Thread Content
Small tips for reading electrical and plumbing construction drawings. Electrical and plumbing installations are an integral part of a house; their safety and convenience have a great impact on the comfort level of our living environment. Before starting the plumbing and electrical work, homeowners can take a look at the construction drawings, which will help them avoid many pitfalls. So, how do you read hydroelectric construction drawings? Next, follow the editor to take a look! http://img.civilcn.com/d/file/zhishi/gcgl/2020-01-13/0c55c6a8bfc54e3d6179d918dec7b0de.jpg So how should one read hydraulic and electrical construction drawings? I. How to read waterway construction drawings! http://img.civilcn.com/d/file/zhishi/gcgl/2020-01-13/4c34ea91cb4d6d2d6fe0362c2b5c76ad.jpg When reviewing plumbing drawings, it is essential to compare the plan view with the system diagram. This helps determine where pipes make turns, where their diameters change, where water distribution points are located, and what their elevations are. Additionally, when examining the water supply system, one must check whether there are corresponding drainage measures and water-using facilities in place. It’s also necessary to assess whether the arrangement of water supply points, drainage measures, and water-using facilities is reasonable. For instance, if a washing machine water supply point is included in the design, generally its elevation should be 1.1 meters above the finished floor level (subject to specific design requirements). Next, check whether there is a drain for the washing machine—specifically, whether it’s a dedicated washing machine drain. Also, see if there’s a trap in place. Once all these are confirmed, check for a power outlet for the washing machine: Is its location appropriate? Are the height and safety measures of the outlet adequate? When viewing plumbing diagrams, it is essential to have a strong sense of three-dimensional space; one should feel as though they are standing in the room, following the paths of the pipes. II. How to read circuit construction drawings! When looking at electrical schematics, one should first read the instructions: what is the installation height of the sockets, and does it meet safety requirements? Where is the distribution box installed, and what is the load capacity, is it reasonable? Is the size of the circuit breakers appropriate? What is the diameter of the protective tubes for the wires, and is the wiring arrangement proper? Is there a suitable match between the wires and the electrical devices they power? And what is the method used for installing the wire conduits? For lightning protection grounding, it is necessary to check whether the positions of the down conductors indicated in the grounding plan match those shown in the lightning protection plan. If they do not match, then it is important to determine where the transition occurs. It is also essential to know what level of lightning protection is being used, whether the size of the lightning protection mesh is within the specified limits, as well as the material and specifications of the down conductors and the materials used for steel bar splicing. More importantly, it is necessary to verify whether there are equipotential rings in high-rise buildings to prevent side lightning strikes, ensure local equipotentiality in bathrooms, and assess the effectiveness of soil grounding. Additionally, factors such as local water levels and geological conditions must be taken into account. Although there are many design aspects to consider, when looking at the plumbing and electrical diagrams and conducting further detailed analysis, it is necessary to assess the rationality and practicality of the design from a reverse perspective. When examining the construction drawings for plumbing and electrical systems in home renovations, it is also necessary to consider the civil engineering aspects: the size of the structural beams, whether the sizes of the embedded conduits are appropriate, what the building’s elevation is, and whether the installation of plumbing and electrical fixtures affects the usable height of the rooms. The room dimensions, wall dimensions, thickness of the raft floor, thickness of the leveling layer, whether the insulation is internal or external, thickness of the insulation layer, and thickness of the decorative layers on the interior and exterior walls – only with these details available can accurate planning for embedding, pre-arranging components, and manufacturing take place. http://img.civilcn.com/d/file/zhishi/gcgl/2020-01-13/382cff862d0f72317d28e24f2afa6603.jpg Meanings represented by various types of symbols: 1. Codes for wiring installation methods: PVC – installed using flame-retardant plastic pipes; DGL – installed using electrical steel pipes; VXG – installed using plastic cable trays; GXG – installed using metal cable trays; KRG – installed using flexible plastic pipes. 2. Codes for locations where wires are installed openly: LM – installed along roof trusses or the lower chords of roof trusses; ZM – installed along columns; QM – installed along walls; PL – installed along ceilings. 