Even if you have perfectly thought out the location of each outlet at home, sooner or later a situation will happen in which you will need to use an extension cord. You will have to go to the store, where the flour of choice will begin. At first glance, everything is simple. It is necessary to take the one where the wire is longer, the number of outlets is larger, and the price is lower. This approach can be used if you are going to connect a table lamp or blender. If we are talking about a more powerful technique, then you will have to delve into the issue a little. So which extension cord should you choose for your home? we study the topic together.
First, a little theory – let’s deal with all the variety that you will surely find on store shelves. So, depending on the purpose and design features, extension cords are:
household – the simplest and most affordable. The socket strip can be equipped with a power button – this is the maximum functionality for this type of device. Grounding may or may not be. The length of the wire varies from 1.5 to 10 m, the cross-section is from 0.75 to 1.5 mm, which determines the maximum power of simultaneously connected devices, but we will talk about this later. Conventional extension cords can be connected to each other, but they have no short circuit protection;
surge protectors are advanced extension cords that are equipped with additional options. The contactor protects against overvoltage, the filter choke – against high-frequency noise, the varistor – dissipates impulse noise. Some models have 1 or 2A USB ports for charging gadgets. Surge protectors protect equipment, but they also cost enough, and are larger in size than conventional extension cords;
garden extension cords are similar in design to household extenders, but protected from moisture. These can be safety shutters, circuit breakers or fuses. Such devices are distinguished by a long wire – from 20 to 100 m, can be equipped with a pin for easy attachment in the ground. The only drawback of such extension cords is their size and inconvenience in storage.
For most of you, an ordinary household extension cord is suitable, but they are also different, therefore, first of all, you need to answer yourself a number of questions:
- What is the distance from the socket to the equipment?
- What equipment will be connected, what is its power?
- In what conditions will the extension cord be used?
- What additional functions should the device have?
In fact, the answers to all these questions are the main parameters for choosing an extension cord for the home.
Length of cable
The parameter that attracts attention first of all is the cable length. The longer the wire, the more freedom the user gets, because you can be at a sufficient distance from the outlet. When it comes to garages, terraces and summer cottages, this is priceless.
Remember that the longer the cable, the more power is lost, and if you connect a poor-quality or defective product, overheating may occur, and then the cable may catch fire or a short circuit.
A cable that is too long will be difficult to work with when the entire length is not required. We’ll have to wind it up, but at the same time it is worth remembering that the device can withstand the rated load only with an unwound wire. The manufacturer must indicate the maximum current with coiled and uncoiled cable.
At a construction site and in a garage, when an extension cord with a wire length of up to 20 m is purchased, it is better to use models equipped with a reel for reeling, but here you should be extremely careful. The fact is that when powerful equipment is operating, the wire will heat up, therefore it is better to buy extension cords with fuses – they protect against overload.
At home, when connecting powerful equipment, it is better to unwind the wire to ensure the best heat dissipation. It is believed that heating the cable up to 650C is permissible, but just imagine what could happen if the turns of such a heated wire touch each other! The insulation will begin to melt, and there it is not far from the circuit.
On sale you can find devices with a wire length from some 0.5 m to 50 m and even more. The optimal length of the cable in the extension cord for domestic conditions is from 3 to 7 m.
Wire size and maximum load
These two parameters are in direct proportion to each other: the larger the cross-section of the wire, the more load it can withstand. A simple analogue is the diameter of the water pipe. The more consumers, the larger the pipe must be in order for everyone to have a normal head.
Extension cords are made from standard wires, therefore the following cross-sections are possible:
0.75 mm2 – designed for current up to 6A or voltage of 1380 W. An excellent option for lamps and chargers, as well as modern TVs – they have low power;
1.00 mm2 – conducts 10A current, voltage 2300 W. Suitable for connecting not particularly powerful household appliances and tools
1.5 mm2 – designed for a current of 16A, a voltage of 3680 W. Can be used with a washing machine, heater, any household construction equipment;
2.5 mm2 and more – extension cords required at a construction site and in industrial conditions are suitable for connecting powerful devices and equipment.
For rough calculations, you can use the following rule: 1 mm2 wire cross-section can withstand a current of 10 A.
There are even extension cords with a core of 0.5 mm2, but it is strictly not recommended to include something more powerful than a table lamp in them. For home conditions, it is best to take a device with a wire of at least 1.5 mm2, so that it is a more or less universal device with protection from fools, since there is always someone who does not look at the maximum load and connect a powerful heater to the extension cord.
