132

NEC® Section ___ covers standard size fuses and breakers.

240.6

What size breaker is shown in Panel A for the air conditioner? (EWR Print)

45-amp, double-pole

The nameplate rating of the EWR electric dryer is ___ watts.

5,700

What size breaker is shown in Panel A for the electric furnace? (EWR Print)

70-amp, double-pole

Generally, an overcurrent protective device is not permitted to be continuously loaded to more than ___ percent of its rating.

80

Which of the following circuit conditions will cause a circuit breaker to trip? I. short-circuit II. overload III. normal

I & II only

A 240-volt load, such as a window unit air conditioner, would require breaker ___ to be installed in the panelboard.

answer a

To provide accurate protection for prolonged overloads, a dual-element, time-delay fuse will open after about 10 seconds at a current of ___ times the fuse rating.

five

The NEC® has limitations on where OCPDs, such as panelboard installations, can be installed due to the presence of combustible materials. These are specified at ___.

none of these

Usually, load centers are not available with "bolt-on" circuit breakers.

true

Which of the following are standard size circuit breakers? I. 55 II. 60

II only

Which of the following types of current travel through a fuse?

all of these

Generally, the NEC® permits a fuse to carry ___ percent of its rating when it supplies a load that is not operated continuously.

100

The main OCPD (OverCurrent Protection Device) shown for EWR Panel A is a ___ fuse.

125-amp

What size spare breakers are located in Panel B? (EWR Print)

15-amp, single-pole

Article ___ of the NEC® covers the requirements for fuses, fuseholders, and fuse adapters.

240, Part V

Scenario 132.31 Circuit #1 has all conduit fittings tight and the equipment grounding conductor is bonded to each metal box. Circuit #2 has loose conduit fittings and the equipment grounding conductor was not bonded to each metal box. Refer to Scenario 132.31. In the event of a ground fault, the circuit breaker for ___ will open more quickly than the other circuit.

Circuit #1

Which of the following are standard size circuit breakers? I. 700 II. 750 III. 800

I & III only

A 15-amp circuit breaker opens very quickly (within 1 second) when subjected to ___. I. a ground fault of 250 amps II. a short circuit of 450 amps III. an overload of 16 amps

I or II only

A dual-element, time-delay fuse opens very quickly when subjected to a(n) ___. I. ground fault II. short circuit III. overload

I or II only

Which of the following are standard size circuit breakers? I. 20 II. 25 III. 30

I, II & III

When a load calculation results in an ampere rating that does not match the ampacity of the conductor, which of the following is permitted?

Select an OCPD of the next higher standard ampere rating.

When plug fuses are used on all new installations such as in a disconnect switch for a clothes dryer, the fuses must be ___.

Type S

Generally, circuit breakers ___ permitted to be connected to a neutral conductor.

are not

Generally, overcurrent devices ___ permitted to be connected to the grounded circuit conductor.

are not

Panel B is mounted on the ___ wall in the house. (EWR Print)

west

What is the maximum voltage between circuit conductors when using plug fuses?

125

Plug fuses can be used on which of the following voltage systems? I. 120/240-volt, 1-ph, 3-wire II. 120/208-volt, 3Ø, 4-wire III. 277/480-volt, 3Ø, 4-wire

I & II only

___ is a type of circuit condition. I. ground fault II. open circuit III. normal

I, II & III

A breaker panel is permitted to be located ___. I. in the bathroom in a house II. in an electrical room in a school III. in a bathroom in a restaurant

II & III only

Figure 132.111 The conductors at Point ___ in Figure 132.111 are service-entrance conductors. The service point is at the weatherhead. I. A II. B III. C

II & III only

A fused switch is permitted to be located ___. I. in the bathroom in a house II. in an electrical room in a school III. in a bathroom in a hotel room

II only

Which of the following is a type of circuit condition? I. selective coordination II. overload

II only

When a ground fault occurs, the OCPD will trip very quickly if the fault current has an effective ground-fault current path (a low-resistance return path) to take by way of the equipment grounding conductor. The lower this resistance, the faster the OCPD opens. Which of these ground-fault current return paths has the least (or lowest) resistance where run between two metal boxes? The copper equipment grounding conductor is bonded (or connected) to each box.

a 3/4" EMT with a 12 AWG copper equipment grounding conductor

Which of the following are standard size circuit breakers? I. 125 II. 150

both I & II

Usually, panelboards are constructed to have a depth that is ___ than that of a load center.

deeper

When a tripped breaker is found, you should ___.

determine the cause of the trip and correct it before resetting the breaker

If a circuit breaker trips, you should ___.

determine why it tripped before resetting the breaker

According to Ohm's Law, when all conduit fittings are tight and the equipment grounding conductors are bonded to each metal box, the total resistance of the ground-return path ___. Consequently, when a ground fault occurs, the overcurrent protective device (fuse or breaker) can open as quickly as possible because the fault current is as high as possible. HINT: I = E ÷ R

is decreased

Figure 132.101 The panel shown in Figure 132.101 is 120/208-volt, 3Ø, 4-wire. The disconnect switch is fused with plug fuses and supplied from a 2-pole breaker in space 6-8 in the panel. This ___ a Code violation.

is not

Does the NEC® permit a panelboard to be installed in a clothes closet in a school?

no

Between a 2-pole, 20-Amp circuit breaker and a load, 10 AWG, 2-wire AC cable is installed. If the load is drawing 19 amps, this is a(n) ___ condition.

normal

Generally, circuit breakers must be ___.

readily accessible

A circuit is installed in EMT between a 2-pole circuit breaker and a load. If the "hots" are touched together in a junction box somewhere in the pipe run, this is a(n) ___ condition.

short-circuit

In general, overcurrent protection of conductors is ___.

sized according to the ampacity of the conductor

Figure 132.101 Refer to Figure 132.101. The disconnect switch is fused with plug fuses and supplied from a 2-pole breaker in space 8-10 in the 277/480-volt, 3Ø, 4-wire panel. This is a Code violation.

true