Basic Electrical Installation Work

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Strana 389 z 399

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Instructed person instructed person person adequately advised supervised skilled persons able avoid the dangers which electricity may create. Hazard hazard something with the ‘potential’ cause harm, for example, chemicals, electricity working above ground. Inspection and testing techniques The testing installation implies the use instruments obtain readings. Force The presence force can only detected its effect body. Fuse fuse the weakest link the circuit. Hazard risk assessment Employers more than five people must document the risks work and the process known hazard risk assessment. Fluorescent lamp fluorescent lamp linear arc tube, internally coated with fluorescent powder, containing low-pressure mercury vapour discharge. Gravitational force Gravitational force the force acting towards the centre the earth due to the effect gravity. force may cause stationary object move bring moving body rest. causes the current the circuit lag behind the applied voltage. Heating, magnetic chemical The three effects electric current: When electric current flows a circuit can have one more the following three effects: heating, mag- netic chemical.c. Insulator insulator material, usually non-metal, which the electrons are very firmly bound the nucleus and, therefore, will not allow heat or . Under fault conditions will melt when overcurrent flows, protecting the circuit conductors from damage. Friction force Friction force the force which resists prevents the movement two surfaces contact. Impedance The total opposition current flow a.c. Inertial force Inertial force the force required get things moving, change direction or stop. Hazardous area area which explosive gas–air mixture present called hazard- ous area, and any electrical apparatus equipment within hazardous area must classified flameproof protect the safety workers’. However, test unlikely identify cracked socket outlet, a chipped loose switch plate, missing conduit-box lid saddle, is also necessary make visual inspection the installation. current inductive circuit. Inductive reactance Inductive reactance (XL) the opposition a. All existing installations should periodically inspected and tested ensure that they are safe and meet the regulations the IEE (Regulations 610 634). circuit called impedance and given the symbol Z. Functional switching Functional switching involves the switching off, varying the sup- ply, electrically operated equipment normal service.Glossary terms 378 Flexible conduit Flexible conduit manufactured 731-1: 1993 made interlinked metal spirals often covered with PVC sleeving