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. Why is it important to properly size the overcurrent protection for a branch circuit? → To prevent overloading and ensure safety in case of faults.
6. 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
7. How do you calculate the total amperage for a branch circuit? → Dividing the total wattage by the circuit voltage.
8. In Table 310.16, what is the ampacity of 1/0 AWG copper THHN at 90°C? → 170 amps
9. What is the minimum height clearance for overhead service-drop conductors above a residential driveway? → 12 feet
10. 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
11. Which NEC chapter contains the tables for conductor properties, conduit fill, and similar reference data? → Chapter 9
12. What is the standard burial depth for a residential 120/240V branch circuit in rigid metal conduit (RMC)? → 6 in
13. The neutral conductor in a properly wired system should be bonded to ground at: → Only the service equipment/main panel
14. 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
15. Using the optional method, which load is taken at the larger of 100% of A/C or 65% of central electric heating? → Heating/cooling
16. Unless specifically permitted otherwise, what is the maximum overcurrent protection allowed for a 12 AWG copper conductor according to NEC 240.4(D)? → 20A
17. Which of the following should not be placed over a stairway step? → overcurrent devices
18. Which NEC requirement ensures a service disconnect can be operated without reaching over energized parts? → Readily accessible location
19. What is the maximum support spacing for 1/2-inch rigid metal conduit (RMC) running horizontally and secured? → 10 feet
20. The metal underground water pipe electrode must be in direct contact with earth for at least how many feet? → 10 ft
21. What is the main purpose of the NEC's grounding requirements? → To increase the efficiency of the electrical system.
22. GFCI protection is required for 125-volt, 15- and 20-ampere receptacles installed in which dwelling location? → Garages
23. What is the demand factor allowed for the first 3,000 VA of general lighting load in a dwelling? → 100%
24. Which NEC article covers hazardous (classified) locations? → Article 500
25. What is the standard voltage used in most residential electrical systems in the U.S.? → 120 volts.
26. The required working clearance in front of electrical equipment operating at 120/240 volts is generally a minimum of: → 36 inches
27. In Class I, Division 1 hazardous locations, threaded conduit connections must have at minimum how many threads fully engaged per NEC 501.10(A)(1)? → 5 threads
28. Which of the following is a correct definition from the NEC? → Grounded conductor
29. A concrete-encased electrode (Ufer ground) must use at least how much bare rebar or copper conductor? → 20 ft
30. The grounded conductor brought to a separately derived system must be bonded: → At the source or first disconnect