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Electrical installation methods, procedures and requirements
Published in Trevor Linsley, Electrical Installation Work Level 2, 2019
Trunking, conduits, cables and tray must be installed securely, but most of all they must be installed horizontally or vertically for a professional finish. A long spirit level is very useful in determining what is horizontal and vertical, although a plumb line can also be used to determine the vertical. A plumb line is a piece of string with a steel weight attached to the bottom. Holding the string up against a wall, the steel weight at the bottom will initially swing like a pendulum, but quickly come to rest in a true vertical line. If a little chalk is first rubbed onto the line, it becomes a chalk line. If an assistant holds the steel weight in its rest position so that the line presses against the wall, and then plucks the string so that it bounces against the wall, the chalk will transfer to the wall, leaving a true vertical line on the wall. When the measuring and marking out is completed, the electrician can begin the process of installing the trunking, conduits, cables or tray.
C&G Unit 204: Installation of wiring systems and enclosures
Published in Trevor Linsley, Basic Electrical Installation Work, 2018
Trunking, conduits, cables and tray must be installed securely, but most of all they must be installed horizontally or vertically for a professional finish. A long spirit-level is very useful in determining what is horizontal and vertical, although a plumb-line can also be used to determine the vertical. A plumb-line is a piece of string with a steel weight attached to the bottom. Holding the string up against a wall, the steel weight at the bottom will initially swing like a pendulum, but quickly come to rest in a true vertical line. If a little chalk is first rubbed onto the line, it becomes a chalk line. If an assistant holds the steel weight in its rest position so that the line presses against the wall, and then plucks the string so that it bounces against the wall, the chalk will transfer to the wall, leaving a true vertical line on the wall.
Survey and Setting Out
Published in S. Ponnuswamy, D. Johnson Victor, Transportation Tunnels, 2017
S. Ponnuswamy, D. Johnson Victor
The plumb lines are of fine piano wire and each carries a symmetrical lead weight of about 300 N (the wire being strained to half its breaking strength). In deep shafts particularly the bobs used may have projecting vanes contained in a canister with a hood to reduce rotation and oscillation of the wires. It is also customary to fill the canister with water or oil. In very deep shafts bobs weighing up to 1.3 kN are used to reduce oscillations but thicker wires are required and also geared winches to control lowering/lifting. The two wires are suspended as far apart as possible. It is very difficult to do setting out the alignment below precisely using this method, due to difficulty in preventing oscillation in the plumb/ reference wires.
Development of historic building information modelling: a systematic literature review
Published in Building Research & Information, 2022
Sumeyye Sena Bastem, Asli Cekmis
Traditionally, data are collected using manual measuring devices (e.g. metres, plumb line, and topographic measurement instruments) from existing and heritage structures. With the development of technology, photogrammetry and terrestrial laser scanning (TLS) are being utilized for data collection; these tools accelerate data collection and decrease errors and deficiencies relative to the traditional method. Despite the development of methodology and improvement in the relevant tools, CAD software has been used in transferring data to computers since the 1970s. 2D projects are generally created in a CAD environment and frequently revised during the survey and restoration process. In addition to the designing stages, difficulties such as those encountered in archiving documents, management and implementation of decisions encourage the use of BIM in heritage structures (Ali et al., 2018; Antonopoulou & Bryan, 2017; John & Tim, 2017; Maietti et al., 2017; Yen & Lu, 2019). Surveyors, engineers, architects, project consultants, conservation planners, fire-health-safety specialists and owners are actively involved in the creation and pre-decision process of the HBIM model. Historians and archaeologists also support this technical process by collecting and integrating semantic information. In the repair and restoration phases, technicians, suppliers, manufacturers and contractors take an active role. Users such as owners, CEO, governments part are regarded and important stakeholders through the process of the HBIM due to the participatory design and sustainable conservation strategies.
Enhancing dam safety evaluation using dam digital twins
Published in Structure and Infrastructure Engineering, 2023
Xi Zhu, Tengfei Bao, Justin K. W. Yeoh, Ningxiao Jia, Hui Li
On the other hand, external-mounted monitoring instruments are usually installed on the surface of hydraulic structures, observation galleries, or bank slope to measure structural deformation, seepage, and environmental variables. This type of monitoring instruments, such as tensile-wire instruments, hydrostatic level instruments, and plumb-line instruments, are usually combinations of measuring sensors and some auxiliary facilities. Taking the method of tension wire alignment as an example, it is the most important and common method currently used to measure horizontal displacements of dams, and it is implemented by measuring the distances between measuring points and the datum line.