National Electrical Installation Standards

Standards as High as Your Own
 
Menu

NECA Online Help Desk
Please leave a message
Submit your Code Question | Subscribe to CQD | Un-Subscribe To CQD | Print | Share This | RSS
?
Tuesday, February 21, 2023

Question:

Hi Charlie, I have two (2) outbuildings, not attached to my residence. Building one (1) is a barn with a dedicated 320-amp meter base. I have installed two (2) 200-amp outdoor breaker panels on each side of the meter base. Panel one (1) is dedicated to the barn and is only used by the barn, and the 200-amp Panel two (2) is not being used. Building two (2) is a shop, and I am planning to run power from the barn (Building 1) to the shop (Building 2). I would like to run a single 2" conduit, underground, from the extra 200-amp panel and run two (2)-70-amp circuits to the shop, using #4 AWG copper conductors I have already have on hand. This would allow the shop to be divided into two (2) units, divided by an interior wall, both with a separate electric power panel. Would this be considered two (2) separate services to a single structure, even if they are in the same single conduit? Is installing two (2) 70-amp circuits large enough for this installation, or should I relocate the extra 200-amp panel on the barn, to the shop? Thanks in advance, Todd Topley
A

Answer:

Hello Todd, thank you for submitting such a detailed question.

To answer the first question:

This would not be considered 2 separate services. From the information provided, this would be considered two (2) feeders. The NEC® does permit multiple feeders to be installed in the same conduit if the conduit is sized large enough for all of the necessary conductors.

Section 225.30(B) permits 1-6 feeders to supply the same building under the following conditions

  1. They originate in the same panelboard/distribution equipment
  2. Each feeder terminates in a single disconnecting means
  3. All disconnecting means are grouped in the same location
  4. The disconnects are marked as to which loads they serve.
  5. To answer the second question: The size of the feeders for the shop units, will be dependent on the demand of the load to be served. Article 220 provides guidance on calculating load demand for various occupancies with various types of equipment.

ABOUT CQD: The Code Question of the Day (CQD) is NECA and ELECTRICAL CONTRACTOR Magazine’s flagship National Electrical Code (NEC®) public forum for the industry, sponsored by EATON. The daily distribution of Q&A generates a lively dialogue and shares relative Code-based practical responses.

SUBMIT YOUR CODE QUESTION: Click here to submit a question to for inclusion in an upcoming edition of the Code Question of the Day, or email codequestion@necanet.org. 

CHARLIE TROUT: Charles M. Trout, better known as Charlie, was a nationally known NEC® expert and author. He served on several NEC® technical committees and is past chairman of CMP-12. In 2006 Charlie was awarded the prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development, and technical training. Even though Charlie passed away in October of 2015, his work continues in spirit. NECA continues to maintain this question forum for its many subscribers in memory and recognition of all his significant contributions to making the NEC what it is today.

NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. NEIS can be purchased in the NECA Store in three formats: a printed or  PDF download of a standard or, as an  annual subscription service.

NECA SAFETY PRODUCTS & PUBLICATIONS: NECA produces electrical safety publications and products for the industry including jobsite safety guides, handbooks and resource kits. View a full listing of available resources and products »

IMPORTANT NOTICE: Unless the question requests a response based on a specific edition, all answers are based on the latest edition of NFPA 70® National Electrical Code®.

This correspondence is not a formal interpretation of the NEC® and any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, the NEC Correlating Committee any Code-making panel or other electrical technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services. 

UPDATE YOUR SUBSCRIPTION PREFERENCES: Subscribe or Unsubscribe from this list.

Submit your Code Question | Subscribe to CQD | Un-Subscribe To CQD | Print | Share This | RSS

© 1999 – 2014 National Electrical Installation Standards. All rights reserved.
Brought to you by NECA. NECA is the voice of the electrical contracting industry NATIONAL ELECTRICAL INSTALLATION STANDARDS, NEIS and the NEIS logo are registered trademarks of the National Electrical Contractors Association.

Created by Matrix Group International, Inc.

Follow Us on: