Metal pipes for wiring: see, application, specifics
Metal pipes can now be used for various purposes, one of which is electrical installation. The most difficult and important stage of cable laying is compliance with fire safety standards and requirements, especially, if there are wooden structures. Metal pipes for wiring can reliably protect communication networks from mechanical damage, as well as aggressive environments.
Open wiring in metal pipes can be an original solution for decorating the room
Types of channels for wiring
The choice of tube material depends on the type of room, where the wiring is performed, its conditions and features. Among the main materials of the channels for such purposes are distinguished:
- plastic;
- steel;
- copper;
- brass.
Polyvinyl chloride is used to make plastic models, polyethylene (P) high (V) low (N) pressure (D). PVC products are the most popular due to their affordable price, good indicators of heat resistance and strength. Common diameters - from 1,6 to 6,0 centimeters.
Plastic pipes have a smooth surface, which facilitates the work of replacing conductors, small mass, corrosion resistance.
pay attention! PVC and polyethylene channels are dielectrics, which allows you to consider them as an additional insulating circuit.
Thin pipes are used for laying wires, which are easy to bend
Metal pipes for wiring, made of steel, have a significant mass, however, they are characterized by particularly high strength. Such products are recommended for use in wooden buildings. Because the material is a good conductor, then, to ensure electrical safety, all such channels must be earthed. Thin-walled brass or copper tube is great for wall mounting, and for concealed gasket. It bends easily and does not always need decoration.
Some installation rules
Before installation of a cable route from metal thin-walled pipes for electric wiring, you should read the following rules:
- the ends of each segment of products require pre-cleaning from burrs and countersinking;
- the maximum allowable bending angle of the steel channel is 90 degrees;
- there is a limit on the length of the segments: to 10 meters in the case of a straight pipe, to 5 meters - if available 2 bends;
- performing a bend, it is important to monitor the integrity of the cross section of the product;
- the metal channel must be made as part of the SUP (equipotential bonding systems).
If it is impossible to fulfill the condition for choosing the length of the pipes, according to the rules, installation of an extended box without additional joints is required.
The physical essence of SUP is the need to connect all the leading parts into a single system as follows, to minimize or eliminate the potential difference between them. To do this, it must be included:
- earthing device;
- home (R) grounding (WITH) tire (Sh), mounted in the shield (SCH) accounting (IN) electricity (E) or input shield;
- all metal elements of the building structure.
If you follow these rules, then you can significantly facilitate the installation and replacement of wiring.
Features of copper and brass cable ducts
Copper products for production are not in high consumer demand due to high cost. Channels have the following features:
- compared to steel, no brass, no copper is prone to active corrosion;
- possibility of fast installation by own hands thanks to a wide choice of fittings and good bending features of thin-walled tubes;
- Carefully polished and open-mounted ducts can decorate the interior.
Copper pipes are not prone to corrosion, therefore, such a cable duct will not need to be replaced for a long time
in addition, copper / brass tracks are durable and resistant to the negative effects of external factors.
pay attention! Because these metals have good thermal conductivity, then they must be placed away from the heating pipes, otherwise there is a risk of insulation melting and wiring overheating.
Another disadvantage of choosing thin-walled cable ducts is the inability to provide them with reliable protection against mechanical damage.
Characteristics of steel pipes
Ordinary steel pipes are characterized by a greater wall thickness 0,25 centimeters. The value of this indicator for thin-walled steel products is in the range from 0,16 to 0,25 div. The use of metal pipes is strictly prohibited, if the surface of the aluminum wire is open.
Installation of thick-walled ducts for electrical wiring of steel is usually performed by welding and is expensive. Such products are relatively inexpensive, almost completely impervious to temperature changes and have high strength.
Steel pipes have an aesthetic appearance and without additional processing - polishing or painting
Manufacturers offer galvanized cable ducts for wiring. In other cases, additional treatment by painting or varnishing is required. With a horizontal arrangement to protect the pipe from condensation, it is recommended to form a slight slope towards the junction box.
Because the steel is thermally conductive, then the structure should be protected from extreme temperatures. This requires providing a distance of at least 50 millimeters between the routes of heating and wiring at their intersection. The distance from the cable duct to the heating system when placed in parallel should be greater 10 div.
