Basic Electrical Installation Work

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They are good insulators, but give off toxic fumes when burned. An insulator material, usually non-metal, which the electrons are very firmly bound the nucleus and, therefore, will not allow heat elec- tricity pass through it. What makes them differ- ent materials the way which the atoms and electrons are arranged and how strongly the electrons are attracted the atoms. Definition Corrosion The destruction metal by chemical action. Definition An insulator material, usually a non metal, which the electrons are very firmly bound the nucleus and, therefore, will not allow heat elec- tricity pass through it.Basic Electrical Installation Work 100 Properties conductors and insulators In Fig. All materials are made atoms and electrons. They have a flexible quality when operated maximum temperature 70°C but should not flexed when the air temperature near 0°C, otherwise they may crack. Non-ferrous Metals which not contain iron are called non-ferrous. These electrons can easily become ‘free electrons’ which allows heat and electricity pass easily through the material. Thermosetting polymers Once heated and formed, products made from thermosetting polymers are fixed rigidly. Definition Thermoplastic polymers These may be repeatedly warmed and cooled with- out appreciable changes occurring in the properties the material.1 the last chapter looked the atomic structure materials. Copper, aluminium, tin, lead, zinc and brass are examples non-ferrous metals. Synthetic artificial rubber carefully manufactured have all the . Let now define the terms and properties some the materials used in the electrotechnical industry. Ferrous metals have magnetic properties. Plug tops, socket outlets and switch plates are made from this material. Definition Polyvinylchloride (PVC) used for cable insulation thermoplastic polymer. Definition Alloy alloy mixture two or more metals. These electrons can easily become ‘free electrons’ which allows heat and electricity pass easily through the material. Alloy alloy mixture two more metals. Definition Non-ferrous Metals which not con- tain iron are called non-ferrous. Rubber tough elastic substance made from the sap tropical plants. It good insulator, but degrades and becomes brittle when exposed to sunlight. Most corrosion takes place when metal contact with moisture (see also mild steel and zinc). 4. Ferrous word used describe all metals which the main constituent is iron. Synthetic rubber manufactured, opposed being produced natu- rally. A conductor material, usually metal, which the electrons are loosely bound the central nucleus. Corrosion The destruction metal chemical action. Brass alloy cop- per and zinc, usually the ratio 70–30% 60–40%. Cast iron, wrought iron and steel are all ferrous metals. They are non-magnetic and resist rusting. Definition A conductor material, usually a metal, which the electrons are loosely bound the central nucleus. Definition Ferrous word used describe all metals which the main constituent is iron. Thermoplastic polymers These may repeatedly warmed and cooled without appreciable changes occurring the properties the material. Polyvinylchloride (PVC) used for cable insulation thermo- plastic polymer. The word ‘ferrous’ comes from the Latin word ferrum meaning iron