Exam Cheat Sheet · Quick Reference
Texas Journeyman Electrician Calculations Portion
Texas · 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
26
Passing score
70%
Exam time
110 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Texas State Portion 26 questions
Calculations and Theory
2 Q · 8%
Dwelling unit load calculations using standard and optional methods (Articles 220 Parts III and IV)Branch-circuit load calculations including minimum unit loads, receptacle loads, and outlet loads (Article 220 Part II)Conductor ampacity selection and correction/adjustment factors for temperature and number of conductors (Article 310)Motor branch-circuit conductor sizing and feeder calculations including 125% rule and multiple motor loads (Article 430 Parts II and V)Feeder and service neutral load calculations and permitted reductions (Section 220.61)Demand factors for household electric ranges, cooking appliances, and clothes dryers (Sections 220.54 and 220.55)Overcurrent protective device ratings and standard ampere ratings for branch circuits and feeders (Article 240)Multifamily dwelling, school, and commercial occupancy optional load calculation methods (Sections 220.84 through 220.88)
Electrical Services, Service Equipment, and Separately Derived Systems
4 Q · 17%
Service conductor ampacity sizing and minimum size requirements (Articles 230.23, 230.31, 230.42)Service disconnecting means rating and number of disconnects (Articles 230.71, 230.79, 230.80)Grounding electrode conductor sizing using Table 250.66Main bonding jumper and system bonding jumper sizing using Table 250.102(C)(1)Service entrance conductor sizing for continuous and noncontinuous loads (Article 230.42)Ground-fault protection of equipment requirements for solidly grounded wye services (Article 230.95)Separately derived system grounding and bonding calculations (Article 250.30)Transformer overcurrent protection calculations using Tables 450.3(A) and 450.3(B)
Electrical Feeders
3 Q · 12%
Minimum feeder conductor ampacity for continuous and noncontinuous loads (125% rule)Feeder load calculations using demand factors for dwelling units and multifamily buildingsFeeder overcurrent protection rating requirementsFeeder neutral load calculations and permitted reductionsOptional feeder load calculation methods for dwelling units and schoolsAmpacity correction and adjustment factors applied to feeder conductorsGround-fault protection requirements for feeder disconnects rated 1000 amperes or moreFeeder tap conductor rules (10-foot, 25-foot, and outside tap provisions)
Branch Circuit Calculations and Conductors
4 Q · 17%
Minimum conductor ampacity and sizing for continuous and noncontinuous loads (210.19, 220.11)Branch circuit ratings and permissible loads by circuit size (210.18, 210.23, 210.24)Overcurrent protection sizing for branch circuits including 125% continuous load rule (210.20, 240.4, 240.6)Ampacity tables and correction/adjustment factors for temperature and number of conductors (310.15, 310.16, Table 310.15(C)(1))Dwelling unit branch circuit load calculations including general lighting, small appliance, and laundry loads (220.41, 220.52)GFCI and AFCI protection requirements by location and occupancy type (210.8, 210.12)Receptacle outlet ratings and placement requirements for dwelling and non-dwelling occupancies (210.21, 210.52)Conductor identification requirements for grounded, ungrounded, and equipment grounding conductors (200.6, 210.5, 310.6)
Electrical Wiring Methods and Electrical Materials
2 Q · 8%
Conductor ampacity tables and temperature ratings (Table 310.16, 310.17)Ambient temperature correction factors for conductor ampacity (Table 310.15(B)(1)(1))Adjustment factors for more than three current-carrying conductors in a raceway (Table 310.15(C)(1))Minimum underground burial depth requirements by wiring method and location (Table 300.5(A))Conductor sizing for single-phase dwelling services and feeders (Table 310.12(A))Conductor support spacing in vertical raceways (Table 300.19(A))Physical protection requirements for cables and raceways through wood members and framing (300.4)Permitted wiring methods in ducts and plenums used for environmental air (300.22)
Electrical Equipment and Devices
2 Q · 8%
Motor branch-circuit conductor sizing and ampacity calculations (Article 430)Motor branch-circuit short-circuit and ground-fault protective device ratings using Table 430.52(C)(1)Overload protection sizing for continuous-duty motors (430.32)Conductors supplying multiple motors or combined motor and non-motor loads (430.24)Hermetic refrigerant motor-compressor branch-circuit sizing and protection (Article 440)Transformer overcurrent protection ratings using Tables 450.3(A) and 450.3(B)Generator conductor ampacity and overcurrent protection requirements (Article 445)Industrial control panel supply conductor ampacity and overcurrent protection rating (Article 409)
Motors and Generators
2 Q · 8%
Motor branch-circuit conductor sizing (125% rule, Table 430.247–430.250)Branch-circuit short-circuit and ground-fault protective device rating or setting (Table 430.52)Motor overload protection sizing and selection (430.32, service factor and temperature rise percentages)Feeder conductor sizing for multiple motors (430.24 summation method)Disconnecting means rating and location requirements for motors (430.102, 430.109, 430.110)Generator output conductor ampacity and overcurrent protection (445.12, 445.13)Hermetic refrigerant motor-compressor branch-circuit protection and conductor sizing (440.22, 440.32)Locked-rotor current code letters and kVA/hp calculations (Table 430.7(B))
Electrical Control Devices and Disconnecting Means
1 Q · 4%
Motor disconnecting means rating, type, and location requirements (Article 430 Part IX)Motor branch-circuit short-circuit and ground-fault protective device rating calculations using Table 430.52(C)(1)Motor overload protection sizing for continuous-duty motors (430.32 percentage thresholds)Conductor ampacity calculations for single and multiple motors (430.22 and 430.24)Service disconnecting means rating, location, and number of disconnects (Article 230 Part VI)Switch ratings and permitted uses by load type (Article 404.14 AC/DC snap switch classifications)Industrial control panel conductor ampacity and overcurrent protection rating calculations (Article 409)Air-conditioning and refrigerating equipment disconnecting means rating and branch-circuit protection (Article 440)
Special Occupancies, Equipment, and Conditions
3 Q · 12%
Classification of hazardous locations by Class, Division, and Group (Classes I, II, III; Divisions 1 and 2; Groups A–G)Protection techniques for hazardous locations (explosionproof, dust-ignitionproof, intrinsic safety, purged/pressurized, nonincendive, dusttight, etc.)Wiring methods permitted in Class I, II, and III Division 1 and 2 locations (conduit types, cable types, sealing requirements)Equipment marking requirements including temperature classification (T-codes) and approval for class, division, and groupSealing and drainage requirements for conduit and cable systems in hazardous locationsGrounding and bonding requirements specific to hazardous classified locationsArea classification and wiring/equipment requirements for specific occupancies (commercial garages, motor fuel dispensing facilities, aircraft hangars, cannabis oil facilities)Intrinsically safe systems installation requirements including conductor separation, sealing, and identification (Article 504)
Renewable Energy Technologies
1 Q · 4%
PV source circuit maximum voltage calculation using temperature correction factors (Table 690.7(A))Maximum circuit current calculation for PV systems (690.8(A)) and 125% conductor ampacity sizingOvercurrent protection device ratings for PV system dc circuits (690.9(B))Busbar and feeder sizing for load-side power source connections (705.12(A) and 705.12(B))Wind electric system circuit sizing and overcurrent device ratings at 125% of maximum current (694.12(B))Energy storage system circuit sizing and overcurrent device ratings at 125% of maximum current (706.30 and 706.31)Conductor ampacity sizing for interconnected power source output circuits (705.28(B))Equipment grounding conductor sizing for PV systems using Table 250.122 (690.45)
Key Distinctions
Continuous loadvsNon-continuous load
Continuous load must be multiplied by 125% when sizing conductors and overcurrent devices, while non-continuous load is counted at 100%.
