Article 240 Overcurrent Protection

Question 1

A conductor other than a service conductor, that has overcurrent protection ahead of it’s point of supply that exceeds the value permitted for similar conductors.

Answer 1

Tap Conductor

Article 240.2

Question 2

Unless specifically permitted, the overcurrent protection shall not exceed that required below for small conductors.

(1) 18 AWG
(2) 16 AWG
(3) 14 AWG
(4) 12 AWG
(5) 10 AWG

Answer 2

(1) 7A
(2) 10A
(3) 15A
(4) 20A
(5) 30A

Article 240.4 (D)

Question 3

Which transformers secondary connections are permitted to be protected by an overcurrent device on the primary side?

Answer 3

Single-phase having 2-wire (single voltage) and three-phase delta-delta having a 3-wire (single voltage)

Article 250.4 (F)

Question 4

True or False

The use of fuses and inverse time circuit breakers with nonstandard ampere ratings shall not be permitted.

Answer 4

False

Article 240.6

Question 5

What table has standard ampere ratings for fuses and inverse time circuit breakers.

Answer 5

Table 240.6 (A)

Table 240.6 (A)

Question 6

Where an orderly shutdown is required to minimize the hazards to personnel and equipment, a system of ____ shall be permitted.

Answer 6

COORDINATION

Article 240.12

Question 7

No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met:

Answer 7

The overcurrent device opens all conductors, including the grounded conductor, and is designed so no pole can operate independently.

Where required for motor overload protection.

Article 240.22

Question 8

Switches containing fuses and circuit breakers shall be readily accessible and installed so the center of the grip of the operating handle, when in its highest position, is not more than _____ above the floor.

Answer 8

6’ 7”

Article 240.24

Question 9

Plug fuses shall be permitted to be used in the following circuits:

Answer 9

(1) Circuits not exceeding 125 volts between co doctors
(2) Circuits supplied by a systemhaving a grounded neutral point where thr line-to-neutral voltage does not exceed 150 volts

Article 240.50 (A)

Question 10

Plug fuses of 15A and lower rating shall be identified by a _____.

Answer 10

hexagonal configuration of the window, cap, or other prominent part to distinguish them from fuses of higher ratings.

Article 240.50 (C)

Question 11

The screw shell of a plug type fuse holder is connected to which side of the circuit?

Answer 11

The load side

Article 240.50 (E)

Question 12

Where fuses rated 1200A or higher are installed, they are required to have a clearing time of ____

Answer 12

0.07 seconds or less.

Article 240.67 (B)

Question 13

Where circuit breaker handles are operated vertically rather than rotationally or horizontally, what position of the handle should indicate “on”?

Answer 13

The “up” position is the “on” position.

Article 240.81

Question 14

Circuit breakers used as switches in 120V and 277V flourescent lighting circuits shall be listed and marked ____. Circuit breakers used as switches in high-intensity discharge lighting circuits shall be listed and marked ____

Answer 14

SWD or HID HID

Article 240.83 (D)