Mains Electricity

Question 1

what colour is the live wire?

Answer 1

brown

Question 2

what colour is the neutral wire?

Answer 2

blue

Question 3

what colour is the earth wire?

Answer 3

green

Question 4

why is the live wire the shortest?

Answer 4

if cable is tugged it pulls out first

Question 5

what is thr purpose of the neutral wire?

Answer 5

provides a way for the current to return

p.d. is zero in a neutral wire

Question 6

what is the purpose of the earth wire?

Answer 6

safety - provides low resistance path for current in case of fault so fault current is large and blows fuse

Question 7

what material is the outer casing made of?

Answer 7

plastic - insulator (no shock)

Question 8

voltage in live pin

Answer 8

alternating current 330V to -330V

Question 9

voltage in neutral pin

Answer 9

p.d. stays close to zero

Question 10

what is the peak voltage in the u.k.?

Answer 10

330V

Question 11

what is the average voltage?

Answer 11

230V

Question 12

frequency used in generators

Answer 12

50Hz

Question 13

how are fuses designed?

Answer 13

designed to melt when a given current passes through it due to overheating
-this breaks circuit so current stops

Question 14

how are circuit breakers designed?

Answer 14

(operated magnetically)
breaks live connection when current is too high
- can be reset

Question 15

what is a RCCB?

Answer 15

residual current circuit breakers

Question 16

how is RCCB designed?

Answer 16

to break connection at low current level

Question 17

what is RCCB designed for?

Answer 17

devices in hazardous conditions where dander of electirc shock is greater (e.g. lawn mower)

Question 18

what are double insulators?

Answer 18

appliances have wire insulating and outer casing insulating so no chance of electric shock (e.g. electric kettle)

Question 19

how much does an electrical company typically charge for electricity?

Answer 19

12p per kWh