There are models whose shell is adapted for use in conditions of negative temperatures - such products are specially designed for installation outdoors; in terms of wear resistance, they are noticeably superior to their analogues. We are talking about SIP and KG, modifications with shells that provide the best protection current-carrying conductors.

The problem of using wiring in the cold

It is often forgotten that cable and wire intended for use inside buildings are not suitable for use in open spaces. Because of this, many people make the mistake of bringing internal wiring to the street if it needs to be stretched from one building to another.

Under conditions of temperature changes, the cable sheath quickly wears out. The VVG and ShVPP wires are most susceptible to this: already at a frost of 15 degrees, the vinyl insulating coating of these models becomes unusable. Vinyl hardens so much that any attempt to bend or straighten the product may result in its destruction.

A little best qualities has the VGG model. Although it was originally developed for indoor installation, its use outdoors is permitted in regions with mild winters, where the air temperature does not fall below 25 degrees. In central Russia and the north it is no longer suitable: its shell is made of PVC and becomes tanned in extreme cold. This is not surprising, since the VGG was originally developed for use in enclosed spaces.

The best solutions for arranging street wiring

For outdoor use, special cable models have been developed - these are KG and SIP. The first modification is a soft rubber wire that partially retains flexibility at temperatures up to 40 degrees below zero. The product is designed for installation industrial installations, but it can also be used in everyday life. The KN modification with the CL marking has the highest plasticity indicators. This model is used in the most severe conditions.

SIP has best performance mechanical strength. Its insulation is made of cross-linked polyethylene and provides maximum protection for live wires. True, SIP is only suitable for connecting branches and individual inputs to power lines. This wire is a worthy alternative to non-insulated aluminum cables, which were previously used for this purpose.

The SIP markings contain numbers indicating the number of cores. The KG cable can also have several cores - from 1 to 5. If we compare both types of wires, then the KG is better suited for arranging street wiring - SIP is strictly specialized, its installation is carried out using special fittings, anchors and clamps.

The extension cord is the same necessary element electrical wiring in the house, such as sockets, switches and other equipment.

You can find dozens of their varieties in the store. Which one to choose and what parameters to pay attention to first.

Wire length and number of sockets

Remember that the longer the carry, the greater the voltage loss will be. For household appliances, the optimal length of the extension cord is from 3m to 7m.

At the same time, you can connect a load with a power of no more than 3.5 kW (up to 16A) at the same time. It depends on the cross-section of the wire.

The contacts of the sockets are simply not designed for more, no matter how thick the wire turns out to be.

By the way, many sockets for sockets are not needed for simultaneous connection large quantity devices, but in order not to constantly pull out the plug, thereby protecting the contacts from loosening.

Wire cross-section and grade

Select the wire cross-section for connecting the load of room equipment (TV, computers, refrigerators) to at least 0.75 mm2.

Many people do not know, but all extension cords must be manufactured and comply with GOST R 51539-99 (IEC 61242-95). It is called "Extension Cords for Household and Similar Purposes on Cable Reels." You can download it.

Here are the regulated wire cross-sections for extension cords in accordance with this standard:

The type of wire is most often PVA with polyvinyl chloride insulation.

In this case, it is advisable to have the diameter of the wire itself (not a separate core) from 5 mm and above. If this is not the case, the manufacturer most likely saved on something - either on copper or on insulation.

The KG brand can also be used instead of PVA. It is more resistant to negative temperatures and changes in weather conditions. For street or garage use, this choice would be more correct.

Drag the PVS several times concrete floor, and his isolation will end. KG is more resistant to such operating conditions. Other cable brands are also applicable:

Here are the suitable wire sizes for quality carriers, and that they can be safely turned on without the risk of overheating (refrigerators, washing machines, TV, drills, grinders, heaters, etc.):

Unfortunately, you will almost never find factory-made household extension cords with a cross-section of 2.5 mm2 in stores. Unless it will be reels or reels of great length, from 50 meters and above.

Therefore, such models (with wires 2.5mm2, 4mm2 and higher) are often made independently.

For more powerful devices, such as inverters welding machines, a completely different class of products is coming.

Mechanical protection

A high-quality model must have protection against pulling and bending of the wire.

This applies equally to both the connector with the plug and the place where the conductors enter the extension cord housing.

Never operate a carrier with twisted wires. Firstly, this will sooner or later lead to damage to the cores, and secondly, such a cable will simply heat up.

Please note that extension cords can only withstand their rated load when the cable is completely unwound. On the case, sometimes special symbols are applied, with the maximum current when the wire is wound and unwound.

Before buying an extension cord, look at what kind of plug it has:

If the fork is not cast and can be disassembled, then there is a risk of running into a dubious product. These are the easiest forks to make using a homemade method.

To produce solid ones, you at least need some professional equipment.

In addition, if your equipment has a plug without a Euro socket, then an extension cord with a Euro socket is contraindicated for you. The use of Euro adapters and adapters in this case increases the contact resistance several times.

It also disrupts the grounding system, which can lead to electric shock. It is simply dangerous to connect some devices and tools without grounding.

The transition resistance of one contact in the new model should be no more than 0.05 Ohm. During operation, it can deteriorate to 0.1 Ohm.

That is, with a rated load of 10A, only on the plug-socket contacts alone you can lose up to 10W of power every hour. Here is a summary of voltage and power losses in extension cords depending on the length, material and cross-section of the cores.

And this is with standardized values. What happens if you stick various adapters in?

Also pay attention to the location of the plug-in contacts of the sockets. They must be made so that the plug of the connected device is inserted diagonally or obliquely, and not vertically.

