National Electrical Installation Standards

Standards as High as Your Own

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Tuesday, May 1, 2018

Question:

Re: CQD answer published Friday, April 20, 2018 -LFMC Support

1) There is Building codes in NY as such as 300.11 nec that offer some direction. Bill

2) Wire wraps are not "Listed" products, they normally are only "Recognized" products, which are in the UL "Yellow" books. Their use for electrical applications is limited to where they are used in a controlled situation such as a manufacturer of Industrial Control Panels. Sometimes their permitted inside panel boxes to aid in wire "marshaling" or "management" of individual conductors. They are even not "Listed" for use with communication equipment wiring such as PLTC. Use of wire wraps for any field wiring purpose per NEC would be a violation of 110.3(b) per the LFNMC manufacturer's instructions. There are no "Listed" means that I know of that facilitate attachment of LFNMC to any sort of service, including fuel gas, piping means. As a general rule, electrical raceways, equipment, enclosures, etc., are required to be mechanically supported on structural supports independent of other services or special structures such as guard rails, stairway structures. Best Regards, Nick Abbatiello

3) In Reference to Bills question LMFC supported by tie wraps to gas piping. As an inspector myself I have on many occasions found raceways supported that way and always have required it to be corrected. My corrections cite the listing of the products involved. Tie wraps are listed for support of cable assemblies and are not listed for the support of raceways. In short if you are installing a raceway assembly you must use an approved raceway support method, and cable ties/ tie-wraps are not an approved method. But see the new change to 350.30 (A) allowing this type of installation provided the cable ties are properly listed. Randy Hess

4) Regarding the support of sealtite from the generator by tie-wrapping it to the gas pipe. This along with using the same means to connect the AC sealtite to the coolant line is a common and accepted practice in our jurisdiction. Bill you must be one of those inspectors that make your own rules up as you go along. Pretty picky! George Koetters-Retired

5) In regards to wire tying carflex to a flexible natural gas line, I too would discourage this practice, although neat and workmanlike, the flexible appliance gas line may not absorb the settling or movement. If a rigiddly connected and properly support rigid gas line, I'd ok that if it serves the same connected standby generation unit ( similar to securing the protected thermostat line on a HVAC unit to the raceway used to provide power to the HVAC unit). Still your call as to suitability in your area of jurisdiction. REM

6) If I understand the question right, the installer is trying to run LFNC, FlexLine, CarFlex or some such material from the home to the generator. NFPA 70, NEC 2017 Article 356 Type LFNC 356.12 Uses Not Permitted (1) Where subject to physical damage.No matter how this was run, it would be subject to physical damage. Underground, emerging from grade may or may not be subject to repeated hits from a lawn mower or lawn tractor but here in NH it could be subject to repeated hits from a snow blower (almost every application, a path is done to a generator) and I would insist on Sch 80 PVC, intermediate or hard conduit. Then there is the manufactures FAQ sheets, this material is not allowed where there are extreme temperature swings (We had three days in February 50, 60 & 70 degrees during the day and 10 degrees at night). One manufacture will not even give a low temperature and states it becomes very brittle in cold temps. When I first saw this trying to be used some six years ago, I called the manufacture and was told it would not even stand up to a weed whacker (that and a propane line - I do not want to be that guy in the news [and the goal is safety]). At any rate, that is my take on it (Physical damage Up to the AHJ). We have had only a couple electricians try to use this. A loop above 18" for vibration purposes would seem the best use for this but here the temperature range is an issue...Thanks for this forum, miss Charlie but you do a great job with this. Thanks again, Bob

7) Hello Charlie and readers. The concept of using another trades to support electrical wiring... It seems like it would be common practice for electricians to use other trades work to support and secure wiring; framing being one of them. Masonry being another. I can see why the original question is being proposed that does not seem like a safe practice. Charlie I'm wondering if maybe this could be answered by you, are conduits allowed to be supported by other continents or piping.  I have seen another practice by solar installers where Unistrut is used and pounded into the ground and then used to support EMT or other types of conduit like rigid.. would either of these means be approved for installation by the NEC I understand that the ahj may or may not have its own opinion in this matter.. your thoughts comments and professional opinion are highly regarded! Thanks, Oliver Allen

A

Answer:

Hey all y'all thanks for the comments, lots of interesting thoughts.

1) Section 300.11 does not prohibit other items from supporting raceways.

2) Listed cable ties are available that meet the conditions in 350.30(A) and can be used for securing and supporting.

3) See answer 2).

4) Approved as defined in Article 100 is the responsibility of the AHJ as stated in 110.2.

5) See answer 4).

6) The original question was about using a gas line for support, not the suitability of the product. Neither liquidtight flexible metal conduit or liquidtight flexible nonmetallic conduit are allowed where exposed to physical damage or in temperatures they are not suitable for as stated in 350.12 and 356.12.

7) Good point, framing members, masonry, and other items installed by other trades are commonly used to support electric equipment. Raceways are generally not allowed as a means of support unless they meet the conditions in 300.11(C).

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ABOUT CHARLIE: 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. Charlie was also a member of NECA’s Academy of Electrical Contracting. Charlie’s experienced team of industry experts keep the CQD dialogue and discussions active and informative in the spirit of the man himself, as he wanted.

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