Journeyman Electrician's Conductor Sizing and Ampacity Flashcards
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A 120/240V single-phase service uses 2 AWG copper conductors. What is the standard ampacity of 2 AWG copper at 75°C per NEC Table 310.15(B)(16)?
Answer: 115A
2 AWG copper conductors have a standard ampacity of 115A at 75°C per NEC Table 310.15(B)(16).
Three current-carrying conductors are bundled in a conduit. According to NEC 310.15(C)(1), what adjustment factor applies?
Answer: No adjustment needed
NEC 310.15(C)(1) requires no adjustment factor for 3 or fewer current-carrying conductors.
Which conductor material has higher conductivity, requiring a smaller gauge for equivalent ampacity?
Answer: Copper
Copper has higher conductivity than aluminum, so it carries more current at the same wire gauge.
A feeder supplies a continuous load of 80A. What is the minimum conductor ampacity required before applying breaker sizing?
Answer: 100A
Conductors for continuous loads must be sized at 125% of the load (80A × 1.25 = 100A) per NEC 215.2.
What NEC table is used to find the ampacity of conductors 0-2000V with not more than 3 current-carrying conductors in a raceway?
Answer: Table 310.15(B)(16)
NEC Table 310.15(B)(16) provides ampacity values for conductors up to 2000V with no more than 3 current-carrying conductors.
A 6 AWG aluminum conductor has what standard ampacity at 75°C per NEC Table 310.15(B)(16)?
Answer: 65A
6 AWG aluminum at 75°C has an ampacity of 65A per NEC Table 310.15(B)(16).
When using THWN-2 insulation at 75°C in a wet location, which temperature column applies for ampacity from NEC Table 310.15(B)(16)?
Answer: 75°C column
When equipment terminations are rated 75°C, the 75°C column must be used even if the insulation is rated higher.