TN LLE Overcurrent Protection 2

Question 1

Per NEC 240.4(B), when can the next standard size overcurrent device be used above the conductor ampacity?

Accepted Answer

When the ampacity does not correspond to a standard device rating AND the circuit does not supply multioutlet receptacle branch circuits

Answer

NEC 240.4(B) permits the next higher standard overcurrent device rating when the conductor ampacity doesn't match a standard size, provided the circuit isn't a multioutlet receptacle branch circuit.

Question 2

What are the standard ampere ratings for fuses and circuit breakers per NEC 240.6(A)?

Accepted Answer

15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200 (and continuing)

Answer

NEC 240.6(A) lists the standard ampere ratings starting at 15 and including specific values up through 6,000 amperes.

Question 3

Per NEC 240.21(B), what is the maximum length for a feeder tap conductor that is at least 1/3 the ampacity of the feeder OCPD?

Accepted Answer

25 feet

Answer

NEC 240.21(B)(2) permits tap conductors up to 25 feet in length if they have ampacity not less than 1/3 of the feeder OCPD rating and terminate in a single OCPD.

Question 4

What is the difference between an inverse-time circuit breaker and an instantaneous-trip circuit breaker?

Accepted Answer

Inverse-time provides both overload and short-circuit protection; instantaneous-trip provides only short-circuit protection

Answer

Inverse-time breakers have a time-delay element for overload protection plus instantaneous trip for short circuits. Instantaneous-trip breakers respond only to short-circuit level faults.

Question 5

Per NEC 240.24(A), what accessibility requirement applies to overcurrent devices?

Accepted Answer

They must be readily accessible

Answer

NEC 240.24(A) requires overcurrent devices to be readily accessible — meaning they can be reached without climbing, removing obstacles, or using portable tools.

TN LLE - Tennessee Limited Licensed Electrician Practice Test

TN LLE - Tennessee Limited Licensed Electrician Practice Test

TN LLE Overcurrent Protection 2