Exam Cheat Sheet · Quick Reference

Mississippi Master Electrician

Mississippi  ·  PSI Services Contractor

Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
80
Passing score
70
Exam time
180 min
Administered by
PSI Services Contractor
Format
Reference materials allowed

Mississippi State Portion 80 questions

General Electrical Knowledge 6 Q · 8%
Service, Feeders, and Branch Circuits 10 Q · 12%
Grounding and Bonding 7 Q · 9%
Conductors and Cables 10 Q · 12%
Raceways and Boxes 7 Q · 9%
Special Occupancies and Equipment 7 Q · 9%
Electrical Power 6 Q · 8%
Motors 6 Q · 8%
Low Voltage 2 Q · 2%
Lighting 3 Q · 4%
Illuminated Signs 2 Q · 2%
Fire Detection and Alarm Systems 3 Q · 4%
Safety Information 5 Q · 6%
Overcurrent Protection 6 Q · 8%

Key Distinctions

Series Circuit (Total Resistance)vsParallel Circuit (Total Resistance)

In a series circuit, total resistance equals the sum of all individual resistances (RT = R1+R2+R3), while in a parallel circuit the total resistance is always LESS than the resistance of any single branch.

Ugly's Electrical References, Series Circuits
Continuous LoadvsNon-Continuous Load

A continuous load is one where maximum current is expected to continue for 3 hours or more; a non-continuous load does not sustain maximum current for that duration.

NEC Article 100
NEC Chapters 1–7vsNEC Chapter 8 (Communications Systems)

Chapters 1–7 apply broadly to all electrical installations, whereas Chapter 8 (Communications Systems) is NOT subject to Chapters 1–7 requirements except where specifically referenced within Chapter 8.

NEC 90.3
Arc-Flash Label (General Equipment, NEC 110.16(A))vsArc-Flash Label (Service Equipment ≥1200A, NEC 110.16(B))

General equipment in non-dwelling units requires a warning label for qualified persons; service equipment rated 1200A or more additionally requires a permanent label listing nominal voltage, available fault current, clearing time, and date applied — conductor sizes are NOT required.

NEC 110.16(A)
15-Ampere Plug FusevsHigher-Rated Plug Fuse

Plug fuses of 15A and lower are identified by a hexagonal window/cap configuration to distinguish them from fuses of higher ampere ratings, which do not use that shape.

NEC 240.50(C)
Circuit Breaker Handle Operated VerticallyvsCircuit Breaker Handle Operated Horizontally or Rotationally

When a switchboard circuit breaker handle operates vertically, the UP position is the closed (ON) position; this directional requirement does not apply to horizontal or rotational handles.

OSHA 1926.404(e)(1)(vi)(B)
Small-Appliance Branch Circuit (Kitchen Countertop)vsGeneral-Purpose Branch Circuit

Kitchen countertop receptacles must be served by at least two 20-ampere small-appliance branch circuits per NEC 210.11(C)(1); a general-purpose 15-ampere circuit is NOT permitted for this use.

NEC 210.11(C)(1), 210.52(B)
Optional Dwelling Calculation — First 10 kVA (NEC 220.82(B))vsOptional Dwelling Calculation — Remainder Above 10 kVA (NEC 220.82(B))

The first 10 kVA of the general load is calculated at 100%, while any amount above 10 kVA is calculated at only 40%.

NEC 220.82(B)
Overhead Clearance — Pedestrian-Only Areas (≤150V to Ground)vsOverhead Clearance — Areas Subject to Truck Traffic

Open conductors not exceeding 150V to ground in pedestrian-only areas need only 3.0 m (10 ft) of clearance, while conductors over public streets and truck-traffic areas require 5.5 m (18 ft).

NEC 225.18(1)
NEC Informational NotesvsNEC Mandatory Rules

Informational notes are included for explanatory purposes only and are NOT enforceable, whereas mandatory rules (shall/shall not language) are legally binding requirements of the Code.

NEC 90.5(C)
Multiwire Branch Circuit DisconnectvsSingle Branch Circuit Disconnect

A multiwire branch circuit must have a means that simultaneously disconnects ALL ungrounded conductors at the point of origin, whereas a single branch circuit requires only one disconnect for its one ungrounded conductor.

NEC 210.4(B)
Termination Rating for Circuits ≤100AvsTermination Rating for Circuits >100A (NEC 110.14(C)(1)(b))

Equipment terminations for circuits over 100 amperes (or conductors larger than 1 AWG) must use conductors rated 75°C (167°F) unless listed for higher; circuits 100A and below may use 60°C-rated conductor ampacity at terminals.

