a. When more than three current-carrying conductors are installed in one raceway, their...

a. When more than three current-carrying conductors are installed in one raceway, their allowable ampacities must be reduced according to NEC_________.

b. The following is a project. We need four 15-ampere branch circuits. We will use two 3-wire multi wire branch circuits and 14 AWG THHN conductors. We will install the conductors in EMT. The room temperature will not exceed 86°F (30°C).

The connected load is non-motor and is non-continuous.

1. What is the minimum trade size EMT?_______________________________

2. What is the ampacity of the conductors before derating?

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3. What is the ampacity of the conductors after derating?

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4. What is the maximum overcurrent protection permitted for these conductors?

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c. Let’s increase the conductor size to 12 AWG THHN for the same installation to see what happens.

1. What is the minimum trade size EMT?

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2. What is the ampacity of the conductors before derating?

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3. What is the ampacity of the conductors after derating?

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4. What is the maximum overcurrent protection permitted for these conductors?

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d. It (is) (is not) necessary to count equipment grounding conductors, a neutral conductor that carries the unbalanced current from other conductors of the same circuit, and/or “travelers” when installing 3-way and 4-way switches for the purposes of derating the ampacity of these conductors. Circle the correct answer. Explain.

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