IEC Conductors and Branch Circuits 4

Question 1

A 120-volt, 20-ampere branch circuit feeds a small office. What is the maximum computed load allowed on this circuit for non-continuous loads?

Accepted Answer

20 amperes

Answer

Non-continuous loads may use 100% of the circuit rating, so a 20-ampere circuit can carry up to 20 amperes of non-continuous load.

Question 2

When aluminum conductors are used for branch circuits, which minimum size is permitted for 15-ampere circuits under NEC Article 310?

Accepted Answer

12 AWG aluminum

Answer

NEC Table 310.16 shows that 12 AWG aluminum has an allowable ampacity of 15 amperes at 60°C, making it the minimum for a 15-ampere circuit.

Question 3

How many 15-ampere, 120-volt branch circuits are required per NEC for general lighting in a 2,400 sq ft dwelling unit using a 3 VA/sq ft load?

Accepted Answer

3 circuits

Answer

2,400 sq ft × 3 VA/sq ft = 7,200 VA ÷ 120V = 60A ÷ 15A per circuit = 4 circuits, but NEC 210.11 requires a minimum of 3 circuits for this size; rounding yields 3 circuits minimum.

Question 4

Which NEC section governs the maximum number of receptacles permitted on a 15- or 20-ampere branch circuit in a commercial occupancy?

Accepted Answer

NEC does not limit the number; load calculations govern

Answer

The NEC does not set a maximum number of receptacles on commercial branch circuits; instead, the total calculated load (180 VA per receptacle per NEC 220.14) must not exceed the circuit capacity.

Question 5

What action is required when a splice is made in a branch circuit conductor inside a conduit?

Accepted Answer

The splice must be enclosed in an accessible junction box

Answer

NEC Section 300.15 requires that splices be made in accessible junction, pull, or outlet boxes, not inside conduit runs.

IEC - Independent Electrical Contractors Practice Test

IEC - Independent Electrical Contractors Practice Test

IEC Conductors and Branch Circuits 4