In the installation cost, the most difficult is the building electrical, why? From the distinction of cables and wires to separate calculations, from electrical bridges to climbing wall wiring, from lightning protection grounding to weak current intelligence, each link is more complex and difficult to understand. Let's learn together.
1
10kV high-voltage overhead entry device
Suspension insulator XP below 10 kV, measured in "strings";
Outdoor high-voltage fuses below 10 kV WR, measured in "groups";
Steel through plates, measured in "blocks";
CLB of 10 kV or less wall conduits, measured in "pieces";
Arrester FS below 10 kV, measured in "group";
Indoor and outdoor support insulator ZA below 10 kV is measured in "unit";
Brackets and fittings are calculated in "kg".
2
Substation and distribution devices and equipment
Calculated sequentially from the entry device
3
Transformer installation
Calculation rules: according to different voltage levels, different capacities and different types, they are measured in "units".
TM installation: excluding transformer oil withstand voltage test and transformer system commissioning.
TM classification: the cooling method is oil-immersed and dry; The number of phases is divided into single phase and three phase; The coil material is divided into copper and aluminum coils; The iron core is divided into hot-rolled and cold-rolled silicon steel sheets.
4
Installation of power distribution units
Circuit breaker (QF), load switch (QL), disconnector (QS), break and turn on the normal load circuit, protect and control high-voltage electrical equipment. The installation includes equipped with electromagnetic, spring energy storage, manual and other operating mechanisms.
Current transformers (TA) and voltage transformers (TV) are used to measure voltage, current, electrical energy and relay protection.
Calculation rules: The above devices are measured in "units".
5
Busbar installation
Busbar: There are high-voltage busbars for power transformation and distribution devices and low-voltage busbars for workshop power distribution, pay attention to the difference.
常用硬母线：铜(TMY)、铝(LMY) 。
Calculation rule: Calculation of monolithic "extension meters".
L Female = (Length of single piece extension meter of bus design + reserved length of bus bar) × (1+2.3%)
Loss of production and installation – 2.3%
6
High voltage control equipment
High-voltage consoles, cabinets, and screens are used in power plants, industrial and mining enterprise substations (institutes), and are the main equipment for receiving electricity and large-scale high-voltage AC motors for starting and protection.
At present, there are three kinds of domestic products: fixed, handcar and movable. Models include GG, GFC, GBC and so on.
Calculation rules: respectively according to the control panel, relay screen, analog screen, power panel, DC panel, console and box-type power distribution room and so on in "sets".
7
Low-voltage control of power distribution equipment
Calculation rules: complete sets of power, lighting control and power distribution cabinets, boxes, screens, etc., regardless of model, specification and installation method, are measured by "sets".
When the wires in and out of the cabinet, box and screen need to be welded (pressed) terminals, they are measured in "unit".
High-voltage and low-voltage equipment bases and brackets: slot (angle) steel bases and brackets are calculated according to "kg" and "m".
8
Power and control cables
Cable burial or trench entry into the house
L＝(l1+l2+l3+l4+l5+l6+l7)×(1+2.5%)
9
Installation of power and control cables
Calculation rules: power and control cables below 10 kV; Regardless of the laying method, the parts are calculated as "m".
The length of the cable is expressed in the way and part of the laying: cable length = (2× end length + lead up and down length + straight buried length + cable trench length + protection pipe length + steel cable length + wall length + shaft road length + bridge length + groove frame length ten ladder length + line length etc + cable reservation) × (1 + 2.5%) cable ends: production and installation are measured by "one".
10
Cables are laid directly buried
Cable trench earthwork, calculated in "m³":
V=S L, the length of the trench for each 1 m of the two cables, and V=0.45 m for each additional cable, 0.153 m³ for each additional cable. Cable trench sand cover brick: calculated by trench length "m".
11
Cable trench laying
Cable trench: into the people, not into the ditch.
Trench masonry: earthwork volume "m³"; Laying bricks or pouring "m³" at the bottom of the trench and on the wall; ditch wall, bottom plastering cement mortar "m²"; Groove cover plate made "m³"; Value at the time of purchase and shipping costs.
Refer to the "Construction Project Budget Quota".
Peel and cover the cable trench cover plate: "m" calculation;
Trench support system safety: steel "kg", concrete "m³" calculation.
12
Cable tray installation
Bridge frame: divided into ladder type, tray type (perforated tray, non-perforated tray), generally composed of straight sections, bends, tees and other accessories and supports, hangers, etc.
Calculation rules: Regardless of steel, stainless steel, aluminum alloy, glass fiber reinforced plastic, and plastic bridge, they are calculated according to "m". Including the bridge, each section is connected with 5.5~16mm² of electrical communication
Installation of jumper wires and grounding wires and grounding terminals.
13
Piping engineering quantity
Rules: The piping is calculated according to the "extension meter" according to the different pipe materials, specifications and laying methods (light and dark), and the length of the junction box (box), lamp head box and switch box is not deducted.
Essentials: Calculate circuit by loop from the distribution box. Method: Horizontal pipe, calculated by the size of the wall and column axis of the building plan. Pipes that can only be laid diagonally can be measured with a scale bar when the scale of the drawing is correct.
14
Light and dark boxes for piping and wiring
Wiring (branch), socket, switch, lamp head and other boxes are measured according to "unit".
15
Electrical wiring
Rules: Lighting and power circuits are calculated according to "single-line extension meters" regardless of variety, specification, model and laying method.
Pipe threading length = (piping length + reserved length of wire) × Number of wires of the same cross-section
Commonly used wires: single-core, multi-core; Aluminum core, copper core; Plastic, rubber insulation.
Wire reserved length