Color codes
Different color wires serve different purposes, like:
· Black: Hot wire, for switches or outlets.
· Red: Hot wire, for switch legs and for connecting wire between two hardwired smoke detectors.
· Blue and Yellow: Hot wires, pulled in conduit. Blue for 3-4 way switch application, and yellow for switch legs to control fan, lights etc.
· White: Always neutral.
· Green and Bare Copper: Only for grounding.
Exercise 1. Answer the questions
1. What is the difference between wire and cable?
2. What is the wire gauge?
3. What does wire lettering represent?
4. What wire type is used in service drop conductors?
5. Why are non-metallic sheath wires preferred for in-house wiring?
6. What insulation is used in non-metallic sheath wires?
7. What color is the ground wire?
Exercise 2. Match the words with their definitions
1. wire a) a wire which comes from the bottom terminal of the switch and becomes hot when the switch is turned on; it is used to turn the load on and off
2. cable b) a flexible insulated electric cable, used especially to connect appliances to mains
3. cord c) an overhead electrical line running from a utility
pole, to a customer’s building or other premises
4. service drop d) a flexible metallic conductor, usually insulated, used to carry electric current in a circuit
5. weatherhead e) a grouping of two or more independent electrical wires
6. switch leg f) a weatherproof receptacle at the service drop entry point where overhead conductors enter a building
Unit 3. Watt hour meters
Vocabulary
accuracy точность
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automatic meter reading system система автоматизированного
снятия показаний счетчика
counter mechanism счетный механизм
current coil обмотка тока
dial циферблат; круговая шкала
eddy current вихревой ток
electromagnet электромагнит
electromechanical induction meter электромеханический индукци-
онный счетчик
to exert force прилагать силу
flux поток
gear train зубчатая передача
high end processor высокопроизводительный про- цессор
instantaneous voltage мгновенное напряжение
to lag отставать
meter счетчик
metering point место измерения
phase angle угол сдвига фаз, фазовый угол
power line communication ВЧ-связь по ЛЭП
pressure coil обмотка напряжения
product произведение, результат умноже- ния
pulse rate частота повторения импульсов
smart energy meter интеллектуальный счетчик элек- троэнергии
spindle ось, вал
utilities коммунальные предприятия