Otherwise, it will be impossible to connect the second plug to the adjacent socket.

Strive to choose models with built-in surge protection and protection from dust and moisture. Moisture resistance is indicated in Latin letters IP. Household extension cords most often come with IP20 numbers.

They can only be used in dry and dust-free rooms, but not in the bathroom or garage. Models with IP44 protection already have dust and splash protection.

Do not confuse models of surge protectors and simple carriers with a shutdown button. The latter have a built-in switch designed to manually turn off the power.

It in no way protects the equipment from voltage surges and imbalances. To do this, there must be at least a varistor inside the case. What this is will be discussed below.

By the way, the switches themselves are different:

It is better to choose 4-pole networks. It's quite easy to distinguish them.

Four-pole is twice as wide. It is he who breaks both phase and zero.

With two-pole you can only turn off zero core, and the phase will continue to flow to sockets and devices when the plug is plugged in.

Be careful!

Internals of extension cords

One of the most common types is the so-called computer extender or surge protector. It has a built-in switch in the case that can be used to turn off the power to all outlets.

It is usually designed for a current of 10A (power 2.2 kW). Each socket in them has a grounding contact. Which is extremely necessary for apartments with three-wire wiring (phase-zero-ground).

The supply wire on high-quality models must be marked. The brand and core cross-section are stamped on it.

Do not buy carriers where the cross-section of the wires is less than 0.75 mm2 or where there are no identification marks on the wires at all.

However, you should not particularly trust the thickness of the cable itself. It is quite possible that the insulation in it will be quite thick, but the veins will be very thin.

Such a wire will definitely heat up, even with minimal load.

The most important thing in such models is that there is not just a switch inside, but an “automatic machine” that will automatically operate when the load is exceeded.

This extension cord is used to power computers, LCD and LED TVs, printers and other household appliances.

How does it protect equipment from voltage surges? In order to understand this, you need to look inside the case.

To do this, unscrew the screws on back side and remove the cover. The contact pads of the carrying sockets must be made of brass plates.

Most of them are 0.3mm thick. Higher quality models for high currents have a thickness of up to 0.6mm.

In cheap Chinese counterfeits you can find not brass, but just iron plates coated with brass. You can check this with an ordinary magnet. Non-ferrous metal will not be magnetic, but iron will easily.

In addition to worse conductivity, the iron contacts after the first use of a wide Euro plug will expand and will not return to their reverse state. Brass has significant elasticity.

By the way, many “Soviet” plugs will not fit into such connectors due to the presence of side grounding pins.

The most important element that protects all connected equipment is a varistor. Phase and zero approach it from both sides. With a short-term voltage surge (about 300V), its resistance drops sharply, but the current flowing through it increases.

Due to this, the voltage on the varistor itself is stabilized. If the surge is not short-term, but the overvoltage occurs constantly, then it simply closes the circuit and an artificial short circuit is created inside the case.

That is, if the voltage in the sockets jumps and remains within 300V, the varistor sharply decreases internal resistance(down to zero), it is triggered, creating a short circuit.

And it is from this that the short circuit is disconnected circuit breaker, protecting all connected devices.

Higher quality products are equipped with several varistors, plus capacitors and inductors.

In inexpensive ones, all protection ends with a varistor and a circuit breaker or push-button fuse.

The plates themselves are not spring-loaded, although they are brass. And at relatively high currents they burn out quickly.

Extension cord without switch

For more powerful loads, you can choose models without built-in switches. Protection in this case must be provided by automatic devices in the panel.

Choose such models for garages and cottages with a wire cross-section of at least 2.5 mm2, since socket groups are often protected by 25A circuit breakers.

And if an extension cord made with a 0.75mm2 cable is overloaded, no machine in the switchboard will work. The extension cord will start to melt first.

They also have brass contact plates inside them. Sometimes they are attached to a base made of non-combustible material. This is directly responsible for the fire safety of the entire block.

One such material is polyamide. In general, all manufacturers must make the extension cord housing from non-flammable plastic, but not all “Chinese” comply with this.

Power wires can be either soldered or welded resistance welding (best option), or simply tightened with screws in special terminal connectors.

It is more reliable when the clamping occurs with a plate, because very often these screws crush the tip of the wire, worsening the contact area and the contact itself.

If your carrier is made in this way, then it would be more advisable to crimp such wiring with an NShV tip.

Soldering may fall off at high currents and heat, but nothing will happen to the welding. Even during short circuits.

In addition to the contact brass plates, do not forget to check the plug itself with a magnet. It should also be made of non-ferrous metal and not be magnetized.

Bad extension cords

Unfortunately, most often there are cheap extension cords on sale, which hide a bunch of potential dangers.

In appearance, everything seems to look civilized, and the inscriptions are calming. Rated currents up to 16A, voltage 250-260V! etc.

However, once they are revealed, all the shortcomings are revealed. The most painful place is the undersized wire cross-section. You won't see this under the “thick” insulation and molded plug.

But inside the case, at the points of connection to the plates, you can already compare it with something.

Next come the magnetizable contact plates. This picture says a lot:

Sometimes they are even made from tin tin cans, as evidenced by the drawing on the sides. Instead of brass, galvanized iron is used here. As a rule, in such models the fork itself is made of the same material.

Even with a load of less than 1 kW, the wire begins to heat up, and with prolonged load it can melt. All this is fraught with the risk of fire.

Therefore, be careful when purchasing and never trust only inscriptions and brand names. You can choose a high-quality extension cord for absolutely any purpose with a length from 1.5 m to 50 m.