Chapter 11 Electrical Utilities

Question 1

What is the definition of high voltage?

Answer 1

Anything over 600 volts

Question 2

What are the four types of lines used to conduct electricity?

Answer 2

Transmission, subtransmission, primary distribution, and secondary distribution

Question 3

What is the pprimary function of a transformer?

Answer 3

Transformers are used either to reduce or increase voltages as necessary.

Question 4

What is the best method to determine the approximate voltage of conductors?

Answer 4

The size of the insulators and the distances between them

Question 5

What are the three primary ways to eliminate the electrical service to a structure?

Answer 5

Depend on local Utility companies, shut off the service, and cut the drip loops

Question 6

Why shouldn’t you pull a meter to eliminate the electrical service?

Answer 6

A meter can flash or explode, live line connectors will be exposed, and the meter may have been bypassed

Question 7

What are the three types of main power disconnects?

Answer 7

Fused pullout, circuit breaker, and lever

Question 8

Should suppression personnel enter electrical rooms marked “high voltage” to curtail the flow of electricity?

Answer 8

No. ONly appropriate utility company personnel should enter these areas to curtail the flow of electricity

Question 9

What is the only practical way to ascertain the distribution of electrical power within complex occupancies?

Answer 9

Preplanning with qualified building engineers

Question 10

What is a UPS room, and what are its specific hazards?

Answer 10

Uninterrupted power supply rooms. The hazards are potential acid spills, vapors from charging batteries, and bare bus bars

Question 11

Electricity can be transmitted to municipalities on lines of how many volts?

Answer 11

115,000 volts to 1 million volts

Question 12

Subtransmission lines carry what voltage?

Answer 12

34,500 volts

Question 13

Primary distribution lines carry what voltage?

Answer 13

4,800 volts

Question 14

Secondary distribution lines carry what voltage?

Answer 14

480 volts, 240 volts, 120 volts

Question 15

Why can 4,800 volts be more dangerous than 34,500 volts?

Answer 15

An apparently dead wire can suddently become live when relays automatically set

Question 16

Where can transformers be located? (3)

Answer 16

Above ground on poles
On the ground on concrete pads
Underground in vaults

Question 17

What is considered high voltage and requires marking with “high-voltage” signs

Answer 17

750 volts and above

Question 18

Subtransmission line (34,500 volts) insulators are how long?

Answer 18

12-22 inches

Question 19

Primary distribution line (4,800 volts) insulators are how long?

Answer 19

4-6 inches

Question 20

Secondary distribution line (480, 240, 120 volts) are how long?

Answer 20

2-3 inches

Question 21

Transmission line (115,000 to 1,000,000 volts) insulators can be how long?

Answer 21

4 feet to 14 feet long

Question 22

Where are Subtransmission transformers usually located?

Answer 22

Normally mounted on a platform between poles

Question 23

What is the safest and most effective method to prevent injury from electric shock?

Answer 23

eliminate all electrical service to a structure

Question 24

If it is necesary, how should a meter be removed?

Answer 24

Do not pull outward. pull upward towards the source of supply, then out

Question 25

What is the minimum tools and equipment required when cutting electrical conductors?

Answer 25

Turnouts
Eye protection
Gloves–Rubber or leather
Axe, Wire cutters, hot stick

Question 26

When cutting drip loops, do not cut wires that carry what voltage?

How much wire do you leave?

Answer 26

over 750 volts

At least 6 inches

Question 27

Describe a single-phase triplex service line.

Answer 27

two covered conductors and one bare conductor

Question 28

Describe a three-phase triplex service line.

Answer 28

Three covered conductors and one bare conductor

Question 29

Who’s responsible for any electrical hazard?

Answer 29

The first person that sees it

Question 30

What should you always check for after eliminating electrical service to a structure?

Answer 30

Any additional electrical services that may have been overlooked

Question 31

Pad mount transformers can be classified into two classifications? What are they and what are their voltages?

Answer 31

Commercial stations (CS) 4,800 volts

Industrial stations (IS) 34,500 volts

Question 32

What can you check power poles for to determin approx voltage?

Answer 32

High voltage signs
insulator size
Transformer markings

Question 33

After cutting wires, what should you do to the cut wires to prevent other personnel from thinking that the wires are charged?

Answer 33

coil the wires

Question 34

What is step potential?

Answer 34

stepping near or between energized wires on the ground can be electrocuted by this phenomenon

Question 35

Pole-mounted transformers usually provide what?

Answer 35

voltage drop from 34,500 volts to 4,800 volts or

4,800 volts to 480/240/120 volts

Question 36

What voltages can be encountered in street electrical vaults?

Answer 36

4,800 volts to 34,500 volts

Question 37

What shape are the manhole covers that will usually indicate a vault?

Answer 37

square

Question 38

Newer street lights with photoelectric cells are fed by how much voltage?

Answer 38

240 volts

Question 39

Older street lights without photoelectric cells are fed by how many volts?

Answer 39

6,800 volts

Question 40

What voltage do traffic lights operate on?

Answer 40

240 volts

Question 41

Telephone line voltages can range from what?

Answer 41

45 volts to over 100 volts

Question 42

What component of electricity is responsible for injury and death?

Answer 42

amperage