National Electrical Installation Standards

Standards as High as Your Own

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Friday, May 15, 2020

Question:

Re: Code Question of the Day for 05-11-2020

Multiple Comments on the Code Question of the Day for 05-11-2020. The comments did identify the oversight and the lack of addressing the intent of the question which was can I strip the sheath off the conductors and install them as individual conductors. Here are the comments that were submitted.                                                                                                                                                                                                                

Comment:

In reference to May 8th code question. Aside from the question on ampacity,  the stripping of nm cable (a listed assembly) and using as individual conductors would not be code compliant due to the required marking of conductors per 310.120. In other words, those conductors are not intended for use as individual conductors.

Jeffrey Reynolds

                                                                     

Comment:

Thanks for your column Thank you for your valuable service to our industry.  Regarding the question of removing the sheath from NM cable and installing it in conduit using the higher temperature rating:  the simpler answer is that you cannot remove the sheath from NM cable and use the conductors.  The required markings on the NM sheath not on the individual conductors. If you remove the sheath you have removed the required markings.

Don Haskin

                                                                                                                                                                            

Comment:

Good morning! The question asks if you can take the conductors out of NM and use them in a conduit, and the answer is no. Conductors in NM cable are not marked with the required information and cannot be used if taken out of the overall NM sheath.

Thanks, Chris Hunter

 

Comment:

You missed addressing the concept of stripping the sheath off of an NM-B cable and using the conductors as individual conductors. 

Matthew Hermanson                                                                                                                                                                                        

Comment:

Good day.  I read the CQD every day and appreciate the valuable resource in answering the wide variety of questions.  The answer to the question published May 11 for the May 8 question left out a very important part.  The question was could 6/2 NM cable be stripped, and the individual conductors installed in a piping system and use the 75C ampacity?  The conductors used to make NM cables are required to have a 90C rating by the UL standards and as stated in the response are limited to application at 60C by 334.80.  These conductors are not listed or marked conductors within the cable assembly.  The removal from the outer NM jacket to install in the conduit would now have uncertified conductors being installed.  That is why, even when sleeving in conduit, the jacketed conductor has to have the jacket intact and protruding into the box or enclosure 1/4 inch.  Thanks again for all you do, and I look forward to each day's question and answer.

Chuck Mello

 

Comment:

If I understand the question for Friday May 8th, they want to strip out 6/2 non-metallic sheathed cable. Once the outer sheathing has been removed along with all listing, nomenclature/identification, what inspector would allow unidentified wire in any piping, raceway or trough? Keep up the great work.

Bob Meade

A

Answer:

Hey folks you forgot about May 8, 2020, thanks for the question and the remarks. Section 334.80 covers the ampacity for NM cables. It indicates that the ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The allowable ampacity shall not exceed that of a 60°C (140°F) rated conductor. The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations, provided the final calculated ampacity does not exceed that of a 60°C (140°F) rated conductor. Final ampacity after ampacity adjustment or correction calculations is limited to 55 amperes. Hope this is helpful.

Thank you to all commenters on the responses for the question and answer on May 11, 2020.  Thanks for keeping us on our toes. Yes, the response did not address the main concern of the submitter. The answer is no. The jacket should not be removed from sheathed cable to use the contained conductors as individual conductors in wiring. Whenever possible, it's good to address these types of questions through consensus. We appreciate the correct comments of Jeff Reynolds, Don Haskin, Matt Hermanson, Christel Hunter, Chuck Mello, and others. Thanks for participating and bringing value to the responses.

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