| Branch circuits (Art. 210) |
Receptacle spacing, required circuits, GFCI and AFCI locations |
Lots of small rules that read almost the same. Easy to answer from memory and be a code cycle out of date. |
| Load calculations (Art. 220) |
Dwelling and commercial service and feeder loads, demand factors |
The single heaviest calculation topic. Multi step, and one wrong demand factor kills the whole answer. |
| Services (Art. 230) |
Service conductor sizing, disconnect rules, clearances |
Frequently paired with a load calculation, so an early arithmetic slip shows up twice. |
| Overcurrent protection (Art. 240) |
Breaker and fuse sizing, next standard size rules, tap rules |
The rounding rules have exceptions, and the exceptions are exactly what gets tested. |
| Grounding and bonding (Art. 250) |
Equipment grounding conductor and grounding electrode conductor sizing |
Two similar sounding conductors, two different tables. Grabbing the wrong table is a classic miss. |
| Conductors (Art. 310) |
Ampacity, temperature correction, conduit fill adjustment, terminations |
Correction and adjustment factors stack, and the termination temperature limit is easy to forget. |
| Boxes (Art. 314) |
Box fill calculations and conductor counting |
Free points if you drilled it, lost points if you guess which items count as one and which count as two. |
| Motors (Art. 430) |
Motor conductor sizing, overload and short circuit protection |
Uses table values rather than nameplate amps for some steps, which trips candidates who work from the field habit. |
| Chapter 9 tables and Annex C |
Raceway fill, conductor dimensions, voltage drop inputs |
Pure lookup speed. Candidates who have not tabbed these burn minutes they needed for the calculation block. |