Overhead sockets: varieties and their characteristics, connection and installation, use of grounding

An integral part of any modern room is power supply. To organize lighting, the installation of a switch is required, but most electrical appliances are connected using electrical outlets. Wall-mounted sockets are more convenient and attractive. However, if the wiring is open or additional power points are needed, and there are not enough standard installation locations, overhead sockets are used.

Varieties and their features

Sockets are parts of a wide variety of plug connections. These are not only power electrical appliances familiar to most, but also connectors for:

• radio point;
• phones;
• audio and video playback devices;
• computer networks.

There are many devices that are connected through special sockets. Most often, however, the outlet is associated with the electrical network.

According to the type of wiring, sockets are divided into two main types:

1. For hidden wiring - used in rooms with power cables located inside the walls. For fixing the sockets, regular places are provided to which the power cables are connected.
2. For surface wiring - usually used in the absence of pre-wired hidden wiring. Modern life often requires the simultaneous connection of a large number of electrical devices at the same time. For this purpose, you can use all kinds of splitters. But it is most convenient to organize the installation of additional sockets at the places where consumers are located. It is difficult to grind walls for laying hidden wiring and prepare seats for new sockets. Therefore, in such cases, they often resort to laying separate sections of open wiring to overhead sockets.

Device and materials used

Modern industry produces both simple devices and devices with an extended set of functions. However, the basic design of all outlets is the same. A typical model contains:

• A block with electrical contacts designed to fix the plug. The contacts have fasteners for connecting a power cable.
• Protective housing that can cover the block mounted on the wall or be fixed on the wall itself. In the latter case, the block is located in special seats inside the body.

The shoe is the most important and crucial structural element. Reliability and safety of operation depend on its properties. When choosing an outlet, you should pay attention to material from which the block is made:

• Ceramic is the safest material, has unmatched temperature resistance and excellent insulating properties. The disadvantages include fragility, with rough handling of the outlet, the ceramic shoe can crack.
• Carbolite was widely used along with ceramics. Provides high insulating properties, tolerates temperature effects well, has less fragility. Currently, it is used extremely rarely.
• Cheap plastic - suitable only for low currents, not able to withstand high temperatures, rather fragile. It is found in products of the lower price range.
• Polycarbonate or other thermoplastics are the main material for modern outlets. Resistant to high temperatures, does not support combustion, has sufficient mechanical strength.

The vast majority of modern outlets contain a ceramic or polycarbonate block.

The first one is recommended to be used when connecting devices with high power. The second will be more durable, therefore it is recommended for options that require frequent switching on and off of devices.

The contacts of an electrical outlet are just as important as the connector itself. Most common the following varieties:

• Plate elastic contacts made of conductive material. Brass is used more often, steel is used in cheap products. Over time, low elasticity and significant bending loads when the plug is turned on and off lead to changes in the shape of the contact, the tightness of the contacts to the pins of the plug is lost. Doing so can cause the outlet to overheat, spark or even fire. Despite significant drawbacks, such a design is used most often due to its simplicity and low cost.
• Contacts with pressure plate. The fork pin is pressed against the contact plate by the force transmitted from the helical spring to the pressure plate. This design has increased reliability and durability, and provides the greatest safety. The coil spring is not subject to visible wear and remains functional throughout the life of the socket. The reliability of fixing the pins of the plug minimizes the possibility of overheating of the connection and the likelihood of fire from elevated temperatures and the formation of sparks. The cost of sockets with a similar design of contacts is slightly higher, which is explained by the number of elements in the composition of the contact.

Matters and method of connecting wires to contacts. The easiest to connect is the spring-loaded clamping method. However, it has low reliability and can lead to overheating. Screw contacts are much more reliable.

The classic screw and washer design can provide the best connection between pin and wire, but this will require additional manipulation. For maximum reliability, it is recommended to twist a loop with a diameter slightly larger than the cross section of the screw in the stripped section of the wire.

The screw should be unscrewed completely, then put a loop of wire over it, then screw in the hardware and tighten well.

Dust and moisture resistance

Modern models of sockets are tested for protection against dust and moisture. Protection indicators are reflected in the IP marking, which must be affixed to the product body. The marking consists of two numbers.

The first means security from extraneous mechanical penetration:

• The number 2 means that it is impossible to touch the socket mechanism with your hands.
• Number 3 indicates that the inside of the product cannot be penetrated with a tool.
• Number 4 indicates the impossibility of wire penetration.
• Figures 5 and 6 show that the penetration of dust inside the case is completely excluded.

