NEC Cheat Sheet 2026

The 30 highest-yield NEC facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. The continuity of a grounded conductor in a multiwire branch circuit must not depend on which connection? → A device terminal such as a receptacle
2. What size service conductors are needed for a 190 A calculated load in a dwelling? The service disconnect breaker has a 200-amp rating. → 2/0 AWG
3. What is a common cause of electrical fires? → Overloaded circuits.
4. According to the NEC, Class II hazardous locations are characterized by the presence of which hazardous substance? → Combustible dust
5. Under NEC 250.50, when multiple grounding electrodes are present at a structure, what must be done? → They must all be bonded together to form a grounding electrode system
6. What color is the equipment grounding conductor insulation typically required to be? → Green or bare
7. What is the formula for calculating electrical power in a DC circuit? → P = V × I
8. Why is it important to properly size the overcurrent protection for a branch circuit? → To prevent overloading and ensure safety in case of faults.
9. In a raceway system, what must be done when the raceway is used as a sleeve through a fire-rated wall? → The raceway must be sealed with a listed fire-stop material
10. Motor feeder tap conductors that are not more than ___ length must have an ampacity that is at least ten times the feeder protection device's rating. → 10 ft
11. How do you calculate the total amperage for a branch circuit? → Dividing the total wattage by the circuit voltage.
12. In Table 310.16, what is the ampacity of 1/0 AWG copper THHN at 90°C? → 170 amps
13. What is the minimum height clearance for overhead service-drop conductors above a residential driveway? → 12 feet
14. Per NEC 210.52, receptacle outlets in a dwelling kitchen counter are required so no point along the wall line is more than what distance from a receptacle? → 24 inches
15. Which NEC chapter contains the tables for conductor properties, conduit fill, and similar reference data? → Chapter 9
16. What is the standard burial depth for a residential 120/240V branch circuit in rigid metal conduit (RMC)? → 6 in
17. The neutral conductor in a properly wired system should be bonded to ground at: → Only the service equipment/main panel
18. When a single 20-amp branch circuit supplies the bathroom receptacles in a dwelling, what else may it supply? → Only receptacles in that one bathroom
19. Using the optional method, which load is taken at the larger of 100% of A/C or 65% of central electric heating? → Heating/cooling
20. Unless specifically permitted otherwise, what is the maximum overcurrent protection allowed for a 12 AWG copper conductor according to NEC 240.4(D)? → 20A
21. For a hotel or motel with 60 guest rooms, what demand factor does NEC Table 220.42 allow on lighting loads above 120,000 VA? → 35%
22. Which of the following should not be placed over a stairway step? → overcurrent devices
23. Which NEC requirement ensures a service disconnect can be operated without reaching over energized parts? → Readily accessible location
24. Per NEC 220.12, what is the minimum general illumination load in VA per square foot for a hospital? → 2 VA/sq ft
25. What is the main purpose of the NEC's grounding requirements? → To increase the efficiency of the electrical system.
26. GFCI protection is required for 125-volt, 15- and 20-ampere receptacles installed in which dwelling location? → Garages
27. What is the demand factor allowed for the first 3,000 VA of general lighting load in a dwelling? → 100%
28. Which NEC article covers hazardous (classified) locations? → Article 500
29. What is the standard voltage used in most residential electrical systems in the U.S.? → 120 volts.
30. According to NEC Article 100, what is the definition of 'continuous load'? → A load where the maximum current is expected to continue for 3 hours or more