H1 LT1

Question 1

What type of voltage do most appliances in residential construction use?

Answer 1

Single-phase voltage

Question 2

Who owns the meter and meter socket?

Answer 2

Meter - supply authority, Meter socket - consumer

Question 3

What is the name of the busses that are not connected to the ground?

Answer 3

Ungrounded busses

Question 4

Where can service conductors connect to?

Answer 4

Line side of a main fusible switch

Question 5

Why must the neutral wire not be fused?

Answer 5

For safety reasons, to prevent unequal division of voltage across loads if it were to open in an unbalanced three-wire system.

Question 6

What is the voltage fixed at on the secondary winding of a single-phase system?

Answer 6

240 volts

Question 7

What is the name of the bonding wire that connects the neutral bus to the grounding bus?

Answer 7

Bond strap

Question 8

What is on the load side of the switch?

Answer 8

Fuses and load terminals

Question 9

What is the purpose of fusing the line wires but not the neutral wire?

Answer 9

Safety, to avoid creating an unbalanced condition that could harm loads.

Question 10

What is the color of the neutral wire in the secondary winding?

Answer 10

White or natural grey

Question 11

What is the name of the section of the panelboard that contains the main circuit breaker?

Answer 11

Service box section

Question 12

What does a load centre contain?

Answer 12

Circuit breakers for branch circuits

Question 13

What hazard could be created if a fuse in the neutral were to open?

Answer 13

Shock hazard

Question 14

What are the two outer wires in a three-wire circuit called?

Answer 14

Line wires or hot wires

Question 15

What voltage level could result in a shock if a person were in contact with a grounded surface?

Answer 15

120 V

Question 16

What is the purpose of a kilowatt-hour meter in a residential dwelling?

Answer 16

To record amount of electrical energy used

Question 17

Why is the neutral grounded at the transformer and main power?

Answer 17

To limit shock hazard to 120 V

Question 18

What unit is electrical energy measured in by a kilowatt-hour meter?

Answer 18

kWh

Question 19

What is a combination panelboard?

Answer 19

Main circuit breaker located in the same enclosure as branch-circuit breakers

Question 20

What happens if the neutral wire in an unbalanced three-wire system opens?

Answer 20

It creates an unequal division of voltage across the loads, possibly damaging them.

Question 21

How is the 240 volts divided in a three-wire system?

Answer 21

To provide 120-volt and 240-volt supplies

Question 22

What happens to the fuse when a high fault current flows in a circuit?

Answer 22

Blows to protect circuit

Question 23

Where is the neutral wire grounded in a single-phase, three-wire system?

Answer 23

Transformer and residential service box

Question 24

What are the three ways to control the power supply after it is fed through the kilowatt-hour meter?

Answer 24

A combination panelboard, a main circuit breaker, a main switch incorporating fuses

Question 25

What are the major advantages of a single-phase, three-wire system?

Answer 25

Two voltages available, Improved safety, Reduced copper requirement