The second number indicates the security of the product from moisture:

• The numbers 1 and 2 mean that the outlet is protected from drops vertically falling on the body.
• Number 3 indicates that the device is protected from rain.
• The numbers 4 and 5 indicate that the device is protected from direct, strong splashes of water.
• Number 6 indicates that the housing is protected against water jets.
• The numbers 7 and 8 assume that the device can be completely immersed in water.

These indicators must be taken into account when installing outlets in rooms with increased dust or humidity. This is especially true in the kitchen and bathroom. When installing outlets outdoors, it is recommended to select devices with the highest levels of protection.

Electrical characteristics

In our country, a single-phase electrical network with a voltage of 220 V is used to power most electrical appliances. It is important to pay attention to the voltage markings on the body of the outlet. The operating voltage range of 220-230 V is often indicated. This is a perfectly acceptable option. However, devices labeled with 250 V are more reliable and more resistant to voltage surges.

The rated current is the most important characteristic of the socket. The total power of devices that can be connected depends on it. The most common models are designed for currents from 10 to 16 A. Practice shows that even the cheapest specimens can be labeled 16 A, so evaluate this the parameter follows in conjunction with the build quality and materials used to make the pads and contacts. To connect powerful consumers, it is recommended not only to focus on the specified rated current, but also to choose the most reliable models.

Number of contacts

A single-phase household outlet may have two or three contacts. Phase and zero are required. The phase conductor transfers current from the power source to the load. When the device is operating in a single-phase network, the current in the neutral conductor is equal to the phase current.

The third can be a grounding contact. It is designed for connection with non-current-carrying parts of the connected device and performs the functions of a protective neutral, to ensure leakage of current to earth if it occurs on the case or other areas that may be touched human. For the convenience of users, both single and double surface-mounted sockets with grounding and models with a large number of sockets are available.

If the electrical wiring is equipped with a protective neutral, you should always use only grounded surface-mounted sockets.

Installation procedure

Like other elements of open wiring, overhead sockets are easy enough to install yourself. To do this, you can use with the following algorithm:

• Disconnect the power supply. This is the key to ensuring the safety of all work. If you are not sure which machines are responsible for disconnecting the corresponding line, it will be useful to check the absence of voltage with an indicator screwdriver.
• Partially disassemble the socket. To do this, you need to separate the body from the shoe. Depending on the design, you will need to unscrew the fastening screw or disassemble the case and remove the block.
• Mark up and fix the socket on the wall. The device is attached to the wooden base with self-tapping screws. Dowels should be used for concrete and brick walls. The device can be screwed to a drywall sheet with self-tapping screws or special plastic fasteners can be used.
• Prepare a hole for the cable in the socket housing. The hole can be protected by a special elastic plug, in which several optimal diameters are provided. The selected hole is carefully cut with a knife. If there is no such plug, then the hole breaks out in the plastic case along the outlined contour. For greater accuracy, you can take a file and cut a hole of the required size, which corresponds as much as possible to the section of the cable used.
• Strip the wires to the required length, which is selected based on the design of the terminals on the contacts. This operation must be approached responsibly. The presence of significant stripped areas protruding beyond the attachment is not allowed, as this can lead to a short circuit. Stripping to a shorter length is also unacceptable, since parts of the insulation getting under the retaining clip can lead to deterioration of contact, overheating of the connection, melting of the block or fire.
• Connect the wires to the clamps. The phase and neutral wires in domestic sockets are connected in random order. If the wiring has a protective neutral, the wires are usually color coded. The phase is marked in white or brown, zero in blue, and ground in yellow or green. If there is no color marking, then the task becomes much more complicated, because only the phase can be determined with an indicator screwdriver. In this case, to determine the protective neutral, you need a multimeter and a guaranteed grounded element, for example, a steel bath. When measuring, one probe of the tester touches the body of the bath, and the second closes to one of the three wires. In voltage measurement mode, the phase wire will show a potential difference of 220 V, the neutral wire - from 0.5 to 6 V, and the protective neutral - 0 V.
• Assemble the socket, turn on the voltage and check the operation.

The use of overhead sockets for open wiring does not lose its relevance. Even with hidden wiring, this is the only convenient way to organize additional power points. Careful selection of a quality model and competent installation will create a reliable and safe power supply system.