NEC 110.14(C)(1)(b)

Key Terms

Purpose of the NEC (NEC 90.1(A)) NEC 90.1(A)
The practical safeguarding of persons and property from hazards arising from the use of electricity; NOT a design specification or instruction manual for untrained persons.
NEC Code Structure — Chapter 8 Independence (NEC 90.3) NEC 90.3
Chapter 8 (Communications Systems) is NOT subject to the requirements of Chapters 1 through 7 except where those requirements are specifically referenced in Chapter 8.
Interrupting Rating Requirement (NEC 110.9) NEC 110.9
Equipment intended to interrupt current at fault levels must have an interrupting rating at nominal circuit voltage at least equal to the current available at its line terminals.
High-Leg (Wild-Leg) Conductor Color (NEC 110.15) NEC 110.15
On a 4-wire delta system with the midpoint of one phase winding grounded, the conductor with the higher phase voltage to ground must be permanently marked orange.
Arc-Flash Hazard Warning Label — Service Equipment ≥1200A (NEC 110.16(B)) NEC 110.16(B)
Permanent labels on service equipment rated 1200A or more in non-dwelling units must show nominal system voltage, available fault current, clearing time of overcurrent devices, and the date applied.
Conductor Termination Temperature Rating >100A (NEC 110.14(C)(1)(b)) NEC 110.14(C)(1)(b)
Termination provisions for equipment rated over 100 amperes or marked for conductors larger than 1 AWG shall use only conductors rated 75°C (167°F) unless listed for higher temperatures.
Wooden Plugs Prohibited (NEC 110.13(A)) NEC 110.13(A)
Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials shall NOT be used to mount electrical equipment.
Reconditioned Equipment Marking (NEC 110.21(A)(2)) NEC 110.21(A)(2)
Reconditioned equipment must be labeled with the reconditioning organization's name, date of reconditioning, identified as 'reconditioned,' and the original listing mark must be removed.
Small-Appliance Branch Circuits — Dwelling Unit (NEC 210.11(C)(1)) NEC 210.11(C)(1)
A minimum of two 20-ampere small-appliance branch circuits must be provided for all kitchen countertop and related receptacle outlets in a dwelling unit.
Ampacity (NEC Article 100) NEC Article 100
The maximum current, in amperes, that a conductor can carry continuously under conditions of use without exceeding its temperature rating.
Continuous Load (NEC Article 100) NEC Article 100
A load where the maximum current is expected to continue for 3 hours or more.
NEC Informational Notes (NEC 90.5(C)) NEC 90.5(C)
Explanatory material included in the Code for informational purposes only; informational notes are NOT enforceable requirements.
Maximum Disconnects per Building Supply (NEC 225.33(A)) NEC 225.33(A)
Not more than six switches or six circuit breakers are permitted as the disconnecting means for each feeder supply to a building or structure.
Minimum Branch-Circuit Rating — Electric Range ≥8¾ kW (NEC 210.19(A)(3)) NEC 210.19(A)(3)
Household electric ranges rated 8¾ kW or more require a minimum branch-circuit rating of 40 amperes.
Commercial Kitchen Equipment Demand Factor (NEC Table 220.56) NEC Table 220.56
For 6 or more pieces of thermostatically controlled kitchen equipment (non-dwelling), a 65% demand factor may be applied to the total connected load.
Ohm's Law Ugly's Electrical References, Ohm's Law, Page 1
The relationship between current (I), voltage (E), and resistance (R): I = E/R; E = I×R; R = E/I; also expressed with power as P = E×I.

Formulas to Know

Ohm's Law — CurrentI = E / R
Ohm's Law — VoltageE = I × R
Power — Current from Watts & VoltageI = P / E
Series Circuit — Total ResistanceRT = R1 + R2 + R3 + ...
Three-Phase KilowattsKW = (E × I × PF × 1.73) / 1000
Dwelling Unit Optional Load Calc (NEC 220.82(B))Total Load = (First 10 kVA × 1.00) + (Remainder × 0.40)
Existing Dwelling Load Calc — No New HVAC (NEC 220.83(A))Total Load = (First 8 kVA × 1.00) + (Remainder × 0.40)
General Lighting Demand — Dwelling (NEC Table 220.42)First 3,000 VA at 100%; next 117,000 VA at 35%; remainder at 25%
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