NEC 2026 Section 215.4(A)(1)(a)Motor branch-circuit conductors (430.22)vsMotor feeder conductors (430.24)
A branch circuit to a single motor is sized at 125% of that motor's table FLC, while a feeder to multiple motors is sized at 125% of the largest motor FLC plus 100% of all other motor FLCs.
NEC 2026 Table 430.248, Section 430.22Table FLC (Tables 430.248/430.250)vsMotor nameplate current
Per 430.6(A)(1) conductor, disconnect, and branch-circuit protection sizing use the table FLC, but overload protection per 430.32 is based on the motor nameplate full-load amperes.
NEC 2026 Table 430.250, Section 430.22Motor conductor sizing at 125% FLCvsMotor disconnect sizing at 115% FLC
Conductors use 125% of FLC (430.22) while the disconnecting means must be rated at least 115% of FLC (430.110(A)); 125% of FLC is a distractor for disconnect questions.
NEC 2026 Table 430.250, Section 430.110Time-delay (dual-element) fuse — 175% of FLCvsInverse-time circuit breaker — 250% of FLC
Table 430.52 permits branch-circuit short-circuit/ground-fault protection at 175% of FLC for dual-element fuses versus 250% of FLC for inverse-time breakers on AC squirrel cage motors.
NEC 2026 Table 430.250, Table 430.52, Section 240.6Next higher standard OCPD size permitted (general rule, 430.52(C)(1))vsNext lower standard OCPD size used
430.52(C)(1) generally permits rounding up to the next standard size in 240.6(A) when the calculation doesn't land on a standard size — the verified answer for 52A × 175% = 91A rounds UP to 100A even though the question says to disregard exceptions; in the 88A × 175% = 154A question the verified answer instead used the next LOWER standard size, 150A.
NEC 2026 Table 430.250, Table 430.52, Section 240.6Single-phase voltage drop formulavsThree-phase voltage drop formula
Single-phase uses VD = (2 × K × I × D)/CM, while the three-phase version substitutes the 1.732 factor for the 2 — a common distractor answer.
NEC 2026 Chapter 9, Table 8Single-phase current I = VA ÷ EvsThree-phase current I = VA ÷ (E × 1.732)
Three-phase loads divide by line voltage times the square root of 3 (1.732); using the single-phase formula on a 3-phase load roughly doubles the answer.
NEC 2026 Section 215.4(A)(1)Straight pull box (314.28(A)(1))vsAngle pull box (314.28(A)(2))
Straight pulls require 8 times the largest raceway trade diameter, while angle pulls require 6 times the largest raceway trade diameter plus the sum of the other raceway trade diameters on that wall.
NEC 2026 Section 314.28Ambient temperature correction factor (Table 310.15(B)(2)(a))vsConductor adjustment factor (Table 310.15(B)(3)(a))
The correction factor is based on ambient temperature and the conductor's insulation rating, while the adjustment factor is based on the number of current-carrying conductors bundled in the raceway; both are applied to the base ampacity when they apply.
NEC 2026 Table 310.16, Table 310.15(B)(1)(1), Table 310.15(C)(1)90°C column of Table 310.16 (THHN)vs75°C column of Table 310.16 (THWN / 75°C terminations)
Derating calculations for THHN start from the 90°C base ampacity, but conductor selection for equipment with 75°C terminations (THWN) is made from the 75°C column.
NEC 2026 Table 310.16, Table 310.15(B)(1)(1), Table 310.15(C)(1)Round down (conduit fill)vsRound up (number of branch circuits)
Maximum conductors in a raceway are rounded down unless the decimal is 0.8 or greater (Chapter 9, Note 7), while the required number of branch circuits is always rounded up to the next whole circuit.
NEC 2026 Chapter 9, Table 4Key Terms
Continuous load factor (125%) NEC 2026 Section 215.4(A)(1)(a)
Feeder conductors must have ampacity not less than the non-continuous load plus 125% of the continuous load per NEC 215.2(A)(1)(a).
