ALASKA (AK) Mechanical Administrator Unlimited Commercial and Industrial
Plumbing Exam LATEST QUESTIONS AND CORRECT ANSWERS GRADE A
What is the minimum required size for the drain outlet for a commercial garbage disposal
unit with a 1-1/2 horsepower motor, according to the Uniform Plumbing Code (UPC)?
A) 1-1/2 inches
B) 2 inches
C) 3 inches
D) 4 inches
**Answer: B**
**Explanation:** UPC 802.2.1 requires a drain outlet of not less than 2 inches for
commercial food waste grinders with motors of 1 horsepower or greater.
When sizing the water heater for a commercial laundry facility, what is the primary factor
that must be determined first?
A) The floor area of the laundry room
B) The peak hourly demand in gallons of hot water at the required temperature
C) The voltage available at the service panel
D) The number of washing machines
**Answer: B**
**Explanation:** Sizing is based on the **peak hourly demand**, calculated using fixture
counts and demand factors from the UPC (or manufacturer specs for specific appliances),
not just the number of fixtures.
According to UPC requirements, what is the minimum slope for a 4-inch diameter
horizontal drain pipe installed inside a building?
A) 1/16 inch per foot
B) 1/8 inch per foot
, C) 1/4 inch per foot
D) 1/2 inch per foot
**Answer: B**
**Explanation:** UPC Table 704.1 specifies the minimum slope for a 4-inch diameter drain
pipe is **1/8 inch per foot (1%)**.
In a multi-story commercial building, what device must be installed to prevent excessive
static pressure on the lower floors in the domestic water supply system?
A) A check valve
B) A pressure-reducing valve (PRV)
C) An expansion tank
D) A vacuum breaker
**Answer: B**
**Explanation:** **Pressure-reducing valves (PRVs)** are required on individual floor
branches or zones where the static pressure from the height of the water column exceeds
80 psi (UPC 604.8) to prevent fixture damage and water hammer.
What is the minimum required number of water closets for a commercial office building
with 125 male employees and 125 female employees, according to the 2018 UPC?
A) 2 for men, 2 for women
B) 3 for men, 3 for women
C) 2 for men, 3 for women
D) 3 for men, 4 for women
**Answer: D**
**Explanation:** Using UPC Table 422.1: For 1-150 occupants, men require 1-3 water
closets (125 requires 3). Women require 1-4 water closets (125 requires 4). This is based on
the calculation for "Assembly" or "Office" occupancy.
Plumbing Exam LATEST QUESTIONS AND CORRECT ANSWERS GRADE A
What is the minimum required size for the drain outlet for a commercial garbage disposal
unit with a 1-1/2 horsepower motor, according to the Uniform Plumbing Code (UPC)?
A) 1-1/2 inches
B) 2 inches
C) 3 inches
D) 4 inches
**Answer: B**
**Explanation:** UPC 802.2.1 requires a drain outlet of not less than 2 inches for
commercial food waste grinders with motors of 1 horsepower or greater.
When sizing the water heater for a commercial laundry facility, what is the primary factor
that must be determined first?
A) The floor area of the laundry room
B) The peak hourly demand in gallons of hot water at the required temperature
C) The voltage available at the service panel
D) The number of washing machines
**Answer: B**
**Explanation:** Sizing is based on the **peak hourly demand**, calculated using fixture
counts and demand factors from the UPC (or manufacturer specs for specific appliances),
not just the number of fixtures.
According to UPC requirements, what is the minimum slope for a 4-inch diameter
horizontal drain pipe installed inside a building?
A) 1/16 inch per foot
B) 1/8 inch per foot
, C) 1/4 inch per foot
D) 1/2 inch per foot
**Answer: B**
**Explanation:** UPC Table 704.1 specifies the minimum slope for a 4-inch diameter drain
pipe is **1/8 inch per foot (1%)**.
In a multi-story commercial building, what device must be installed to prevent excessive
static pressure on the lower floors in the domestic water supply system?
A) A check valve
B) A pressure-reducing valve (PRV)
C) An expansion tank
D) A vacuum breaker
**Answer: B**
**Explanation:** **Pressure-reducing valves (PRVs)** are required on individual floor
branches or zones where the static pressure from the height of the water column exceeds
80 psi (UPC 604.8) to prevent fixture damage and water hammer.
What is the minimum required number of water closets for a commercial office building
with 125 male employees and 125 female employees, according to the 2018 UPC?
A) 2 for men, 2 for women
B) 3 for men, 3 for women
C) 2 for men, 3 for women
D) 3 for men, 4 for women
**Answer: D**
**Explanation:** Using UPC Table 422.1: For 1-150 occupants, men require 1-3 water
closets (125 requires 3). Women require 1-4 water closets (125 requires 4). This is based on
the calculation for "Assembly" or "Office" occupancy.
