for extension leads. Consider a surge-protected extension to protect sensitive electronics from power spikes.
Phone Chargers
Phone and tablet chargers are very low power (typically 5-20W) and are safe to use with extension leads. However, avoid leaving chargers plugged in when not in use.
Outdoor Extension Leads
Using extension leads outdoors requires extra caution:
- Use only extension leads rated for outdoor use (IP44 or higher)
- Ensure the wall socket is RCD protected
- Keep connections off the ground and protected from rain
- Never use indoor extension leads outside
- Unplug when not in use
For regular outdoor power needs, consider having a weatherproof outdoor socket installed. Our outdoor power installation service can provide safe, permanent outdoor power.
Conclusion
Extension leads are useful tools, but they must be used correctly to be safe. Overloading, daisy-chaining, and using damaged leads are the main causes of extension lead fires. By following the safety guidelines in this article, you can significantly reduce the risk of electrical fires in your home.
If you're using extension leads as a permanent solution because you don't have enough sockets, consider having additional sockets installed. It's a relatively inexpensive improvement that makes your home safer and more convenient.
Need More Sockets?
Stop relying on extension leads – get permanent sockets installed.