Master Electrician (NEC) — All Questions
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56 questions
An indoor dry-type transformer rated 45 kVA with standard (Class 105) insulation must maintain what minimum separation from combustible material unless otherwise protected?
- a.18 in
- b.3 in
- c.12 in✓
- d.6 in
2023 NEC 450.21(A): dry-type transformers 112.5 kVA and under must be separated at least 12 in from combustible material unless the unit has a listed fire-resistant barrier or Class 155 (or higher) insulation.
Which value from a motor nameplate must be used with the tables to size branch-circuit short-circuit protection and conductors, per 430.6(A)?
- a.the nameplate full-load amperes
- b.the service-factor amps
- c.the locked-rotor current
- d.the table full-load current, not the nameplate current rating✓
2023 NEC 430.6(A)(1): for general motor applications, the full-load current values in Tables 430.247-430.250 (not the nameplate FLA) are used to size conductors and short-circuit/ground-fault protection. Overload protection uses the nameplate FLA.
The disconnecting means for air-conditioning or refrigerating equipment with a motor-compressor must be located:
- a.only at the main service panel
- b.inside a locked mechanical room only
- c.at least 25 ft away
- d.within sight from and readily accessible from the equipment✓
2023 NEC 440.14: the disconnect must be within sight from, and readily accessible from, the air-conditioning or refrigerating equipment.
How many overload (running-protection) units are required for a three-phase alternating-current motor?
- a.one
- b.three✓
- c.four
- d.two
2023 NEC Table 430.37: a three-phase AC motor requires three overload units, one in each phase.
In patient care spaces, grounding of receptacles and fixed electrical equipment must be accomplished by:
- a.an isolated ground only
- b.the metal raceway alone as the only ground path
- c.the grounded (neutral) conductor
- d.an insulated copper equipment grounding conductor plus a metal raceway or cable armor (redundant ground)✓
2023 NEC 517.13: patient care spaces require redundant grounding - an insulated copper EGC AND a metallic raceway or cable that itself qualifies as a grounding path.
The disconnecting means for a motor must have an ampere rating of at least what percentage of the motor full-load current?
- a.115%✓
- b.125%
- c.100%
- d.110%
2023 NEC 430.110(A): the disconnecting means for a motor circuit must be rated at least 115% of the motor full-load current.
How hard is the exam?
Master electrician licensing is state-administered and NEC-based, so format varies by state. In Texas, for example, the exam has two open-book portions (2023 NEC) — 75 NEC-knowledge items and 33 calculation items (108 total) — each needing 70% to pass, for a $78 fee. Electricians earn a median of about $62,350/year (BLS, May 2024).
- Recommended study hours
- 80-150 hours for most — master exams add heavier calculations and code-application depth over journeyman.
- Published pass rate
- 19.08% (the source does not say which attempts it counts) (n = 3,946); 22.21% (the source does not say which attempts it counts) (n = 3,472) — Texas TDLR, FY 2025. Read those as two exams, not one: TDLR has no row called “Master Electrician”, only “Master Calculations” (the first figure) and “Master NEC” (the second). Anyone quoting a single 19% Texas master pass rate has silently dropped half the exam. Licensing is state by state, so this is Texas only.Source: Texas TDLR — Electrician Exam Statistics, Fiscal Year 2025
- Where to focus first
- Services, service equipment and separately derived systems is among the heaviest areas (about 18% in Texas), plus the load-calculation portion.
Fees and salaries are approximate and change over time. The pass rate above is quoted from the source linked beside it, for the period that source covers — where we have not checked a source, we say so and give no number.