3. Codes for locations where wires are installed concealed: LA – concealed within beams; ZA – concealed within columns; QA – concealed within walls; PA – concealed within roofs or ceilings; DA – concealed within floors or ground surfaces; PNA – concealed within ceilings that cannot be accessed. The different wire thicknesses on the same drawing should be properly categorized, with too many variations not being advisable. Depending on their uses, lines can be classified into the following 6 types: (1) Thick solid lines: Used for main elements such as electrical circuits and primary circuits, as well as for visible contour lines and frame lines. ⑵Thick solid line: The main lines, branch lines, cables, overhead lines, etc., in electrical construction drawings are all drawn with a thick solid line. For example, add the letter F in the middle of a telephone line, and the letter S in the middle of a broadcast line. ⑶Thin solid line: secondary circuit, normal circuit. The base line of the electrical construction drawings (i.e., the architectural floor plan) should be drawn with thin solid lines, in order to highlight the electrical circuits drawn with medium solid lines. ⑷Dashed line: Used for axes, center lines, etc., such as the center line in detailed drawings for electrical equipment installation. ⑸Dashed line: Used for auxiliary lines, shield wires, mechanical connection wires, invisible contour lines, invisible wires, and lines for planned future extensions, etc. ⑹Break line: Used for the boundary line of a broken section. In addition, there are also various special types of wires commonly used in electrical engineering, such as telephone lines, grounding bars, television antennas, and lightning protection wires. Limiting symbols or textual symbols are added to the line diagram to indicate its purpose, thereby creating new line diagram symbols. For example: ——M—— is represented as a bus duct ； ——L——represents cable trays ——B——represents broadcast lines ； ——R — represented as the television cable — A — represented as the fire alarm cable ； ——F——is represented as a telephone line: http://img.civilcn.com/d/file/zhishi/gcgl/2020-01-13/8247391cc064aa7e63f3036762eea9c8.jpg (1) The ink-line diagram should use straight-style Fangsong font. The various letters and numbers written in the figure can be presented in italic form, tilted to the right at an angle of 75° from horizontal. When written in combination with Chinese characters, regular script can be used, but italic script is recommended for physical symbols. The thickness of the strokes in Chinese characters is approximately 1/15 of the character’s height. The thickness of the strokes for letters and numbers in various types of writing is approximately 1/7 or 1/8 of the height of the character. Various fonts should be arranged from left to right in an orderly manner, with clear strokes. Improper simplified and traditional characters should not be misused. It is worth noting that engineering drawings should not use too many fonts, even though some fonts are very beautiful. In engineering design, the requirements of standardization take precedence over aesthetic considerations; we should follow **drawing standards rather than acting according to personal preferences. (2) The dimensions indicated on engineering drawings are usually expressed in millimeters (mm); only site plans or drawings of very large equipment use meters (m) as the unit, so electrical drawings generally do not require dimension labeling. 5. The ratio of the dimensions of a figure on a scaled drawing to its actual size is called the scale. Both electrical wiring diagrams and system diagrams are schematic drawings that are not drawn to scale. But floor plans and the like are generally drawn to scale. The graphic scale of electrical engineering drawings shall be drawn in accordance with **drawing standards. Floor plans are usually drawn at a scale of 1:100; in special cases, 1:50 or 1:200 may also be used. The standard sequence is: 1:10, 1:20, 1:50, 1:100, 1:150, 1:200, 1:400, 1:500, 1:1000, 1:2000. The detailed drawing can have its scale increased appropriately. When copying drawings, the original scale must not be altered. The scale ratios specified for drawing are as follows: a scale identical to the actual object; scales of 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:10n, 1:1.5×10n, 1:2×10n, 1:25×10n; and scales for enlargement of 2:1, 2.5:1, 4:1, 5:1, (10×n):1, 6. In orientation drawings, it is standard practice according to international conventions to have north at the top and south at the bottom, with west on the left and east on the right, in order to indicate the location and orientation of equipment or structures. Sometimes, to make the layout of the drawing more reasonable, other orientations may be used; however, the orientation must be indicated using an orientation marker (compass). The orientation markers are as shown in the figure, with the arrow direction indicating true north (N). To indicate the wind direction patterns throughout the year in the area where the equipment is installed, wind direction frequency markers are often shown on the electrical layout diagram as well. It is created by plotting, in a certain proportion, the percentage of wind blows in various directions based on the average statistics over multiple years for a particular region. The wind direction frequency diagram resembles a rose, which is why it is also known as a wind rose chart. Figure 3-1 Compass 7. Elevation: Elevation can be expressed in two ways: absolute elevation and relative elevation. Absolute elevation is commonly used in outdoor electrical installation projects; it is a height measurement determined with the sea level off the coast of Qingdao, China, as the zero point, and is also known as altitude. For example, the absolute elevation of the pad for an outdoor power transformer in Beijing is 46.88 m. Elevations in architectural drawings are usually relative elevations. Generally, ±0.00 is set at the indoor floor level on the first floor of the building; values increase upward and decrease downward. In electrical drawings, the installation elevations of equipment are referenced to the floor level of each floor. For instance, the installation height for recessed lighting distribution boxes is 1.4 meters from the floor to their lower edge; for surface-mounted boxes, it’s 1.2 meters. Both measurements are based on the respective floor levels. 