In the open space, the steel pipe is fastened with special clamps or pads through each 250-300 centimeters.
Advantages of metal cable channels
The main advantages of metal ducts for wiring are:
- reliability;
- durability;
- practicality;
- variety of solutions;
- stability of parameters;
- resistance to UVA;
- resistance to low / high temperatures.
Resistance of metal pipes to damage allows to lay them openly without additional protection
Metal cable ducts are able to provide stable protection of wiring from moisture, rodents, mechanical effects and temperature changes. They can be used for a long time, especially, if covered with a protective layer. Such pipes do not require special maintenance.
pay attention! Wide variety of lengths, diameters, visual parameters and other characteristics of metal products allows you to easily choose the channels for wiring, which meet all consumer requirements.
Metal pipes do not change the size and shape in compliance with the rules of operation, suitable for both hidden (internal), and for the open (external) carrying out, and can also be used in unheated rooms.
Subtleties of using products
When using metal pipes, some difficulties with the drawing of wires in them are possible. There are several ways to do this. The simplest way is to pull a steel wire into the channel, attach the cable to its edge and pull it inside.
If the product has a significant length, then you can insert a ball with a tied thin, but with strong thread or tape. Talc is used to facilitate movement. A steel wire is attached to the end of the thread / tape. Next, insert the air compressor pipe into the hole and turn on the equipment. Under the action of pressure the ball moves on the channel for wiring, pulling the thread behind him. Cut the product with a hacksaw or a Bulgarian.
Pipes of different diameters are used for different wiring segments
Products with a diameter are usually chosen for switches and sockets 20 mm; for lighting fixtures - 1,6 cm; for connections between floors - 4,0 cm; for connecting switchboards or boxes - 25 mm. The length of the channels is usually 3-5 m.
If the room is characterized by high humidity and the likelihood of chemicals, then you can use thin-walled tubes with a diameter of about 20 mm, connecting them with threadless couplings. At a high level of dangerous factors it is better to take water and gas products with a diameter 15-80 mm, joining them with threaded couplings.
Important aspects of grounding
The main task of protective earthing is to ensure human safety from contact with electric current (ET). Its influence is manifested as follows:
- at current 0,6-1,5 thousand. mkA the effect of current on the body is felt;
- at 2-4 thousand. mkA - fingers begin to tremble;
- at 5-7 thousand. mkA - hand cramps can occur;
- at 10-15 thousand. mkA - it is difficult to open a hand with the conductor independently without the help;
- at 20-25 thousand. mkA - severe pain, breathing is difficult and it is impossible to separate the hand from the wire;
- at 50-80 thousand. mkA - heart failure occurs, respiratory paralysis occurs.
Critical current, causing heart fibrillation and respiratory arrest - 100 thousand. mkA. 1 mkA is a millionth of an ampere.
pay attention! Currents in the wiring (household) can have values of several tens of Amperes.
Any electrical system must be equipped with a safety cut-out device
In relation to the conductor of the permanent stand or phase conductor, the earth has zero potential, which explains the use of grounding. The resistance value of the earthing device, equal to the ratio of the voltage across it to the current, which goes to the ground, should be no more 4 Ohm.
Modern wiring is performed only with the use of a protective shutdown device, almost instantly triggered by any leak (unauthorized) current. There are the following types of grounding systems: TN-C, TN-SHO; TN-C-WORLD; TT; IT.
Decryption of letters in the first position: T - grounded neutral IP (power supplies); I - all current-carrying elements of the equipment (in t. h. neutral working wire) isolated from the ground. The characters in the second position mean: N - open conductive elements of grounded devices are connected to the neutral of the IP; T - conductive parts of appliances and electrical installations are grounded by a separate circuit. Letters through a hyphen: C - The functions of the zero protective and zero working conductor are combined in one conductor; S - operating and protective zero are provided by different conductors.
Metal corrugated pipes and smooth types of such pipes are perfect for laying hidden communications. Although today more and more alternative corrugated or smooth polymer cable ducts are used, steel / copper products exceed their characteristics in the degree of mechanical strength and security.
