General Knowledge
10%of exam
Installation Requirements
7-8%of exam
Listing + LabelingWorking SpaceWorkmanshipOSHA 1926Identification
Services + Feeders + Branch
17-18%of exam
Overcurrent Protection
5%of exam
Article 240Breaker SizingFuse Sizing240.4(D) Small WireNext-Size-Up
Grounding + Bonding
12-13%of exam
Article 250GEC SizingEGC SizingElectrodesBonding Jumpers
Conductors + Cables
10%of exam
Article 310 AmpacityInsulation TypesTerminal TempCorrection FactorsConductor Colors
Raceways + Boxes
12-13%of exam
Chapter 3 MethodsConduit FillBox Fill 314.16Support SpacingBend Limits
Hazardous Locations
12-13%of exam
Article 500Class I/II/IIIDivisionsSealsExplosion-Proof
Low Voltage + Comms
5%of exam
Article 725Article 760 AlarmArticle 800 CommsPower-LimitedSeparation Rules
Lighting + Signs + Equipment
7-8%of exam
Article 410 LuminairesArticle 600 SignsArticle 422 AppliancesClearancesListed Equipment
Quick Facts
- Exam
- TN LLE
- Provider
- Prov
- Questions
- 40 MCQ
- Time
- 2 hours
- Pass
- 73% (29 of 40)
- Format
- Open book
- Code
- NEC 2017
- Fee
- $53 (Prov)
- License scope
- Under $25,000
- Retakes
- Unlimited, no wait
Ohm's Law Triangle
V on top; I and R below
V = I x RI = V/RR = V/I
Series vs Parallel
Series
- One current path
- Resistances add
- Drops sum to source
Parallel
- Shared voltage
- Currents add
- Resistance below smallest
One path vs many
NEC Layout
- Article 90
- Purpose + scope
- Article 100
- Definitions
- Chapters 1-4
- General rules
- Chapter 5
- Special occupancies
- Chapter 6
- Special equipment
- Chapter 7
- Special conditions
- Chapter 8
- Communications
- Chapter 9
- Tables + notes
NEC Chapter Map
90 scope, 100 defs, 110 install, then chapters
90: purpose100: definitions110: install rulesCh 3: methods
Ohm's Law + Power
- V = IR
- Ohm's law
- I = V/R
- Solve current
- P = VI
- Resistive power
- P = I2R
- Power from current
- E = Pt
- Energy over time
- kWh
- Billing energy unit
- milli (m)
- x0.001
Installation + Safety
- Listed
- Third-party approved
- Labeled
- Marked by evaluator
- Working space
- 3 ft typical110.26
- Readily accessible
- Reach without obstacles
- OSHA 1926
- Job-site safety
- Disconnect marking
- Identify purpose
- Guarding
- Protect live parts
GFCI vs AFCI
GFCI
- Shock protection
- Ground-fault current
- Wet + damp areas
AFCI
- Fire protection
- Arc-fault current
- Dwelling living areas
Shock vs fire
GFCI vs AFCI Picker
- Kitchen countertop receptacle→GFCI required(210.8(A)(6))
- Bathroom receptacle→GFCI required(210.8(A)(1))
- Garage or outdoor receptacle→GFCI required(210.8(A)(2)(5))
- Basement or laundry area→GFCI required(210.8(A)(7)(10))
- Dwelling bedroom circuit→AFCI required(210.12(A))
- Shock and arc risk both→Use dual-function device(Combination protection)
- Extend circuit into covered area→AFCI still applies(210.12(A) extension)
- Commercial kitchen countertop→GFCI required(210.8(B))
Load Calculations
- General lighting
- 3 VA/ft2220.12
- Small appliance
- 1500 VA each, min 2
- Laundry circuit
- 1500 VA, one 20A
- Range demand
- Table 220.55
- Dryer demand
- 5000W or nameplate220.54
- Continuous load
- Use 125%
- Service calc
- Standard or optional method
Branch Circuit vs Feeder
Branch circuit
- After final OCPD
- Supplies outlets
- Article 210
Feeder
- Before final OCPD
- Supplies panels
- Article 215
After vs before OCPD
Services + Feeders + Branch
- Article 230
- Service conductors
- Article 215
- Feeder sizing
- Article 210
- Branch circuits
- Service disconnect
- Max 6 handles
- Feeder OCPD
- At least calc load
- Multiwire circuit
- Shared neutral
- Receptacle spacing
- 12 ft rule210.52
GFCI + AFCI Locations
- GFCI
- Kitchen countertops
- GFCI
- Bathrooms
- GFCI
- Garage + outdoor
- GFCI
- Basement + laundry
- AFCI
- Bedrooms + living areas
- Dual-function
- Shock + arc
Ampacity vs OCPD Rating
Ampacity
- Conductor current limit
- Table 310.15(B)(16)
- Heat-based rating
OCPD rating
- Breaker or fuse size
- Table 240.6(A)
- Protects the conductor
Wire limit vs device size
OCPD + Conductor Picker
- Continuous load calculated→Apply 125% factor(210.19(A))
- Conductor size needed→Read Table 310.15(B)(16)(Match ampacity)
- Terminals rated 60C→Use 60C column(Typical 100A or less)
- Terminals rated 75C→Use 75C column(Typical over 100A)
- Ampacity between std sizes→Round up OCPD(240.4(B))