Extension cords with a wire of more than 50 m must have a cable with a cross-sectional area of at least 2.5 mm2.
Information about the cross-section of the cable can be found on the wire itself – it is marked accordingly. As a rule, the outer diameter of the wire indicates the cross section, but there are exceptions. One thing is clear – if a thin cable leads to the outlet block, then it is better to connect low-power electrical appliances.
First, think about what devices you are going to connect, and then go buy an extension cord. We recommend taking with a margin, since in the future more powerful devices may also be included in the list of connected devices. Please note that if the extension cord can withstand 10A, this does not mean that a 10A device can be inserted into each outlet. This is the total load.
What happens if you exceed the permissible load? The wiring may heat up and begin to melt, burn out the connection points of the wires, as a result – smoke and fires.
The type of wire is selected depending on the conditions in which the extension cord will work. Among the most common options are:
PVA – the wire has a plasticized PVC sheath, copper cores, round cross-section, is inexpensive, which affects the final price of the extension cord. The material is afraid of negative temperatures, dulls in the cold, and is also subject to abrasion. For domestic conditions, when the extension cord is not particularly pulled or frozen, this type of cable is perfect. Another disadvantage is sufficient massiveness, but it becomes critical when the cross section of the core is more than 2.5 mm2;
Ball screws are used much less often, they have a flat cut. Due to the thinner insulation, the cable takes up less space. Suitable for living conditions, but under heavy loads, for example, at a construction site, it may not withstand and become unusable;
KG (flexible cable) is suitable for harsh conditions. The core insulation and the cable sheath are made of rubber. Such a cable can withstand frost and heat, is resistant to mechanical stress, therefore, for difficult building conditions, this is the best option. However, such a wire should not be left in direct sunlight for a long time.
Number of sockets and plug type
The number of outlets varies from 1 to 4, or even up to 5-6. So many sockets are made not so that you can use 4-6 devices at once, but so that you can insert the plug and not remove it for a long time. Free nests still remain. Thus, both the extension cord and the wire of the appliance will last longer.
Don’t go chasing a lot of outlets – get the one that suits your needs. If you are going to connect only one device, then it makes no sense to take an extension cord for 4 sockets.
Pay attention to how the plug-in contacts are located. The most convenient location is diagonal. In other cases, it can be problematic to connect two devices to adjacent sockets.
Have you examined the outlet block? It’s time to look at the extension plug. Give preference to molded forks, which are more reliable and safer. In addition, such forks are more difficult to manufacture, so it will be more difficult to run into a makeshift extension cord in this case.
Grounding is a useful option that will reduce the risk of electric shock when operating a faulty electrical appliance, as well as reduce the level of interference in equipment connected to the same network or located nearby. The grounding conductor is especially important when connecting a washing machine and refrigerator to an extension cord. True, grounding will be relevant only when the apartment is connected to the ground loop.
What else do you need to know?
When considering an extension cord, pay attention to the following parameters:
level of protection against dust and moisture. For home use, products with an IP20 protection level are chosen, they are not resistant to high humidity and dust. If an extension cord is needed for work outdoors, in a garage, in a bathroom or at a construction site, look towards models with an IP44 protection level;
protective shutters on the sockets will become an additional obstacle to moisture and dust penetration. They will also be useful in apartments where there are children;
the shutdown button will allow you to de-energize all devices without removing the extension cord itself from the outlet. Do not confuse this supplement with overvoltage protection. The off button does not make the power strip a surge protector.
And finally, a few examples of choosing a suitable extension cord:
- to equip a workplace with a computer (laptop or monitor with a system unit), a printer, speakers, a router, it is better to take a surge protector with 4-5 connectors. An additional USB connector comes in handy too;
- for working with a construction tool, for example, a drill or screwdriver, the most common extension cord with one socket is suitable. It is more compact, easier to carry, and the adjacent sockets will not get dusty;
- for a living room where you need to connect, for example, a TV, a lamp and a pair of chargers, the simplest extension cord (if you have a grounding conductor, take the appropriate device) with the number of sockets you need. It is better to take the section with a margin, since sooner or later someone will need to turn on a hairdryer or a heater;
- for giving, if you plan to use a lawn mower, an extension cord on a reel is best suited – its long wire is neatly coiled into rings and fixed, and the extra length will not interfere with the work. Such a device is also suitable for a garage, if it is necessary to turn on a welding inverter. Just be careful not to overheat the tightly coiled wire.
In conclusion – a helpful video, where you will find some more tips for choosing an extension cord.