Iowa Class A Master Electrician Exam Newest
(2026 Update) Actual Practice Questions – Set
100 Most Common Exam Questions And
Answers In Details 100% Verified Exam
1.
A 120/240V single-phase service supplies a dwelling with calculated load of
18,400 VA. What is the minimum service disconnect rating required?
A) 60A
B) 80A
C) 100A
D) 125A
✔ C) 100A
Rationale: 18,400 VA ÷ 240V = 76.7A; next standard size is 100A per NEC sizing
rules.
2.
According to NEC, the maximum voltage drop recommended for branch circuits to
ensure efficiency is:
A) 3%
B) 5%
C) 10%
D) 2%
,✔ A) 3%
Rationale: NEC recommends 3% maximum voltage drop on branch circuits for
proper equipment performance.
3.
What is the minimum size copper conductor required for a 40A continuous load?
A) 10 AWG
B) 12 AWG
C) 8 AWG
D) 14 AWG
✔ A) 10 AWG
Rationale: Conductors must be sized at 125% of continuous load; 40A × 125% =
50A → 10 AWG copper.
4.
A motor draws 28A at full load. What is the minimum conductor ampacity
required?
A) 28A
B) 30A
C) 35A
D) 40A
✔ C) 35A
Rationale: Motor conductors must be sized at 125% of FLC: 28A × 1.25 = 35A.
5.
Which device protects against ground-fault leakage in dwelling unit bathrooms?
,A) AFCI
B) GFCI
C) Fuse
D) Thermal relay
✔ B) GFCI
Rationale: GFCI devices protect personnel from ground-fault current in wet
locations.
6.
What is the maximum number of 12 AWG THHN conductors allowed in a ¾ inch
EMT conduit?
A) 9
B) 12
C) 16
D) 7
✔ A) 9
Rationale: Conduit fill tables limit 12 AWG conductors to 9 in ¾ inch EMT at 40%
fill.
7.
A 480V three-phase motor has a nameplate FLA of 46A. What is the maximum size
inverse-time breaker permitted?
A) 60A
B) 70A
C) 80A
D) 100A
, ✔ C) 80A
Rationale: NEC allows up to 175–250% for motor protection; 46 × 2.5 = 115A
max, next standard commonly 80A depending on table rules.
8.
The primary purpose of equipment grounding is to:
A) Carry normal load current
B) Stabilize voltage
C) Provide a fault current path
D) Reduce resistance
✔ C) Provide a fault current path
Rationale: Grounding ensures fault current returns to source to trip protective
devices.
9.
What is the resistance of a circuit with 120V and 12A current?
A) 10Ω
B) 12Ω
C) 8Ω
D) 14Ω
✔ A) 10Ω
Rationale: Ohm’s Law R = V/I = 120/12 = 10Ω.
10.
Which wiring method is permitted in hazardous locations?
(2026 Update) Actual Practice Questions – Set
100 Most Common Exam Questions And
Answers In Details 100% Verified Exam
1.
A 120/240V single-phase service supplies a dwelling with calculated load of
18,400 VA. What is the minimum service disconnect rating required?
A) 60A
B) 80A
C) 100A
D) 125A
✔ C) 100A
Rationale: 18,400 VA ÷ 240V = 76.7A; next standard size is 100A per NEC sizing
rules.
2.
According to NEC, the maximum voltage drop recommended for branch circuits to
ensure efficiency is:
A) 3%
B) 5%
C) 10%
D) 2%
,✔ A) 3%
Rationale: NEC recommends 3% maximum voltage drop on branch circuits for
proper equipment performance.
3.
What is the minimum size copper conductor required for a 40A continuous load?
A) 10 AWG
B) 12 AWG
C) 8 AWG
D) 14 AWG
✔ A) 10 AWG
Rationale: Conductors must be sized at 125% of continuous load; 40A × 125% =
50A → 10 AWG copper.
4.
A motor draws 28A at full load. What is the minimum conductor ampacity
required?
A) 28A
B) 30A
C) 35A
D) 40A
✔ C) 35A
Rationale: Motor conductors must be sized at 125% of FLC: 28A × 1.25 = 35A.
5.
Which device protects against ground-fault leakage in dwelling unit bathrooms?
,A) AFCI
B) GFCI
C) Fuse
D) Thermal relay
✔ B) GFCI
Rationale: GFCI devices protect personnel from ground-fault current in wet
locations.
6.
What is the maximum number of 12 AWG THHN conductors allowed in a ¾ inch
EMT conduit?
A) 9
B) 12
C) 16
D) 7
✔ A) 9
Rationale: Conduit fill tables limit 12 AWG conductors to 9 in ¾ inch EMT at 40%
fill.
7.
A 480V three-phase motor has a nameplate FLA of 46A. What is the maximum size
inverse-time breaker permitted?
A) 60A
B) 70A
C) 80A
D) 100A
, ✔ C) 80A
Rationale: NEC allows up to 175–250% for motor protection; 46 × 2.5 = 115A
max, next standard commonly 80A depending on table rules.
8.
The primary purpose of equipment grounding is to:
A) Carry normal load current
B) Stabilize voltage
C) Provide a fault current path
D) Reduce resistance
✔ C) Provide a fault current path
Rationale: Grounding ensures fault current returns to source to trip protective
devices.
9.
What is the resistance of a circuit with 120V and 12A current?
A) 10Ω
B) 12Ω
C) 8Ω
D) 14Ω
✔ A) 10Ω
Rationale: Ohm’s Law R = V/I = 120/12 = 10Ω.
10.
Which wiring method is permitted in hazardous locations?