- 14/12/10 AWG copper→Cap at 15/20/30A(240.4(D) overrides)
- Motor branch circuit→Apply Table 430.52(Not general OCPD rule)
- Over 3 current-carrying conductors→Apply adjustment factor(310.15(C)(1))
Overcurrent Protection
- Article 240
- Overcurrent devices
- Standard sizes
- 240.6(A) list
- Next-size-up
- 240.4(B) rounding
- Small conductor rule
- 240.4(D) caps size
- Motor OCPD
- Table 430.52 multiplier
- Tap rule
- 240.21 exceptions
Grounding vs Bonding
Grounding
- Connects to earth
- Stabilizes voltage
- GEC route
Bonding
- Joins metal parts
- Creates fault path
- EGC route
Earth vs continuity
Grounding Electrode Picker
- Metal water pipe 10ft+→Use as electrode(250.52(A)(1))
- Concrete-encased rebar present→Use ufer ground(250.52(A)(3))
- Ground ring 20ft or more→Use as electrode(250.52(A)(4))
- Single rod exceeds 25 ohms→Add second rod(250.53(A)(2))
- Multiple electrodes present→Bond into one system(250.50)
- No qualifying electrode present→Install made electrode(Rod, plate, or ring)
Grounding + Bonding
- GEC sizing
- Table 250.66
- EGC sizing
- Table 250.122
- Water pipe electrode
- 10 ft in earth250.52(A)(1)
- Concrete-encased electrode
- Ufer ground250.52(A)(3)
- Ground rod
- 8 ft minimum
- Rod resistance
- 25 ohm or add rod250.53(A)(2)
- Bonding jumper
- Table 250.102(C)(1)
- Main bonding jumper
- Neutral-to-ground bond
Wire Color Code
White/gray grounded; green/bare ground; black hot
White/gray: neutralGreen/bare: EGCBlack/red: ungrounded
THHN vs THWN
THHN
- Dry locations only
- 90C rated
- Thermoplastic + nylon
THWN
- Wet locations rated
- 75C typical
- Moisture-resistant nylon
Dry vs wet rating
Conductors + Ampacity
- Ampacity table
- 310.15(B)(16)
- 60C terminals
- Typical 100A or less
- 75C terminals
- Typical over 100A
- THHN
- Dry, 90C rated
- THWN
- Wet-rated
- Adjustment factor
- Over 3 current-carrying wires
- White/gray
- Grounded conductor
- Green/bare
- Equipment grounding conductor
Conduit Fill Steps
1 wire 53%; 2 wires 31%; 3+ 40%
1 conductor: 53%2 conductors: 31%3+ conductors: 40%
Raceway + Conduit Fill
- 1 conductor
- 53% fill
- 2 conductors
- 31% fill
- 3+ conductors
- 40% fill
- EMT
- Thin-wall metal raceway
- PVC
- Nonmetallic raceway
- Burial depth
- Table 300.5
Box Fill Rules
- Box fill
- Table 314.16(B)
- Device yoke
- Counts as 2
- Internal clamp
- Counts as 1
- EGCs
- Counted as 1 total
- Fixture stud/hickey
- Counts as 1
Hazard Class Order
I gas, II dust, III fibers
Class I: gas/vaporClass II: dustClass III: fibers/flyings
Hazardous Location Classes
- Class I
- Flammable gas/vapor
- Class II
- Combustible dust
- Class III
- Ignitable fibers/flyings
- Division 1
- Normal hazard presence
- Division 2
- Abnormal/accidental presence
- Seal fitting
- Stops gas migration
- Explosion-proof
- Contains internal ignition
Low Voltage + Comms
- Article 725
- Class 1/2/3 circuits
- Power-limited
- Reduced fire/shock risk
- Article 760
- Fire alarm circuits
- Article 800
- Communications systems
- Separation rule
- Power vs low-voltage
Lighting + Signs + Equipment
- Article 410
- Luminaires
- Storage clearance
- 410.16 minimum
- Article 600
- Electric signs
- Sign disconnect
- 600.6 required
- Article 422
- Fixed appliances
- Listed equipment
- Follow install instructions
Common Traps
Ampacity vs OCPD
Ampacity rates the wire ≠ OCPD sizes the device
Grounding vs Bonding
Grounding connects to earth ≠ Bonding joins metal parts
Continuous vs Noncontinuous Load
Continuous runs 3+ hours ≠ Noncontinuous needs no 125%
Service vs Feeder
Service comes from utility ≠ Feeder follows service equipment
Class I vs Class II
Class I is gas/vapor ≠ Class II is dust
GFCI vs AFCI
GFCI stops shock ≠ AFCI stops arcing fires
Box Fill vs Conduit Fill
Box fill counts volume ≠ Conduit fill uses percent area
Last Minute
- 1.40 questions; 2-hour time limit
- 2.73% passing score (29 of 40)
- 3.NEC 2017 controls all answers
- 4.Open book: NEC + Ugly's + OSHA
- 5.LLE license caps at $25,000
- 6.Unlimited retakes, no waiting period
- 7.GFCI = shock; AFCI = arc
- 8.Continuous loads always get 125%
- 9.Table 310.15(B)(16) sets ampacity
- 10.Table 250.122 sizes grounding conductors
- 11.Table 250.66 sizes grounding electrode conductor
- 12.Conduit fill: 53/31/40 percent
- 13.Motor OCPD uses Table 430.52
- 14.Confirm current NEC edition first
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