Branch-circuit conductor ampacity for continuous loads NEC 2026 Section 210.19
Per NEC 210.19(A)(1), branch-circuit conductors supplying a continuous load must have an ampacity not less than 125% of that continuous load.
Service-entrance conductor ampacity NEC 2026 Section 230.42
Per NEC 230.42(A), service conductors must have ampacity not less than 125% of the continuous loads plus 100% of the non-continuous loads.
Overcurrent device rating for continuous load (210.20(A)) NEC 2026 Section 210.20, 210.19
The rating of the overcurrent device must not be less than 125% of the continuous load, so the maximum continuous load on a 20A circuit is 16A.
Full-load current (FLC) NEC 2026 Table 430.250, Section 430.22
The motor current value taken from NEC Table 430.248 (single-phase) or Table 430.250 (three-phase), which must be used instead of nameplate current for conductor, disconnect, and branch-circuit protection sizing per 430.6(A)(1).
Motor overload protection (430.32(A)(1)) NEC 2026 Section 430.32
For a motor with a service factor of 1.15 or greater, the overload device must not exceed 125% of the motor nameplate full-load amperes.
Motor disconnecting means rating (430.110(A)) NEC 2026 Table 430.250, Section 430.110
The disconnect for a motor must be rated at least 115% of the motor's table full-load current.
Standard overcurrent device sizes (240.6(A)) NEC 2026 Table 430.250, Table 430.52, Section 240.6
The list of standard fuse and circuit breaker ratings (e.g., 90A, 100A, 150A, 175A) used to select the next higher or next lower size after a motor protection calculation.
Generator output conductors (445.13(A)) NEC 2026 Section 445.13(A)
Conductors from generator output terminals to the first distribution device containing overcurrent protection must have an ampacity not less than 115% of the generator nameplate current rating (where the generator lacks inherent overload-preventing design).
40% fill area (Chapter 9, Table 4) NEC 2026 Chapter 9, Table 4
The maximum permitted cross-sectional fill area for a raceway containing more than two conductors, compared against the total conductor area from Table 5 to pick the trade size.
Chapter 9, Note 7 (rounding) NEC 2026 Chapter 9, Table 4
When the conduit-fill calculation for the number of conductors results in a decimal of 0.8 or larger it may be rounded up; otherwise round down (e.g., 10.09 becomes 10 conductors).
Box fill volume allowances (314.16(B), Table 314.16(B)(1)) NEC 2026 Section 314.16(B), Table 314.16(B)(4)
Each 12 AWG conductor counts 2.25 cu in and each 14 AWG 2.00 cu in; up to four equipment grounding conductors count as one allowance based on the largest EGC, and each device yoke counts as twice the volume of the largest conductor connected to it.
Straight pull box minimum length (314.28(A)(1)) NEC 2026 Section 314.28
For straight pulls the box length must be at least 8 times the trade diameter of the largest raceway, e.g., 8 × 3" = 24 inches.
Angle pull minimum distance (314.28(A)(2)) NEC 2026 Section 314.28
For angle pulls the distance from the entry wall to the opposite wall must be at least 6 times the largest raceway trade diameter plus the sum of the trade diameters of the other raceways on that same wall.
PV inverter output circuit conductors (690.8) NEC 2026 Section 690.8, Section 215.4(A)(1)
PV system circuit conductors are treated as continuous loads, so the calculated circuit current is multiplied by 125% to set minimum conductor ampacity.
Ground-fault signal device setting (700.6(D)) NEC 2026 Section 700.7(D)
Required on solidly grounded wye emergency systems over 150V to ground with protective devices rated 1000A or more, with a maximum setting of 1200 amperes of ground-fault current.
Pull point (358.26, EMT bends) NEC 2026 Section 358.24(B) (EMT — number of bends in one run)
A conduit body or box that limits a run to 360° of bends between pull points; adding one allows each section on either side to have up to 360° of bends.
