705.12(A) Feeder Taps.

For taps sized in accordance with 240.21(B)(2) or (B)(4), the ampacity of tap conductors shall not be less than one-third of the sum of the rating of the overcurrent device protecting the feeder plus the ratings of any power source overcurrent devices connected to the feeder.
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For taps sized in accordance with 240.21(B)(2) or (B)(4), the ampacity of tap conductors shall not be less than one-third of the sum of the rating of the overcurrent device protecting the feeder plus the ratings of any power source overcurrent devices connected to the feeder.

Code Change Summary: The language on source interconnections to feeders and feeder taps was restructured for clarity.

In the 2023 NEC®, the previous rules in 705.12(B)(1) and (2) were revised and relocated to 705.12(A).

Revised Section 705.12(A)(3) is now specific only to parallel power production source connections to feeder taps sized in accordance with 240.21(B)(2) or (B)(4). A literal interpretation of the previous 2020 language on feeder taps for interconnected power production sources could have resulted in the code requiring the tap conductors to be larger than the actual feeder they were connected to.

The revised 2023 language in 705.12(A)(3) applies when taps occur in accordance with 240.21(B)(2) or (B)(4). For these installations, the ampacity of tap conductors shall not be less than one-third of the sum of the rating of the overcurrent device protecting the feeder plus the ratings of any power source overcurrent devices connected to the feeder.

Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC® edition of NFPA 70.

2020 Code Language:

705.12(B)(1) Feeders. Where the power source output connection is made to a feeder, the feeder shall have an ampacity greater than or equal to 125% of the power-source output circuit current. Where the power-source output connection is made to a feeder at a location other than the opposite end of the feeder from the primary source overcurrent device, that portion of the feeder on the load side of the power source output connection shall be protected by one of the following:

  1. The feeder ampacity shall be not less than the sum of the primary source overcurrent device and 125% of the power-source output circuit current.
  2. An overcurrent device at the load side of the power source connection point shall be rated not greater than the ampacity of the feeder.

705.12(B)(2) Taps. Where power source output connections are made at feeders, all taps shall be sized based on the sum of 125% of all power source(s) output circuit current(s) and the rating of the overcurrent device protecting the feeder conductors for sizing tap conductors using the calculations in 240.21(B).

2023 Code Language:

705.12(A) Feeders and Feeder Taps. Where the power source output connection is made to a feeder, the following shall apply:

(1) The feeder ampacity is greater than or equal to 125% of the power-source output circuit current.

(2) Where the power-source output connection is made at a location other than the opposite end of the feeder from the primary source overcurrent device, that portion of the feeder on the load side of the power source output connection shall be protected by one of the following:

  1. The feeder ampacity shall be not less than the sum of the rating of the primary source overcurrent device and 125% of the power-source output circuit current.
  2. An overcurrent device at the load side of the power source connection point shall be rated not greater than the ampacity of the feeder.

(3) For taps sized in accordance with 240.21(B)(2) or (B)(4), the ampacity of taps conductors shall not be less than one-third of the sum of the rating of the overcurrent device protecting the feeder plus the ratings of any power source overcurrent devices connected to the feeder.

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705.12(A) Feeder Taps.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Based on the 2023 NEC, which of the following is true of 705.12(A)(3) for a tap sized in accordance with 240.21(B)(2)?

A: The feeder ampacity must be greater than 100% of the dc power-source output rating.
B: The feeder ampacity must be equal to 100% of the dc power-source output rating.
C: The ampacity of tap conductors shall not be less than one-third of the sum of the rating of the overcurrent device protecting the feeder plus the ratings of any power source overcurrent devices connected to the feeder.
D: The feeder ampacity must be greater than or equal to 100% of the dc power-source output rating.
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