- Electricity plan and project
- Cable brands
- Cutting strobes, laying and protecting cables
- Junction boxes, electrical connections
- Wiring accessories
- Common mistakes and workarounds
Professional electricians have long defined a set of simple rules: what must be done and what must not be done in any case when installing electrical wiring. In this article, we will describe the main stages of installation and replacement of electrical wiring, and the most important rules regarding safe operation..
Electricity plan and project
Any electrical installation is carried out according to a pre-drawn up plan. Multiple wiring plans can be combined into a power project.
When drawing up a plan, the following is performed in turn:
- Determination of the place of entry of electricity to the local area.
- Determination of consumer connection points.
- Determination of the desired installation locations for switching and protection equipment.
- Drawing up a scheme for laying a cable between the input and consumers, taking into account the objects from clause 3.
An example of an apartment wiring plan: 1 – switchboard; 2 – introductory machine; 3 – automatic switches; 4 – one-key switch; 5 – sockets; 6 – two-button switch; 7 – lamps
In practice, the wiring plan is relevant only for individual rooms or adjacent areas. A more global electrification needs careful design, which defines:
- The best way to carry out electrical input to the object.
- The location of the input-distribution device in accordance with the TU energosbyta.
- Placement of intermediate panels according to network configuration and load distribution scheme.
- Drawing up a plan for the transmission of electricity from the main entrance to key nodes.
- Drawing up an electrical installation plan from each key node.
- Selection of the optimal brands and cross-sections of cables for each line between the nodes. Optional – choice of cable sheath.
- Selection of protective devices and drawing up wiring diagrams.
Do not underestimate the capabilities of the project. In particular, it allows you to:
- Best match wiring with other work steps.
- Avoid waste of materials and the appearance of illiquid leftovers.
- Provide for any specific conditions at the site.
- Calculate the power of the network and its components in advance.
It is the cornerstone of quality installation. For stationary wiring (which is attached to or inside walls), only cables with single-wire insulated copper conductors in general belt insulation can be used: VVG, PVVG. Depending on the safety requirements, a non-combustible (ng) or reduced smoke (ngd) cable can be used. This requirement is mandatory and categorical, it is prohibited to use any other cable in fixed wiring.
Flexible cords and wires (PVA, SHVVP) are used only for connecting non-stationary pantographs and household appliances. It is also allowed to use conductors of flexible wires and wire PV-3 to make jumpers in shields and boxes.
Cutting strobes, laying and protecting cables
To cut grooves in brick, concrete and plastered walls, you must use a special cutting tool with diamond discs for stone. The slotting tool is used only in hard-to-reach areas, but not everywhere. Thus, the width of the groove should be as small as possible, based on the width of the train and the fasteners.
The depth of the groove is selected 2–3 times the thickness of unprotected wires or 1 / 3–1 / 2 more than the diameter of the protective sheath. The cables are laid freely, without tension, the degree of their deepening in the strobe is checked with a spatula attached to the wall. Putting up the section of the groove is possible only after the final fixing of the wiring in this section, plus 1-1.5 meters on each side.
Cables can also be installed in an open way – without cutting a groove, but using special fasteners. In this case, the cables are pulled into a protective sheath in order to localize a possible ignition source. The choice between a duct, a corrugated tube and a metal hose is determined based on their fire safety requirements and the load on the line. The protective sheath can also be used in hidden wiring if the wires are laid inside false walls or walls made of wood, adobe, expanded polystyrene and other flammable materials.
Junction boxes, electrical connections
Junction boxes are installed at the branch points of the power and switching decoupling of the lighting lines. Any connection between two pieces of solid cable must remain audited. It is quite logical to want to use existing units – installation boxes and shields. But in switch boxes it is allowed to connect only the lines controlled by them, and in the socket box it is allowed to make no more than 2 inserts for the so-called. daisy chain connection. Taking all this into account, the wiring branching scheme is determined, the decision must also be justified from the position of economical consumption.
It is advisable to connect wires in boxes using spring clips. Soldered and welded strands cannot be disassembled and reconnected, and screw clamps can easily cut the core. As for the maximum load at the connection point, it cannot be higher than the nominal (taking into account the current-time characteristic) of the circuit breaker, which means that there is no need for a margin..
Electrical fittings (sockets, switches) are mounted last, and installation boxes for it are installed between the stages of rough and final wall finishing. A thin layer of putty on the sides of the boxes will not play a special role, but the decorative overlays will stick tightly to the walls.
Terminals on fittings are of two types: bolted (usually at sockets) and in a socket (mainly at switches). Only one core can be inserted into the socket. Any adjacent wire connections are made not in the terminal, but next to it, using a spring block. Under the screw clamp, you can attach two cores from different sides of the head, or one by twisting it into a P-shaped loop.
When installing fittings in a common frame, it is prohibited to connect lighting lines from the socket group. The group of outlets itself can be powered by one cable, from which jumpers are scattered, but only in one direction (no more than 2 wires per terminal).
Common mistakes and workarounds
The described working methods are strictly categorical and must be followed. Any other installation cannot be called technological and safe. But there are also hopeless situations, especially with fragmentary repair of electrical wiring or laying in difficult technical conditions. As a conclusion, we will provide some tips and solutions to some problems..
1. Strip the cores only with a stripper, cut off the belt insulation with a cable knife with a restraining heel. Due to the slightest notch in the copper wire, it will break off at 5-6 bends.
2. Shields are the most critical part of the power grid, assemble them correctly. If you are not sure if you can handle it, get a professional.
3. Aluminum wires are prohibited inside buildings..
4. The connection of the input (with aluminum conductors) from the overhead transmission line with the internal network occurs either through an automatic machine or by means of piercing clamps. Temporary connections are made with screw or spring terminals.
5. Copper cable is allowed to be bent with a minimum radius of six values of the cable thickness.