Deck 24: Gas and Oil Central Heating Systems

Question 1

Class 2 circuits are ____________________ and are considered safe from fire hazard and from electric shock hazard

Answer 1

"power-limited"
"power limited"
power limited
power-limited

Question 2

In the diagram below, label the type of circuit represented by each part of the installation, choosing from among the following. You may or may not require all the types listed. Power supply wiring
Class 1 wiring
Class 2 wiring
Class 3 wiring
Communications wiring

Answer 2

A = Class 2 wiring
B = Power supply wiring
C = Class 1 wiring

Question 3

How does the Code define a remote-control circuit?

Answer 3

A remote-control circuit is any circuit that controls another circuit through a relay or equivalent device.

Question 4

Residential thermostats should be located where they will not be influenced by ____.

A) drafts or currents from air registers
B) radiated heat from appliances, lamps, etc.
C) direct rays of the sun
D) all of the above

Question 5

Do not throw selenium thermostats into the trash because the selenium is considered hazardous waste material.

Question 6

Disconnect switches for furnaces installed in basements are required to be ____.

A) suitable for damp locations
B) installed within sight of the appliance
C) fused
D) all of the above

Question 7

Which of the following is NOT a typical Class 2 wiring application in homes?

A) thermostats
B) security systems
C) doorbell chimes
D) low-voltage lighting

Question 8

Explain the purpose of interrupted duty ignition on a gas furnace.

Question 9

Low-voltage wiring used for door bell and thermostat wiring in a residence is generally Class 2 wiring, which has a thermoplastic insulation with a voltage rating of not less than ____________________ volts.

Question 10

NEC 422.12 requires that central heating equipment of any type (electric resistance, gas, oil, heat pump) must ____.

A) have a disconnect mounted within sight of the unit
B) be supplied by an individual branch circuit
C) have a supplemental power source
D) both b and c

Question 11

Because they have internal overload protection, listed Class 2 transformers are permitted to be supplied by branch circuits having overcurrent protection not exceeding ____ amperes.

A) 15
B) 20
C) 30
D) 50

Question 12

Thermostats are usually mounted approximately ____ in. above the finished floor.

A) 36
B) 52
C) 60
D) 76

Question 13

Most residential heating systems are packaged units in which many items are preassembled, prewired parts of the furnace or boiler. They are included in an integrated printed circuit board module, which is the "____" of the system.

A) core
B) brain
C) guts
D) heart

Question 14

Class 2 wiring ____ permitted in the same raceway, cable, compartment, outlet box, or fitting with light and power conductors, even if the Class 2 conductors have the same 600-volt insulation as the power conductors.

A) is
B) is not

Question 15

Oil-fired heating systems move hot air from the furnace through hot air ducts that in turn connect to hot air registers strategically located throughout the home.

Question 16

____ circuits offer alternative wiring methods regarding voltage, power limitations, wire size, derating factors, overcurrent protection, physical protection, insulation, and materials that differentiate these types of circuits from conventional wiring methods.

A) Class 1
B) Class 2
C) Class 3
D) all of the above

Question 17

Hot water systems are very adaptable to zone control by using a combination of one or more circulating pumps and/or valves for the different zones. Hot water heating systems are referred to as ____________________ systems.

Question 18

A remote-control circuit is any electrical circuit that ____________________ through a relay or equivalent device.

Question 19

Class 2 power source voltage limitations, current limitations, and overcurrent protection requirements are found in ____.

A) Article 220
B) Article 240
C) Article 725
D) Chapter 9, Tables 11(a) and 11(b)

Question 20

Manufacturers of heating and cooling equipment provide separate openings for bringing in the Class 2 wiring and separate openings for bringing in the power supply.