8. For the purpose of simplifying drawings, **relevant standards and certain design organizations have established fixed drawing styles for common materials, components, and construction methods; some of these also include textual symbols for identification. To understand electrical installation drawings, one must know the meaning of the symbols on them. In electrical drawings, legends that are uniformly stipulated are referred to as national standard symbols; those promulgated by relevant ministries and commissions are called ministerial standard symbols. Some other large design institutes also have their own internal supplementary regulations, namely the so-called institute symbols, or what are known as* conventional notation symbols. There are many types of electrical symbols, related to areas such as power supply, lighting, disaster reduction, and information systems in electrical design. This book only introduces some of the symbols commonly used in electrical construction drawings for building projects; these are listed in Appendix 3. The internationally accepted standard for graphic symbols is the IEC (International Electrotechnical Commission) standard. China’s new **standard graphic symbols (GB) are theoretically consistent with the IEC standards, and the national standard code is GB4728. For standardized General Electric symbols, their meanings are no longer explained in construction drawings. If non-standard symbols are used in the electrical design drawings, a legend table should be provided. Analysis of plumbing and electrical installation drawings—when examining such drawings, it is essential to have a strong sense of three-dimensional space, so as to be able to follow the paths of the pipes as if being there in person. ①Floor plans & system diagrams: When examining the plumbing installation drawings, it is essential to compare the floor plans with the system diagrams; this way, one can determine where the pipes turn, where their diameter changes, where the water distribution points are located, and what the elevation of those distribution points is ； ②Drainage & water supply facilities: When examining the water supply system, it is necessary to check whether there are corresponding drainage measures and water supply facilities, and then assess whether the combination of water supply points, drainage measures, and water supply facilities is reasonable ； ③Water supply point for the washing machine: If a water supply point is designed for the washing machine, generally its elevation is 1.1 meters above the finished floor level (as specified in the design). It is also necessary to check whether there is a drain plug for the washing machine, whether it is a dedicated drain plug for washing machines, and whether there is a trap. After that, it’s important to verify whether there is a power socket for the washing machine, whether its location is appropriate, and whether the socket has the proper safety height along with adequate safety measures. http://img.civilcn.com/d/file/zhishi/gcgl/2020-01-13/67c988a0393f877f35ef6c8b05180650.jpg Notes on plumbing and electrical installation drawings: Consider the civil engineering drawings as well – when reviewing plumbing and electrical installation drawings, it is necessary to take the civil engineering drawings into account as well. Does the size of structural beams, the size of embedded sleeves, and the building height have any impact on the usable height of rooms after the installation of plumbing and electrical facilities? The room dimensions, wall dimensions, thickness of the raft floor, thickness of the leveling layer, whether the insulation is internal or external, thickness of the insulation layer, and thickness of the decorative layers on the interior and exterior walls – only once all these details are known can accurate embedding, pre-arrangement, and manufacturing take place. Familiarize yourself with the design specifications: First, you need to be able to understand the legends and be familiar with the design specifications. Then, refer to the legends provided in the drawings while examining them. When reading the drawings, follow the sequence of inlet pipes – water meter wells – main pipes – branch pipes – equipment used for water consumption; this approach helps to save time and ensure accuracy. The same principle applies to electrical systems: distribution boxes – wire circuits – electrical equipment, etc. In other words, it’s about starting from the source, moving through the connections, and ending at the equipment. By following this method, you won’t get confused and will be able to identify the key points, thus understanding each drawing.