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Monday, April 26, 2021

Question:

Charlie,
 

I appreciate your forum. My question is if a THHN copper conductor is used for a Grounding Electrode Conductor, does it need to be installed in one of the wiring methods from Chapter 3 as addressed in Section 300.3(A) since THHN is specified in Table 310.104(A)?

Dale Earixson

A

Answer:

Hi Dale,

Thanks for the question. First, the conductor in question is a grounding electrode conductor, which does not carry current in normal operation. Article 310 would not need to be applied. Section 300.3(A) explains that single conductors specified in 310.104(A) shall only be installed where part of a recognized wiring method in Chapter 3. Again this applies to general wiring and wiring methods. Article 250 contains the specific rules related to installation of grounding electrode conductors. See Section 250.64(A) through (A) through (F). According to Section 250.62 the grounding electrode conductor can be solid, stranded, insulated covered or bare.  If a conduit is used to contain a grounding electrode conductor, it is typically for physical protection as may be required by 250.64(B). Section 250.64(B)(2) indicates the types of conduit or tubing that that shall be used for protecting sizes  6 AWG and larger, and Section 250.64(B)(3) indicates the types of conduit or tubing that shall be used for protection of sizes smaller than 6 AWG. Hope this is helpful.

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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.

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