K constant for copper NEC 2026 Chapter 9, Table 8
The resistivity constant K = 12.9 used for copper conductors in the voltage drop formula, with conductor circular mils taken from Chapter 9, Table 8.
Formulas to Know
Minimum ampacity with continuous and non-continuous loads (feeders, services, branch circuits)
Min ampacity = (continuous load × 125%) + (non-continuous load × 100%); e.g., (48A × 1.25) + 30A = 90A; (80A × 1.25) + 30A = 130A; continuous only: 42A × 1.25 = 52.5AMaximum continuous load on a circuit and number of circuits required
Max continuous load = OCPD rating ÷ 1.25 (20A ÷ 1.25 = 16A); No. of circuits = (load VA × 1.25) ÷ (circuit V × circuit A), rounded UP (8,400 × 1.25 = 10,500 ÷ (277 × 20 = 5,540) = 1.895 → 2)Motor branch-circuit conductor ampacity (430.22)
Min ampacity = Table 430.248/430.250 FLC × 125%; e.g., 34A × 1.25 = 42.5A; 52A × 1.25 = 65A; 74.8A × 1.25 = 93.5A (then pick size from Table 310.16 75°C column)Motor feeder conductor ampacity (430.24)
Min ampacity = (largest motor FLC × 125%) + 100% of all other motor FLCs + other loads per 215.2(A)(1) (continuous other loads at 125%); e.g., (21 × 1.25) + 14 = 40.25A; (143 × 1.25) + (60 × 1.25) = 253.75AMotor branch-circuit short-circuit/ground-fault protection (Table 430.52)
Time-delay (dual-element) fuse = FLC × 175%; inverse-time CB = FLC × 250%; then go to the next HIGHER standard size in 240.6(A) per 430.52(C)(1), which is the general rule (34 × 2.5 = 85A → 90A; 65 × 2.5 = 162.5A → 175A; 52 × 1.75 = 91A → 100A even when exceptions are disregarded); one verified answer instead used the next LOWER standard size (88 × 1.75 = 154A → 150A)Motor overload, disconnect, and generator conductor multipliers
Overload (SF ≥ 1.15) = nameplate FLA × 125% (82A × 1.25 = 102.5A; 26A × 1.25 = 32.5A); Disconnect = Table FLC × 115% (65A × 1.15 = 74.8A); Generator conductors to first OCPD = nameplate current × 115% (187.5A × 1.15 = 215.6A)Adjusted (derated) conductor ampacity
Adjusted ampacity = base ampacity (Table 310.16, correct insulation column) × temperature correction factor (Table 310.15(B)(2)(a)) × conductor adjustment factor (Table 310.15(B)(3)(a)); e.g., 30A × 0.91 × 0.70 = 19.1A; 230A × 0.82 = 188.6A (no adjustment with only 3 CCC)Voltage drop, single-phase
VD = (2 × K × I × D) ÷ CM with K = 12.9 for copper, D = one-way distance, CM from Chapter 9 Table 8; e.g., (2 × 12.9 × 120 × 175) ÷ 105,600 = 5.1V; (2 × 12.9 × 16 × 100) ÷ 6,530 = 6.33VCircuit / transformer full-load current
3-phase: I = VA ÷ (E × 1.732) — 23,000 ÷ (208 × 1.732) = 63.9A; 75,000 ÷ (208 × 1.732) = 208.2A. Single-phase: I = VA ÷ E (line-to-line V) — 7,200 ÷ 240 = 30A; 45,000 ÷ 240 = 187.5ARaceway conduit fill sizing
Total fill = Σ (number of conductors × area from Chapter 9 Table 5); choose the smallest trade size whose 40% column in Chapter 9 Table 4 ≥ total fill. Max conductors = 40% fill area ÷ conductor area, rounded down unless decimal ≥ 0.8 (0.213 ÷ 0.0211 = 10.09 → 10)