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Conductors and Branch Circuits Flashcards

7 cards from real IEC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Conductors and Branch Circuits flashcards as text

  1. A multiwire branch circuit in a dwelling unit must have a means to simultaneously disconnect all ungrounded conductors. Which NEC section requires this?

    Answer: 210.4(B)

    NEC Section 210.4(B) requires that each multiwire branch circuit in a dwelling unit be provided with a means to simultaneously disconnect all ungrounded conductors at the panelboard.

  2. What factor primarily determines the voltage drop on a branch circuit conductor run?

    Answer: Conductor length and load current

    Voltage drop is primarily a function of conductor resistance (related to length and wire gauge) multiplied by the load current.

  3. Under NEC Article 210, which branch circuit type is required for bathroom receptacles in a dwelling unit?

    Answer: 20-ampere circuit dedicated to bathroom receptacles

    NEC Section 210.11(C)(3) requires at least one 20-ampere branch circuit dedicated to bathroom receptacles in dwelling units.

  4. When must tap conductors be protected by an overcurrent device at the point where they receive their supply?

    Answer: Exceptions in NEC 240.21 allow unprotected taps under specific length and ampacity conditions

    NEC Section 240.21 provides tap conductor exceptions that allow conductors to be run without overcurrent protection at the source under defined length and ampacity rules.

  5. Which conductor insulation temperature rating allows the highest ampacity for a given AWG size in a dry location?

    Answer: 90°C (THHN/THWN-2)

    A 90°C-rated insulation (such as THHN or THWN-2 in dry locations) permits the highest ampacity table values for a given conductor size.

  6. For a 240-volt, 2-wire branch circuit (no neutral), what conductors are present?

    Answer: Two hot conductors and one grounding conductor

    A 240V 2-wire branch circuit has two ungrounded (hot) conductors and an equipment grounding conductor; no neutral is needed since neither leg is grounded.

  7. What is the minimum headroom required above the working space for electrical panelboards supplying branch circuits in commercial occupancies?

    Answer: 6.0 feet (1.8 m) or the height of the equipment, whichever is greater

    NEC Section 110.26(A)(3) requires a minimum headroom of 6.0 feet or the height of the equipment, whichever is greater, in front of electrical equipment.