CSLB C-10 Electrical ContractorElectrical Theory and CalculationsHard
A conduit run needs to accommodate 4 AWG THHN conductors. According to NEC Table C.1 or relevant conduit fill calculations, what is the maximum number of 4 AWG THHN conductors permitted in a 1-1/2 inch EMT conduit?
- A9
- B12
- C7
- D15
Show answer & explanationAnswer & explanation
Correct answer: A. 9
To determine the maximum number of conductors, refer to NEC Chapter 9, Table C.1 for EMT conduit and THHN conductors. For 1-1/2 inch EMT, the table indicates a maximum of 9 #4 AWG THHN conductors.
Why the other options are wrong
- B. This number is incorrect for 4 AWG THHN in 1-1/2 EMT.
- C. This number is incorrect for 4 AWG THHN in 1-1/2 EMT.
- D. This number is incorrect for 4 AWG THHN in 1-1/2 EMT.
Conduit Fill (NEC Tables)
The maximum number of conductors permitted in a conduit based on conductor type, size, and conduit size, as specified in NEC Chapter 9 Tables C.1 through C.12.
- Prevents overheating and facilitates conductor installation.
- Tables are specific to conduit type (EMT, RMC, PVC) and conductor type (THHN, XHHW).
- Fill percentage limits apply if not using tables (e.g., 40% for 3+ conductors).
Memory trick: NEC Tables C: Conductor Count, Conduit Choices.