General Contractor License Mechanical, Electrical, and Plumbing Systems 3

Question 1

Under the NEC, what is the maximum circuit breaker size permitted for a 20-ampere-rated, 120V household receptacle circuit using 12 AWG copper wire?

Accepted Answer

20 amperes

Answer

12 AWG copper wire has an ampacity that permits a maximum 20-ampere overcurrent device for a standard 120V branch circuit under the NEC.

Question 2

A contractor discovers the water supply pressure at a residential project measures 95 psi. What corrective action is required by code?

Accepted Answer

Install a pressure reducing valve (PRV) to bring pressure below 80 psi

Answer

The IRC requires a pressure reducing valve when water supply pressure exceeds 80 psi to protect plumbing fixtures and appliances from damage.

Question 3

What type of pipe expansion joint is required when installing long runs of copper water supply pipe to accommodate thermal expansion?

Accepted Answer

Expansion loop or offset

Answer

Long copper pipe runs require expansion loops or offsets to absorb thermal expansion and prevent stress cracking at joints and fittings.

Question 4

According to NFPA 70 (NEC), arc-fault circuit interrupter (AFCI) protection is required in which residential area?

Accepted Answer

All 120V, 15A and 20A branch circuits in dwelling unit bedrooms and most living areas

Answer

NEC requires AFCI protection on all 120V, 15A and 20A branch circuits serving bedrooms and most other living areas in dwelling units to prevent arc-fault fires.

Question 5

What is the primary purpose of a condensate neutralizer installed on a high-efficiency (condensing) gas furnace?

Accepted Answer

Raise the pH of acidic condensate before it enters the sanitary drain

Answer

High-efficiency condensing furnaces produce acidic condensate (pH 2–4) that can corrode pipes and violate codes; a neutralizer raises pH to an acceptable level before discharge.

General Contractor License Practice Test

General Contractor License Practice Test

General Contractor License Mechanical, Electrical, and Plumbing Systems 3